Examples from the Ejina Basin and Orog - RWTH Publications
-
Upload
khangminh22 -
Category
Documents
-
view
1 -
download
0
Transcript of Examples from the Ejina Basin and Orog - RWTH Publications
Paleoclimatic implications from late Quaternary terrestrial
archives in the Gobi Desert: Examples from the Ejina Basin and
Orog Nuur Basin
Von der Fakultät für Georessourcen und Materialtechnik der
Rheinisch - Westfälischen Technischen Hochschule Aachen
zur Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften
genehmigte Dissertation
vorgelegt von M.Sc.
Kaifeng Yu
aus Jiangsu, China
Berichter: Univ.-Prof. Dr. rer. nat. Frank Lehmkuhl
apl. Prof. Dr. rer. nat. Bernhard Diekmann
Tag der mündlichen Prüfung: 19. August 2016
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar
Dedicated to my parents and
Cathrin, without whose support,
assistance and patience, this
endeavor would not have been
possible.
谨将此博士学位论文献给我的父
亲俞忠祥,母亲张兰英,以及凯
特琳,是他们无微不至的支持和
帮助使我能够继续追求地学梦想
并完成三年的博士工作。
Gewidmet meinen Eltern und
Cathrin, ohne deren Unterstützung,
Hilfe und Geduld diese Arbeit
nicht möglich gewesen wäre.
i
Preface
It was in 2006, during the journey to the campus of Lanzhou University, the author got the
first impression of topographic and geomorphological characteristics of the arid / semi-arid
central Asia. In 2010, after four years training in the major of physical geography, he wrote
the Bachelor thesis entitled: “Environmental changes in Sangshuyuan region of the Chinese
Loess Plateau over the last ~150 ka” supervised by Prof. Xiuming Liu, employing
paleomagnetism studies comprising anhysteretic remnant magnetization (ARM), isothermal
remnant magnetization (IRM) and coercive force (Bcr) on sediments from a ~9 m loess
sequence on the western flank of the Chines Loess Plateau (CLP). During the Master study
from 2010 to 2013, at Nanjing University, the author reviewed semi-quantified paleoclimate
signals of the Last Glacial Maximum (LGM) and Holocene Optimum (HO) in the arid
northern China under the supervision of Prof. Huayu Lu. The Master thesis is entitled: “A
preliminary quantitative paleoclimate reconstruction of the dune fields of northern China
during the Last Glacial Maximum and Holocene Optimum”.
Aforementioned field, lab, and publication experiences have prompted and enabled the author
to continue with works regarding paleoclimate changes in the arid realm. Since September
12th
, 2013, the author start with the PhD study supervised by Prof. Frank Lehmkuhl, at RWTH
Aachen, in the framework of German Federal Ministry of Education and Research project
(BMBF-CAME: 03G0814A): “Supra-regional signal pathways and long-time archives:
Quaternary monsoon dynamics at the northern margin of the Tibetan Plateau”, German
Research Foundation project (DFG: LE 730/16-1): “Late Pleistocene, Holocene and ongoing
geomorpho-dynamics in the Gobi Desert, South Mongolia” and the financial support from the
China Scholarship Council (CSC: 201306190112). The research focus is using
sedimentological and geochemical signatures incorporated in diversified sediment archives to
disentangle Quaternary paleoclimate change and sedimentary processes in the Ejina Basin and
Gobi Desert of Mongolia. To briefly outline the structure of this dissertation, the chapters are
outlined and described as follows: 1, introduction to the status of the paleoclimate research in
the research area and motivations to carry out this study; 2, geologic, climate, vegetation and
paleoglacial settings of the study area; 3, field investigations, sampling, lab and mathematic
methodologies employed in this study; 4, geochemical characteristics of different terrestrial
archives (first paper); 5, multidisciplinary study to infer the paleoenvironmental change in the
Orog Nuur catchment in the Gobi Desert (second manuscript); 6, bulk-geochemistry of the
lacustrine sediments and potential elements and ratios to decipher integrated
paleoenvironmental and provenance signals (third manuscript); 7, a synthesis concerning the
paleoenvironmental reconstruction and proxy studies; brief abstract of the dissertation in
English and in German language; references, and appendix are added at the end of this
dissertation.
俞凯峰
(Kaifeng Yu)
January 25th
, 2017
Aachen
ii
Table of contents
Page
Preface ................................................................................................................................... i
List of tables ....................................................................................................................... vii
List of figures ...................................................................................................................... ix
List of units, symbols and abbreviations ............................................................................ xv
1. Introduction .................................................................................................................. 1
1.1. Research framework and outline ................................................................................... 2
1.2. Terrestrial archives in the Gobi Desert.......................................................................... 3
1.2.1. Lacustrine sediments ............................................................................................ 3
1.2.2. Aeolian,fluvial and alluvial sediments ................................................................. 4
1.3. State of art of the paleoclimate research in the Gobi Desert and adjacent regions ....... 5
1.3.1. The Ejina Basin and arid northern China ............................................................. 5
1.3.2. The Orog Nuur catchment and Mongolian Plateau .............................................. 6
1.4. Research motivations .................................................................................................... 7
2. Regional setting .......................................................................................................... 11
2.1. Geologic and geomorphic setting ................................................................................ 11
2.1.1. The Ejina Basin .................................................................................................. 11
2.1.2. The Orog Nuur catchment .................................................................................. 13
2.2. Climate regime ............................................................................................................ 14
2.2.1. Climate of the Ejina Basin ................................................................................. 14
2.2.2. Climate of the Orog Nuur catchment ................................................................. 15
2.3. Soils and vegetation cover ........................................................................................... 16
2.4. Paleo- and modern glacial setting ............................................................................... 17
2.5. Anthropo-zoogenic setting .......................................................................................... 17
3. Materials and methods ............................................................................................... 19
3.1. Field work and sampling strategy ............................................................................... 19
3.2. Laboratory methods ..................................................................................................... 20
3.2.1. Chronological methods ....................................................................................... 20
3.2.2. Grain size analysis .............................................................................................. 21
3.2.3. X-ray fluorescence analysis and X-ray diffraction ............................................. 22
3.2.4. Electrical conductivity and magnetic susceptibility measurements ................... 23
3.2.5. Carbon, nitrogen, sulfur, TOC and CaCO3 analyses .......................................... 23
3.2.6. Pollen, non-pollen palynomorphs and palynofacies analyses ............................ 23
3.2.7. Ostracod analysis ................................................................................................ 24
3.3.Mathematical methods: Correlations and multivariate statistics .................................. 24
4. Discriminating sediment archives and sedimentary processes in the arid
endorheic Ejina Basin, NW China using a robust geochemical approach ........... 26
iii
4.1. Introduction ................................................................................................................. 27
4.2. Regional Setting .......................................................................................................... 30
4.3. Methods ....................................................................................................................... 31
4.3.1. Sampling strategy ............................................................................................... 31
4.3.2. Chronological methods ....................................................................................... 32
4.3.3. Grain size analysis .............................................................................................. 33
4.3.4. X-ray fluorescence analysis and X-ray diffraction ............................................. 36
4.3.5. Correlations and multivariate statistics .............................................................. 37
4.4. Results ......................................................................................................................... 38
4.4.1. Lithology and chronology .................................................................................. 38
4.4.2. Granulometric composition and pre-assessment of archives ............................. 40
4.4.3. Elemental and mineralogical composition of archives ....................................... 43
4.4.4. Element assemblages and loadings as derived from conventional and robust
factor analysis ............................................................................................................... 45
4.5. Discussion ................................................................................................................... 47
4.5.1. Late Quaternary lithostratigraphy at the northern margin of the Ejina Basin .... 47
4.5.2. Elemental characteristics of sediment archives .................................................. 48
4.5.2.1. Elemental characteristics compared to granulometric composition .... 48
4.5.2.2. Elemental characteristics of sediment archives ................................... 49
4.5.3. Geochemical interpretation of sedimentary processes ....................................... 51
4.6. Conclusions ................................................................................................................. 53
5. Lake sediments documented late Quaternary humid pulses in the Gobi Desert of
Mongolia: Vegetation, hydrologic and geomorphic implications .......................... 55
5.1. Introduction ................................................................................................................. 56
5.2. Study Area ................................................................................................................... 59
5.2.1. Geologic and geomorphic setting ....................................................................... 59
5.2.2. Climatic and vegetation setting .......................................................................... 60
5.2.3. Paleo- and modern glacial setting ...................................................................... 62
5.3. Material and methods .................................................................................................. 62
5.3.1. Cores retrieval and sampling strategy ................................................................ 62
5.3.2. Lithology and chronology .................................................................................. 63
5.3.3. Grain size analysis .............................................................................................. 64
5.3.4. Electrical conductivity and magnetic susceptibility measurements ................... 65
5.3.5. Carbon, nitrogen, sulfur, TOC and CaCO3 analyses .......................................... 66
5.3.6. X-ray fluorescence analysis, color analysis and multivariate statistics ............. 66
5.3.7. Palynology .......................................................................................................... 67
5.3.8. Ostracod analysis ................................................................................................ 68
5.4. Results ......................................................................................................................... 68
5.4.1. Bayesian chronology and lithostratigraphic units .............................................. 68
5.4.2. Bulk-geochemistry of the lacustrine sediments ................................................. 71
5.4.3. Palynological results .......................................................................................... 71
5.4.3.1. Unit 1 (LPZ 1; 1,335-1,235 cm; ~50-~43 cal ka BP) .......................... 72
5.4.3.2. Unit 2 (LPZ 2; 1,235-1,120 cm; ~43-~37 cal ka BP) .......................... 73
iv
5.4.3.3. Unit 3 (LPZ 3; 1,120-1,057 cm; ~37-~35 cal ka BP) .......................... 73
5.4.3.4. Unit 4 (LPZ 4; 1,057-660 cm; ~35-~24 cal ka BP) ............................. 73
5.4.3.5. Unit 5 (LPZ 5; 660-390 cm; ~24-~19 cal ka BP) ................................ 73
5.4.3.6. Unit 6 (LPZ 6; 390-350 cm; ~19-~18 cal ka BP) ................................ 74
5.4.3.7. Unit 7 (LPZ 7; 350-248 cm; ~18-~13 cal ka BP) ................................ 74
5.4.3.8. Unit 8 (LPZ 8; 248-205 cm; ~13-~11 cal ka BP) ................................ 74
5.4.3.9. Unit 9 (LPZ 9; 205-25 cm; ~11-? cal ka BP) ...................................... 74
5.4.4. Ostracod species and valve abundances ............................................................. 75
5.5. Discussion ................................................................................................................... 76
5.5.1. Vegetation dynamics and hydrologic history of the Orog Nuur ........................ 76
5.5.1.1. Unit 1 (~50-~43 cal ka BP): relatively humid Artemisia steppe around
a shallow lake ................................................................................................... 77
5.5.1.2. Unit 2 (~43-~37 cal ka BP): relatively dry and fluctuating Artemisia
steppe and water surplus to the lake ................................................................. 78
5.5.1.3. Unit 3 (~37-~35 cal ka BP): relatively dry Artemisia steppe and lake
stabilization ....................................................................................................... 79
5.5.1.4. Unit 4 (~35-~24 cal ka BP): relatively humid Artemisia steppe and
transition from maximum high to quite low lake levels ................................... 81
5.5.1.5. Unit 5 (~24-~19 cal ka BP): Artemisia steppe and playa to shallow lake
.......................................................................................................................... 81
5.5.1.6. Unit 6 (~19-~18 cal ka BP): Artemisia steppe and sand accumulation 82
5.5.1.7. Unit 7 (~18-~13 cal ka BP): Artemisia steppe, higher lake level and
decreasing river influence ................................................................................. 82
5.5.1.8. Unit 8 (~13-~11 cal ka BP): Establishment of deserts around a strongly
shrinking lake .................................................................................................... 83
5.5.1.9. Unit 9 (~11-? cal ka BP): desert steppe and a shallow lake of high
salinity and alkalinity ........................................................................................ 83
5.5.2. Geomorphic evidence of the past environmental change in the Orog Nuur
catchment ..................................................................................................................... 86
5.5.2.1. Glacial advances in the higher reaches of the Orog Nuur catchment .. 86
5.5.2.2. Ancient shorelines of the Orog Nuur ................................................... 88
5.5.3. Regional synthesis - humid pulses inferred from different archives in the
vicinity of the Gobi Desert ........................................................................................... 88
5.5.3.1. Marine Isotope Stage 3 ........................................................................ 89
5.5.3.2. Marine Isotope Stage 2 ........................................................................ 90
5.5.3.3. The Holocene ....................................................................................... 90
5.5.4. Potential driving mechanisms for the late glacial climate change in the Gobi
Desert ........................................................................................................................... 91
5.5.4.1. Humid pulses in the Gobi Desert ......................................................... 92
5.5.4.2. Playa phases in the Gobi Desert .......................................................... 93
5.6. Conclusions ................................................................................................................. 94
6. Geochemical imprints of coupled paleoenvironmental and provenance change in
the lacustrine sequence of Orog Nuur, Gobi Desert of Mongolia .......................... 97
6.1. Introduction ................................................................................................................. 98
v
6.2. Regional setting ......................................................................................................... 101
6.3. Material and methods ................................................................................................ 101
6.3.1. Core retrieval and Bayesian age-depth modelling ........................................... 101
6.3.2. Grain size analysis ............................................................................................ 103
6.3.3. TOC, CaCO3 and C/Natomic analyses ................................................................ 104
6.3.4. X-ray fluorescence scanning and X-ray powder diffraction analysis .............. 105
6.3.5. Robust multivariate statistics ........................................................................... 105
6.4. Results ....................................................................................................................... 106
6.4.1. Lithostratigraphic units and Bayesian chronology ........................................... 106
6.4.2. Elements/minerals downcore variance and multi-proxy assemblages revealed by
multivariate statistics .................................................................................................. 108
6.5. Discussion ................................................................................................................. 110
6.5.1. Evaluating the quality of the X-ray scanning data ........................................... 110
6.5.2. Governing factors for sediment bulk-geochemistry ......................................... 111
6.5.2.1. Factor 1 (26.4%): Grain-size variation of the lacustrine sediments .. 111
6.5.2.2. Factor 2 (15.5%): Authigenic productivity of the saline/alkaline
lacustrine environment .................................................................................... 112
6.5.2.3. Factor 3 (8.4%): Organic material content ........................................ 113
6.5.2.4. Factor 4 (25.9%): Terrigenous components via riverine input and
quasi-constant aeolian input ........................................................................... 113
6.5.3. Biplots of elements and scores plot as indicators of a distinct provenance signal
and high authigenic productivity of the lake system in the Holocene ....................... 117
6.5.3.1. The disparate provenance signatures and authigenic productivity of the
Holocene sediments ........................................................................................ 118
6.5.4. Summary of coupled paleoenvironmental, weathering, catchment land surface
processes, and provenance signals over the past ~50 ka BP in the Orog Nuur
catchment ................................................................................................................... 121
6.5.4.1. Unit I (~50-~19 cal ka BP): shallow to lentic water body, moderate
catchment weathering ..................................................................................... 121
6.5.4.2. Unit II (~19-~18 cal ka BP): playa phase and minor riverine inflow 121
6.5.4.3. Unit III (~18-~13 cal ka BP): shallow saline lake, moderate weathering
in higher catchment ......................................................................................... 122
6.5.4.4. Unit IV (~13-~11 cal ka BP): playa phase with slightly more riverine
inflows relative to LGM ................................................................................. 122
6.5.4.5. Unit V (<~11 cal ka BP): lentic hypersaline lake with abruptly
increased terrigenous inputs and authigenic productivity .............................. 123
6.6. Conclusions ............................................................................................................... 124
7. Synthesis: Paleoclimatic implications from late Quaternary terrestrial archives in
the Gobi Desert ......................................................................................................... 127
7.1. Bulk-geochemistry of different terrestrial archives in the arid realm and their
corresponding implications for the paleoenvironmental, pedogenesis and diagenesis
processes ..................................................................................................................... 127
7.2. Sedimentological, palynological and ostracod studies of the lacustrine sediments and
references to the paleohydrological and vegetation history ....................................... 128
vi
7.3. Geochemical imprints of the lacustrine sediments and integrated paleoenvironmental
and provenance implications ..................................................................................... 129
7.4. Outlook ...................................................................................................................... 130
References ........................................................................................................................ 132
Appendix .......................................................................................................................... 159
R script employed in the dissertation ............................................................................... 160
Acknowledgements .......................................................................................................... 163
Abstract ........................................................................................................................... 167
Zusammenfassung .......................................................................................................... 169
vii
List of Tables
Tab. 2-1: Inventory of the plutonic rocks, volcanic/subvolcanic rocks and Quaternary deposits
in the Orog Nuur catchments. For geologic mapping refer to Fig. 1-3. This set of sources
rocks is of vital importance concerning the bulk-geochemistry discussed in Chapter 6 ......... 16
Tab. 4-1: Results of the AMS 14
C-dating. Radiocarbon ages were calibrated to calendar years
with 2 σ standard deviation using the CALIB rev.7.1 (Stuiver et al., 1998) with the latest
calibration dataset (Intcal13.14c, Reimer et al., 2013) ............................................................. 38
Tab. 4-2: Summary of water content, equivalent dose value (De), dose rate, number of used
aliquots and luminescence ages of samples from study sections. 238
U, 232
Th and 40
K
concentrations were determined by Neutron Activation Analysis (NAA). Absolute uncertainty
of the water content was assumed to be < ±5%. Due to saturation of the equivalent dose, brief
constrained luminescence ages are presented here. More details concerning the method see
Chapter 4.3.2 ............................................................................................................................ 39
Tab. 4-3: Results of the oxides of ten major elements expressed as normalized wt % and other
trace elements concentrations (ppm) of sediment archives as determined by X-ray
fluorescence analysis. Decimal precision of the reported concentrations were revised
according to the formats of their counterparts in the UCC data set (Rudnick and Gao, 2003).
Root mean square errors (RMS) and lower limit of detection (LOD) of each element see
Spectro Xepos (2007) ............................................................................................................... 43
Tab. 4-4: Standard deviations, variance / cumulative proportions, element loadings for each
factor, and communalities for each element. High positive or negative (>0.75) loadings are
shown in boldface, proportions in %. ....................................................................................... 46
Tab. 5-1: The AMS 14
C ages were calibrated to calendar years with 2 σ standard deviation
using the CALIB rev. 7.1 (Stuiver et al., 1998) with the latest IntCal13.14c (Reimer et al.,
2013). According to the estimated real age based on the lithostratigraphy, raw radiocarbon
ages are subtracted by a reservoir effect of ~3,400±2,100 a BP before computing to calibrated
ages and generating the Bayesian age-depth model as given in Fig. 5-4 ................................. 63
Tab. 5-2: Synthesis of lacustrine, pelagic, aeolian and glacial sequences (spanning at least the
MIS 3) in the vicinity of the Gobi Desert ................................................................................. 85
Tab. 6-1: The AMS 14
C ages were calibrated to calendar years with 2 σ standard deviation
using the CALIB rev. 7.1 (Stuiver et al., 1998) with the latest IntCal13.14c (Reimer et al.,
2013). According to the estimated real age based on the lithostratigraphy, raw radiocarbon
ages are subtracted by a reservoir effect of ~3,400±2,100 a BP before computing to calibrated
ages and generating the Bayesian age-depth model as given in Fig. 6-2 ............................... 103
Tab. 6-2: Standard deviation, variance/cumulative proportion, multi-proxies loading for each
factor, and communalities for each proxy generated by robust multivariate statistics. High
positive or negative (> 0.75) loadings are marked in boldface. Blank values represent those
loadings which are under significance level in robust multivariate statistics. Communalities
for each element are computed by taking sum of the seared loadings, it can be referred to the
length of the element arrows in loadings plot (Fig. 6-4A), a value greater than 0.90 suggests a
well representative of this proxy in the statistical model. Factors 1 (26.4%) and 4 (25.9%)
explain more than have of the variance, they are therefore illustrated in the biplots of Fig. 6-4
for further implications. More details concerning the statistics refer to Yu et al. (2016) ...... 106
viii
Tab. 6-S1: Synoptic description of the coupled paleoenvironmental and provenance signatures
during the past ~50 ka BP as inferred from the lacustrine sequence of Orog Nuur. A schematic
model comprising these factors is proposed in Fig. 6-6 in the main text ............................... 125
Tab. A1: Ratios from major elements to oxides and corresponding functions ...................... 159
ix
List of Figures
Fig. 1-1: Atmospheric circulations over the central and eastern Asia, with panel A denoting
the summer pattern and panel B representing winter pattern. Solid lines indicate ca. 3,000 m
a.s.l. airflow while dashed lines indicate earth surface flow at ca. 600 m (adapted from Benn
and Owen, 1998; Lehmkuhl and Haselein, 2000; Barry and Chorley, 2009; An et al., 2014;
Loibl, 2015). Study areas of Ejina Basin and Orog Nuur Basin are marked as white rectangle
in the panels. More detailed analyzed sections in this dissertation refer to following Figs. 2-2
and 2-3. ....................................................................................................................................... 2
Fig. 2-1: Photographs of representative contexts in the study area: (A) Gobi surface and
Precambrian intrusive bedrocks with background of Mountains in Mongolia. (B) Megadunes
on the northern margin of Badain Jaran Desert. (C) Common observed Haloxylon
ammodendron on the gobi surface. (D) Unparallelled sand ripples on the dune surface. (E)
Playa surface of western Juyanze Basin with particularly high contend of evaporite minerals.
(F) The ancient city Khara Khoto (synonyms: Black City, abandoned in 1,372 A.D.) and
nearby accumulated dunes. ...................................................................................................... 12
Fig. 2-2: Geologic map and section locations in the northern Ejina Basin: Section HC8 is an
escarpment between the western and eastern Juyanze sub-basin. Sections KK1 and KK2 are
located by the braided river channel near ancient of Khara Khoto. Sections WT1 and WT2 are
yardangs located on the margin of Wentugaole Sub-basin and Badain Jaran Desert. Black
(dash-) lines denote strike-slip neotectonics compiled from Wünnemann et al. (2007), Hölz et
al. (2007), Hartmann et al. (2011), Cunningham (2013) and Rudersdorf et al. (2015). D100
correspond to the drilling core from Wünnemann (1999) and Wünnemann et al. (2007) ....... 13
Fig. 2-3: Present-day distribution of geologic terranes in the Orog Nuur catchment (marked
with dashed line). Northern region of Orog Nuur Basin is dominated with Devonian-Triassic
felsic quartz syenite, granite and plagiogranite, accompanied by intermediate mafic fractions.
Southern region of Orog Nuur exhibit increasing fraction of mafic and ultramafic basalt and
andesite-basalt rocks. Alkaline syenite occurs sporadically in the lower Orog Nuur
catchments. The depositional basin is bounded by eastern Khangai in the north and the Gobi
Altai Mountains in the south. More details concerning representative minerals see Tab. 2-1.
Concerning the geomorphological and topographic settings refer to Fig. 5-2 of the same
region ........................................................................................................................................ 15
Fig. 2-4: Schematic north-south oriented topographic transect and corresponding vegetation
patterns. The eastern parts of Khangai Mountains (higher reach of the Orog Nuur catchment)
with altitudes between 3,500 m and 3,700 m a.s.l. have no modern glaciers, while small ice-
fields may reach down to 3,200 m a.s.l. in the western Khangai Mountains (Lehmkuhl and
Lang, 2001) .............................................................................................................................. 18
Fig. 4-1: Simplified geologic map and section locations in the northern Ejina Basin: (A)
Section HC8 is an escarpment between the western and eastern Juyanze sub-basin. Sections
KK1 and KK2 are located by the braided river channel near ancient of Khara Khoto. Sections
WT1 and WT2 are yardangs located on the margin of Wentugaole Sub-basin and Badain
Jaran Desert. Black (dash-) lines denote strike-slip neotectonics compiled from Wünnemann
et al. (2007), Hölz et al. (2007), Hartmann et al. (2011), Cunningham (2013) and Rudersdorf
et al. (2015). Black bold lines denote schematic elevation cross-section in panel B. D100
correspond to the drilling core from Wünnemann, 1999 and Wünnemann et al., 2007. (B)
Cross-section from Khara Khoto to Juyanze (playa) and Wentugaole (sub-basin) ................. 29
x
Fig. 4-2: Photographs of representative geomorphological contexts from the northern Ejina
Basin: (A) Inverted channels near Khara Khoto. (B) Gobi surface and Precambrian intrusive
bedrocks in Wentugaole sub-basin. (C) Khara Khoto and nearby accumulated dunes. (D)
Yardangs in southern Wentugaole sub-basin. (E) Playa surface of western Juyanze Basin. (F)
Megadunes on the northern margin of Badain Jaran Desert .................................................... 31
Fig. 4-3: Lithostratigraphy and generally constrained chronology framework. Chronology
framework is labeled, and 2-sigma ranges for calculated radiocarbon ages are reported in Tab.
4-1. U1 is the lowermost aeolian sands (except for WT1), U2 is lacustrine stratum, and U3 is
fluvial sands (mixed with gravels) unit (e.g., Fig. 4-2A). U3 of HC8 is especially thick
mixture of poorly-sorted coarse alluvial sands and gravels ..................................................... 32
Fig. 4-4: Example of wave-length dispersive spectrums of X-ray diffraction (XRD). Panels A
to E denote aeolian sands, lacustrine clay, fluvial sands, sandy loess, alluvial gravels,
respectively from section HC8 (with depth). The powdered samples were scanned from 3° to
40° at °2θ, angle spectrums are conducted by Xpert Highscore software, the classification of
impulses following Hartmann & Wünnemann (2009). The number of counts is illustrated as
reference for e.g., aeolian sands ............................................................................................... 35
Fig. 4-5: Conceptual modal of the robust geochemical approach to discriminate archives and
sequence sedimentary processes .............................................................................................. 36
Fig. 4-6: Ternary diagrams of granulometric properties and A-CN-K (molar proportions): (A)
Granulometric ternary diagram. (B) A-CN-K ternary diagram, CaO is corrected to silicate
carbonate following the procedure of McLennan (1993). The Chemical Index of Alteration
(CIA, Nesbitt & Young, 1982) is related on the right side of the A-CN-K triangle.
Abbreviations: A=Al2O3, C=CaO, N=Na2O, K=K2O, Ka=Kaolinite, Gi=Gibbsite,
Ch=Chlorite, Il=illite, Mu=muscovite, Pl=plagioclase, Bi=Biotite, Ks=alkali feldspar,
Ch=chlorite, Cp=clinopyroxene, Hb=hornblende .................................................................... 40
Fig. 4-7: Granulometric properties of archives: (A) aeolian sands (n=51), (B) lacustrine clay
(n=19), (C) fluvial sands (n=18), (D) sandy loess (n=2), (E) alluvial gravels (n=2), different
axis scales are used ................................................................................................................... 41
Fig. 4-8: Spearman’s rank correlation coefficients between geochemical properties and grain
size parameters (all scales of red to blue units have passed 0.05 significant level). Not all
elements exhibit grain-size dependence (e.g., As, Nd, S and Al). Red pixels denote positively
correlated and blue ones depict negative correlations. These features can also shed light on
elemental characteristics of archives. C, fSi, mSi, cSi, fS, mS and cS denote the particle size
of clay, fine silt, medium silt, coarse silt, fine sand, medium sand and coarse sand,
respectively ............................................................................................................................... 42
Fig. 4-9: Loading and score plot of geochemical data set: (A) Loading plot of conventional
factor analysis, with thirty elements. (B) Score plot of conventional factor analysis, with thirty
elements. (C) Loading plot of robust factor analysis, with sixteen elements. (D) Score plot of
the robust factor analysis, with sixteen elements. Originally, the maximum direction of
variance will be regarded as axes, however, rotation is performed to get varimax rotated axis
(i.e., X-and Y-axis here) during the factor analysis to provide a higher loading for each
elements (Tab. 4-4). Cosine of the angle between the elements arrow and the component
(varimax rotated axes) are factor loadings, length of the arrows are corresponding to the
element communalities. Compared with conventional factor analysis (Panels A and B), panels
C and D exhibit higher cumulative proportions for RFs 1 and 2. Dashed line circles in panels
xi
A and C denote communality estimates (Tab. 4-4) and thereby assess the quality for each
element (> 0.9 can be regarded as good quality) in this factor modal. Panels B and D illustrate
that multivariate statistic of elemental fingerprints appears to be a practical method to
discriminate the archive types, of which mistakes may be yielded from field investigations
and GSD observations alone .................................................................................................... 44
Fig. 4-10: Principle component scores, main mineral compositions and granulometric
properties of section HC8, RF1: weathering intensity, RF2: silicate-bearing mineral
abundance (different within lacustrine and aeolian phase), RF3: saline magnitude of
sediments, and RF4: quasi-constantly aeolian input. Lithologic patterns refer to Fig. 4-3. Clay
mineral group includes smectite, illite, kaolinite and chlorite. C, fSi, mSi, cSi, fS, mS and cS
denote the particle size of clay, fine silt, medium silt, coarse silt, fine sand, medium sand and
coarse sand, respectively .......................................................................................................... 51
Fig. 5-1: Location of the study area and paleoclimate records mentioned in the text (1, Kanas
Basin; 2, Darhad Basin; 3, Hovsgol Nuur; 4, Shaamar section; 5, Baikal Lake; 6, Kotokel
Lake; 7, Wulagai Lake; 8, Manas Lake; 9, Luanhaizi Lake; 10, Wuliangsu Lake; 11, Japan
Sea; 12, Lake Biwa; 13, Khangai Glacier; 14, Altai Glacier. More details refer to Tab. 4-3).
Panel A delineates schematic vegetation cover of Mongolia. Large-scale air mass controls are
marked with arrows, comprising East Asian Summer Monsoon (EASM), Indian Summer
Monsoon (ISM) and Westerlies. Ulaan Nuur (Lee et al., 2011, 2013) and Bayan Tohomin
Nuur (Felauer et al, 2012) are the only two reported lacustrine archives in the central to
southern Mongolia. Panel B exhibits north-south oriented topographic transect and
corresponding vegetation patterns. The eastern parts of Khangai Mountains (higher reach of
the Orog Nuur catchment) with altitudes between 3,500 m and 3,700 m a.s.l. have no modern
glaciers, while small ice-fields may reach down to 3,200 m a.s.l. in the western Khangai
Mountains (Lehmkuhl and Lang, 2001) ................................................................................... 57
Fig. 5-2: Geomorphological map of the Orog Nuur Basin, three sets of lake beaches were
synthesized based on previous investigations. Section A1 is located at the third (highest) set of
sand ridge, more details see Chapter 5.5.2.2. General content is adapted after J. Grunert and F.
Lehmkuhl, and original cartography by T. Bartsch ................................................................. 59
Fig. 5-3: Schematic lithologic column, photographs of sliced drilling core ONW II along with
the reference logs. Abbreviations: cl, clay; fsi, fine silt; msi, medium silt; csi, coarse silt; fs,
fine sand; ms, medium sand, cs, coarse sand. Mudstone or siltstone is represented in
schematic colors according to core description. In general, greyish calcareous clays (upper
fraction), siltstone and intercalated sandstones constitute the entire lacustrine sequence ....... 61
Fig. 5-4: Polylinear regression age-depth model of core ONW II generated from the
radiocarbon ages. Reservoir effect is corrected by (i) late Pleistocene/Holocene transition
(Termination I) as inferred from the suite of granulometric, palynological, ostracod and
geochemical studies (marked as black triangle), and (ii) the Younger Dryas related sand layer
(Ulaan Nuur, Lee et al., 2013). Frequency-dependent magnetic susceptibility (χFD), electrical
conductivity (EC), CaCO3, TOC and C/Natomic ratios of parallel core ONW I are employed to
cross-validate the age model of core ONW II. More details with respect to the
lithostratigraphy and chronological framework see text in Chapter 5.4.1 ............................... 64
Fig. 5-5: Lithologic units of the core ONW II, and corresponding granulometric, geochemical,
and color variances. The grey bars depict the primary sand layers inferred from the
granulometric and lithostratigraphic characteristics of the core .............................................. 65
xii
Fig. 5-6: Diagram of analyzed taxa of pollen, fungal spores, aquatic algae and non-pollen
palynomorphs through the core ONW II plotted against the age and depth. All taxa were
aggregated into groups consist of arboreal plants (trees), shrubs, subshrubs/herbs/grasses,
aquatics, as well as coprophilous fungi and Glomus ................................................................ 67
Fig. 5-7: Scanning electron micrographs of ostracod valves derived from core ONW II
(external views). 1, juvenile Candona neglecta left valve (LV); 2-3, Leucocythere
dorsotuberosa, 2, female right valve (RV), 3, male LV; 4-11, Limnocythere inopinata, 4,
female LV, 5, female RV, 6, noded female LV, 7, noded female RV, 8, male LV, 9, male RV,
10, juvenile LV with spines along posteroventral margin, 11, juvenile RV with spines along
posteroventral margin; 12, juvenile Pseudocandona sp. LV; 13, Ilyocypris cf. inermis RV, 14,
Ilyocypris manasensis var. cornae LV, 15, Ilyocypris cf. bradyi LV ...................................... 69
Fig. 5-8: Absolute abundances of determined ostracod species, number of taxa and number of
valves plotted against lithologic units ...................................................................................... 72
Fig. 5-9: Semi-quantified thermal, moisture and hydrogeochemical history as inferred from
the palynological and geochemical studies. Palynological indices (curves a and b) are inferred
from pollen concentration and Artemisia/Chenopodiaceae ratios, respectively, whilst the
geochemical indices (curves c and d) i.e., factor scores, are entrained from multivariate
statistics based on the bulk-geochemistry of the sediments (Yu et al., 2016). Fossil pollen
concentration is linked to the thermal anomalies (e.g., Conroy et al., 2009). Considering the
authigenic productivity, the Holocene may experience a distinct lacustrine phase with higher
content of calcite and carbonates. In this study, the vertical blue bars depict humid pulses,
while yellow bars denote the playa phase inferred from the granulometric and
lithostratigraphic characteristics of the core. Furthermore, as stated in Chapter 5.4.3, the
pollen assemblages preserved in the lacustrine archive may indicate merely local vegetation
signals surrounding the lower catchment of the Orog Nuur. Therefore, inconsistency between
the reconstructed effective moisture and lake level fluctuations may occur. Northern
hemisphere temperature (e): Johnsen et al. (2001), H events: Bond et al. (1993), 45 °N
summer insolation (f): Whitlock and Bartlein (1997), west subtropical pacific SST (g) and sea
level changes (h): Tudhope et al. (2001). In addition, the MIS 3/MIS 2 transition in this study
is some 24 cal ka BP, which is largely in agreement with that in Martinson et al. (1987) ...... 78
Fig. 5-10: Synthesis and comparison of paleoenvironmental variability in Mongolia and
adjacent regions since the Marine Isotope Stage 3 as developed in this study and other
selected records from literatures: 1, Kanas Glacial (Xu et al., 2009; Zhao et al., 2013); 2,
Manas Lake (Rhodes et al., 1996); 3, Darhad Glacial (Gillespie et al., 2008); 4, Hovsgol Nuur
(Murakami et al., 2010); 5, Luanhaizi Lake core LH2 (Mischke et al., 2005b); 6, Baikal Lake
(Williams et al., 1997; Prokopenko et al., 2001); 7, Kotokel Lake (Shichi et al., 2009); 8,
Retreat of southern boundary of the Gobi Desert (Feng et al., 2007); 9, Shaamar Section (Ma
et al., 2013); 10, Wuliangsu Lake (Selvaraj et al., 2012); 11, Wulagai Lake (Yu et al., 2014);
12, Biwa Lake (Xiao et al., 1997); 13, Japan Sea (Nagashima et al., 2007); 14, Dust model in
central Asian desert (Nilson and Lehmkuhl, 2001). Here, the vertical blue bars depict humid
pulses, while yellow bars denote the playa phase inferred from the granulometric and
lithostratigraphic characteristics of the core. Calibrated radiocarbon ages were labeled as
black triangles near the bottom axis. Climate intervals including the Younger Dryas (YD) and
Last Glacial Maximum (LGM) were demarcated near the uppermost axis. More details
concerning the proxies of each archive refer to Tab. 5-2 and locations refer to Fig. 5-1A ..... 80
Fig. 5-11: Synoptic compilation of hydrologic, vegetation and geomorphic history of the Orog
Nuur catchment over the last ~50 ka. Playa & dune phase is recovered from the granulometric
xiii
and lithostratigraphic characteristics of the core ONW II. More details see Chapter 5.5.1.
Glacial advance in Khangai Mountains refer to Rother et al. (2014) and Lehmkuhl et al.
(2016). As mentioned in Chapter 5.5.3.3, in the Holocene, the high termpertature induced
higher evapouration might have triggered lower annual moisture in the catchment (see A/C
ratios in Fig. 5-9), it has however less impacts on the better hydrological condition of the
water body as revealed by higher authigenic productivity (Fig. 5-9) in the more alkaline water
column (see Chapter 6.5.2.2, and Fig. 6-6). ............................................................................. 92
Fig. 5-S1: Diagram of analyzed taxa of pollen, fungal spores, aquatic algae and non-pollen
palynomorphs through the core ONW II plotted against the age and depth. All taxa were
aggregated into groups consist of panel (A) arboreal plants, humidity indicators, aquatic algae,
and panel (B) aridity indicators and grazing indicators ........................................................... 96
Fig. 6-1: Present-day distribution of geologic terranes in the Orog Nuur catchment. Northern
region of Orog Nuur Basin is dominated with Devonian-Triassic felsic quartz syenite, granite
and plagiogranite, accompanied by intermediate mafic fractions. Southern region of Orog
Nuur exhibit increasing fraction of mafic and ultramafic basalt and andesite-basalt rocks.
Alkaline syenite occurs sporadically in the lower Orog Nuur catchments. The depositional
basin is bounded by eastern Khangai in the north and the Gobi Altai Mountains in the south
.................................................................................................................................................. 99
Fig. 6-2: Lithostratigraphy and Bayesian age-depth modelling for core ONW II. R package
Bchron (Parnell et al., 2008) was employed. Gray shaded area represents maximum and
minimum age-depth estimates based on 100,000 smooth spline fits through the calibrated age
distributions (95% highest density region). The Bayesian age-depth model was further cross-
validated by several independent approaches: (i) two ages from the parallel core ONW I
(marked as black rectangles), (ii) sand layer and luminescence-determined age model of
Ulaan Nuur (Lee et al., 2011), (iii) downcore variance of CaCO3 concentration .................. 102
Fig. 6-3: Downcore variance of abundance of the major and trace elements expressed by
integrated peak areas (total counts per second), accompanied by the C/Natomic ratios, CaCO3
content, Rb/Sr ratio (lower values= higher catchment weathering; Davies et al., 2015), Al/Si
ratio (lower values=higher coarse-grained sands; Davies et al., 2015), and the XRD
determined minerals in sparser intervals. Silicon and K share similar patterns as Al, whilst Mn
and Co share similar patterns as Fe. Further details are presented in the supplementary
material of this paper. The grey bars depict the sand layers inferred from the granulometric
and lithostratigraphic characteristics of the core, and the dashed line mark the transition of
Termination I. The consistency between the grey bars and the elements spikes implies that the
sand fractions (Factor 1 as determined by robust statistics; Fig. 6-4) have played a pivotal role
in the alteration of bulk-geochemistry of the lacustrine sediments. ....................................... 104
Fig. 6-4: Loadings and scores plot of the multi-proxy data set. Panel A: loading plot of the
robust Factor 1 (grain-size) vs. 4 (terrigenous input). Panel B: score plot of the robust Factor 1
vs. 4. In multivariate statistics, the maximum direction of variance is regarded as axes.
Rotation is performed to get varimax rotated axis (x- and y-axis in Panel A) during the
analysis attempting to archive a higher loading for each elements (Tab. 6-2). Cosine of the
angle between the proxies and varimax rotated axes are factor loadings, length of the arrows
are corresponding to the proxy communalities. In panel B, all units of samples are defined
based on their lithostratigraphic units .................................................................................... 109
Fig. 6-5: Bivariate plots of major and trace elements in peaks areas (y-axis) against Al/Si (x-
axis) according to their stratigraphic units. Al/Si ratios indicate generally the grain-size
xiv
compositions of the bulk sediments, which display lower values/spikes according to the
coarse-grained sand layers (Fig. 6-3). The biplot of Ca vs. Al/Si seems like a useful tool to
properly discriminate the instinct (i) source rocks changes, and (ii) authigenic productivity in
comparison with the late Pleistocene units. This distinct Holocene samples characteristics are
more clearly elaborated in the scores plot of Fig. 6-4B ......................................................... 115
Fig. 6-6: Schematic model of the integrated past environmental change, land surface
processes and provenance signals (carbonate geochemistry) of the Orog Nuur catchment over
the last ~50 ka. The eastern parts of Khangai Mountains (higher reach of the Orog Nuur
catchment) with altitudes between 3,500 m and 3,700 m asl. have no modern glaciers. More
details regarding glacial and vegetation developments in the catchment are given in Lehmkuhl
and Lang (2001), Rother et al. (2014), and Lehmkuhl et al. (2016). Distinct geochemical
signals for each phase also refer to the table in supplementary material of this paper .......... 120
Fig. 6-S1: Dispersion plots of the major and trace element concentrations (peak areas)
according to their stratigraphic units. Numbers of observations for each unit are marked on the
upmost axis. The median values are linked with dash lines, while the upper and lower
quartiles are marked as error bars .......................................................................................... 126
Fig. 7-1: Synoptic compilation of hydrologic, vegetation and glacial history of the Orog Nuur
catchment over the last ~50 ka. Playa & dune phase is recovered from the granulometric and
lithostratigraphic characteristics of the core ONW II. Likewise, this late Glacial high lake
levels are also recorded in the Ejina Basin as lacustrine facies.............................................. 127
xv
List of Units, Symbols and Abbreviations
Units of the International System (SI) have been guidelines in this dissertation. Unless
otherwise specified, the abundances of trace element are based on the total content by weight
of those in oven-dried material.
Units:
A.D. anno Domini, used to label or number years in Julian and Gregorian calendars
a.s.l. above sea level
cal ka BP calculated thousand years before present (1950 A.D.)
ppm parts per million; 1 ppm = 1 µg/g
Symbols:
AMS Accelerator mass spectrometry
ELA Equilibrium Line Altitude
pH Minus logarithm, base 10, of H+ concentration
Abbreviations:
AMOC Atlantic Meridional Overturning Circulation
CNS Analysis of total carbon, nitrogen and sulfur
ECORD European Consortium for Ocean research Drilling
EGU European Geosciences Union
ESR Electron spin resonance
gLGM global Late Glacial Maximum
GSD Grain size distribution
INQUA International Union for Quaternary Research
IODP Integrated Ocean Drilling Program
ITCZ Intertropical Convergence Zone
MIS Marine Isotope Stage
OSL Optically stimulated luminescence
REE Rare earth element
XRD X-ray Diffraction
XRF X-ray fluorescence
YD Younger Dryas
1
“Arid regions are areas of concern, because of
population growth, the impacts of desertification and of
natural phenomena, particularly droughts” (David S.G.
Thomas, 1996)
1. Introduction
Being a fragile ecological system, environmental change in arid central Asia exerts
tremendous influence on a significant percentage of population concerning nomadic migration
and alternation of political regimes (Pederson et al., 2014). The arid central Asia (Fig. 1-1) is
sensitive to paleoclimate changes. The comprehensive framework of alluvial fans, terraces,
periglacial mass movement, aeolian and lacustrine sediments has documented the manner of
the paleoclimate changes as well as the markedly anthropological influences since the late
Holocene (Lehmkuhl and Haselein, 2000). Lehmkuhl et al. (2003) reported a successive
geomorphological section in the arid central Asia from higher Khangai Mountain to the Gobi
Desert, Badain Jaran Desert, Qilian Mountain, Qaidam Basin and eventually to the NE Tibet
(Fig. 1-1). According to climatic and topographic settings, this section covers a holistic array
of geomorphic units including glacial and periglacial landforms, pediments/bajadas, steppe
and desert gorges, aeolian landforms and floodplain valleys with meandering rivers. In
conjunction with high resolution sampling, well constrained chronological framework and
robust interpretations of physical, geochemical and geobiological proxies, all this set of
archives has the potential to serve as pivotal repository for paleoclimate (thermal and
moisture) signals, which in turn will benefit the climate modelling and archaeological studies.
The Gobi Desert in arid northern China and southern Mongolia was recognized as one of the
main dust sources for Chinese Loess Plateau and pelagic sediments in the western Pacific
(Pye and Zhou, 1989; Xiao et al., 1997; Lu and Sun, 2000; Vandenberghe et al., 2006).
Previously, broad pattern of late Quaternary (in particular Holocene) paleoclimate signatures
of arid central Asia were defined and reviewed by Pachur and Wünneman (1995), Yang et al.
(2004, 2011), Feng et al. (2005), Herzschuh (2006), Chen et al. (2008), An et al. (2008),
Wang et al. (2010) and Wang and Feng (2013). Ample compilations have suggested a distinct
moisture regime of middle and southern Mongolia in comparison to that of higher latitude
Baikal catchments and East Asian Summer Monsoon (EASM) domain of northern and eastern
China (Yang et al., 2004; An et al., 2008; Wang et al., 2010; Wang and Feng, 2013).
However, it remains elusive with respect to how and to what extent have EASM and
2
Westerlies affected the thermal and moisture signals in this spectacularly arid region. In
addition, substantially temporal and spatial heterogeneity exist in this arid realm, namely,
most of the records have poured attention into temporally the Holocene period and spatially,
the arid northern China and northwestern Mongolia.
Fig. 1-1: Atmospheric circulations over the central and eastern Asia, with panel A denoting
the summer pattern and panel B representing winter pattern. Solid lines indicate ca. 3,000 m
a.s.l. airflow while dashed lines indicate earth surface flow at ca. 600 m (adapted from Benn
and Owen, 1998; Lehmkuhl and Haselein, 2000; Barry and Chorley, 2009; An et al., 2014;
Loibl, 2015). Study areas of the Ejina Basin and Orog Nuur Basin are marked as white
rectangle in the panels. More detailed analyzed sections in this dissertation refer to following
Figs. 2-2 and 2-3.
In this dissertation, terrestrial archives including aeolian, fluvial/alluvial and lacustrine
sediments are selected and retrieved from the Ejina Basin and Orog Nuur (nuur = lake)
catchment, respectively (Fig. 1-1), in trying to decipher the late Quaternary
paleoenvironmental signals based on a robust multidisciplinary study. In addition, this
dissertation is assembled primarily from three manuscripts (i.e., Chapters 4, 5 and 6). Several
fractions in Chapter 1 may therefore overlap with paragraphs in those chapters.
1.1. Research framework and outline
This dissertation work is carried out in the framework of (i) German Federal Ministry of
Education and Research project (BMBF-CAME: 03G0814A): “Supra-regional signal
pathways and long-time archives: Quaternary monsoon dynamics at the northern margin of
the Tibetan Plateau”, (ii) German Research Foundation project (DFG: LE 730/16-1): “Late
Pleistocene, Holocene and ongoing geomorpho-dynamics in the Gobi Desert, South
3
Mongolia” and (iii) the financial support from the China Scholarship Council (CSC:
201306190112). The focus of this dissertation is using sedimentological and geochemical
signatures incorporated in diversified terrestrial archives to decipher late Quaternary
paleoclimate change and sedimentary processes in the Ejina Basin and Gobi Desert of
Mongolia. On the other hand, additional studies including geobiological proxy analysis (i.e.,
palynology and ostracod) and geomorphological investigations were also conducted
(Lehmkuhl and Lang, 2001; Hempelmann, 2010; Felauer, 2011; Hülle, 2011; Murad, 2011)
with the intention to gain a sound and compelling paleoenvironmental implications. To briefly
outline the structure of this dissertation, the main chapters are outlined as follows: 1,
introduction to the status of the paleoclimate research in the research area and motivations to
carry out this study; 2, geologic, geomorphological, climate, vegetation, paleoglacial and
anthropo-zoogenic settings of the study area; 3, field investigations, sampling, lab and
mathematic methodologies employed in the study; 4, geochemical characteristics of different
terrestrial archives (the Ejina Basin; first manuscript); 5, multidisciplinary study to infer the
paleoenvironmental change in the Orog Nuur catchment in the Gobi Desert (the Orog Nuur
catchment; second manuscript); 6, bulk-geochemistry of the lacustrine sediments and
potential elements and ratios to decipher integrated paleoenvironmental and provenance
signals (the Orog Nuur core; third manuscript); 7, a synthesis concerning the
paleoenvironmental reconstruction and proxy studies; brief abstract of the dissertation in
English and German language; references, and appendix are added at the end of this
dissertation.
1.2. Terrestrial archives in the Gobi Desert
To address those issues rose at the very beginning of the chapter, careful selection and full
understanding of the geological repository is a prerequisite and pivotal step.
1.2.1. Lacustrine sediments
In the context of the Gobi Desert, lacustrine sequence is a critical archive for climate and
provenance signatures. In particular in the arid central Asia, due to scarcity of abundant
continuous loess-paleosol or oceanic archives, lacustrine records were more often employed
as the Quaternary paleoenvironmental repository (Boyle, 2001; Mischke et al., 2005; Jin et
al., 2015). Southern Mongolia is located on the margin of the Westerlies dominated arid
central Asia and East Asian Summer Monsoon dominated costal eastern Asia (Chen et al.,
2008). Acquiring of a continuous and chronological reliable past environment record in this
4
region is of exceedingly importance concerning the refinement of the understanding of the
comprehensive climate pattern and possible corresponding driving mechanisms. However,
there exist hitherto numerous spatial and temporal heterogeneities concerning the archives. In
the Gobi Desert of Mongolia, only two continuous records were previously reported i.e.,
Bayan Tohomin Nuur (Felauer et al., 2012) and Ulaan Nuur (Lee et al., 2011; 2013).
Nonetheless, none of these two cores provide paleoenvironment records that trace back to
ages before ~15 ka. A record spanning longer time period is therefore indispensable to
address aforementioned issues.
1.2.2. Aeolian, fluvial and alluvial sediments
Apart from the lacustrine sequence, it is also indispensable to gain a better understanding
concerning other terrestrial archives embracing aeolian, fluvial and alluvial sediments to
figure out the robust paleoenvironmental implications. Previously, the main factors
controlling geochemical compositions of sediments are the nature of parent rocks, chemical
weathering, diagenesis, mechanical disaggregation and abrasion, authigenic / allothigenic
input, and metamorphism in case of relatively old e.g., early Cenozoic and Mesozoic
sediments (Bhatia, 1983; Johnsson, 1993; Fralick and Kronberg, 1997; Young et al., 1998;
McLennan, 2001; S. Yang et al., 2004; Xu et al., 2011). Analyzing geochemical
characteristics along with other characteristics of sediments is therefore a powerful tool to
decipher the nature of aforementioned processes. Previously, elemental (isotopic) and mineral
fingerprints have been employed to evaluate the provenance of the American loess /
mudstones / sandstones (Gallet et al., 1998; Zhang et al., 2014b), European loess (Amorosi et
al., 2002; Buggle et al., 2008; Újvári et al., 2014), Eastern / Central Asian loess / desert sands
(Liu et al., 1993; Honda and Shimizu, 1998; Jahn et al., 2001; Honda et al., 2004; Yang et al.,
2007; Maher et al., 2009; Stevens et al., 2010; Chen and Li, 2011; Xu et al., 2011; Xiao et al.,
2012; Wang et al., 2012) and Greenland dust (Újvári et al., 2015). Nesbitt and Young (1982)
reported the major element content to represent a quantitative chemical weathering proxy,
whereas in absence of strong chemical weathering (e.g., in arid and semi-arid environments,
Zhu et al., 2014), the bulk-composition and mineralogy can be explained by physical
abrasion, comminution and sorting (Nesbitt and Young, 1996; von Eynatten et al., 2012).
Elemental characteristics of lacustrine or aeolian deposits have been employed to reconstruct
the paleoenvironmental change in the northern Tibetan Plateau and the Mongolian Plateau
during the late Quaternary (e.g., Hartmann and Wünnemann, 2009; Schwanghart et al., 2009;
Lu et al., 2010; IJmker et al., 2012a; Felauer et al., 2012; Guo et al., 2013). Apart from
5
provenance and paleoenvironmental studies, the nature of bulk-compositions of different
sediment archives is hitherto incompletely understood. On the other hand, whether and how
geochemical composition can be assigned to sedimentary processes in arid region is seldom
studied. To further decipher the past processes and controlling factors, a better understanding
of the geochemical fingerprints recorded in these archives is needed.
1.3. State of art of the paleoclimate research in the Gobi Desert and adjacent regions
1.3.1. The Ejina Basin and arid northern China
In the arid northern China, i.e., where Ejina Basin locates, from west to east, either deserts or
dunefields embracing Badain Jaran Desert, Tengger Desert, Mu Us Desert, Horqin, Songnen
and Hunlunbuir Sandfield have dominated the region (Lu et al., 2013; Yu et al., 2013). In this
arid realm, as compiled from peat bog, loess-paleosol sequences, lacustrine sediments, a
sensitive alteration of the documented moisture and thermal signals in response to the
paleoclimate changes are concluded (Yu et al., 2013). In particular, compared with modern
times, the temperature has decreased by 5-11 °C and the precipitation decreased by 180-350
mm during the Last Glacial Maximum (LGM, ~26-~16 ka in global scale), whilst the
temperature has increased by 1-3 °C and the precipitation increased by 30-400 mm in the
Mid-Holocene Optimum (~9-~5 ka in global scale) (Yu et al., 2013). In the arid and semi-arid
regions of northern China, particularly, in basin systems, lacustrine / playa, aeolian and
alluvial / fluvial sediments are common. Spatial and temporal characteristics of these
sediments are correlated to littoral and pelagic deposition systems of paleolake expansion and
desiccation (Wünnemann, 1999), which can be ascribed to climatic variations. The endorheic
Ejina Basin is regarded as a fundamental dust provenance of the Chinese Loess Plateau and
adjacent regions (Pye and Zhou, 1989; Lu and Sun, 2000; Vandenberghe et al., 2006; Sun et
al., 2008). For the Ejina Basin and adjacent areas, the land relief, geomorphological
backgrounds, late Pleistocene deposition characteristics, neotectonic constrains and
hydrological changes were conducted by Wünnemann et al. (1999, 2007), Mischke et al.
(2003), Hartmann et al. (2009, 2011), Wang et al. (2011) and Zhu et al. (2014). Deciphering
the geochemical characteristics of archives in this basin system would have been one crucial
step towards a better understanding of the paleoenvironmental changes and sedimentary
processes that are related to dust activities (see Chapter 4).
6
1.3.2. The Orog Nuur catchment and Mongolian Plateau
Further to the north, more attentions have been dedicated to the northern and western
Mongolia as well as the Baikal catchments in Russia, albeit most of the lacustrine sequence
listed here spans no longer than the Holocene period: Baikal Lake (Horiuchi et al., 2000;
Karabanov et al., 2000; Prokopenko et al., 2001; Murakami et al., 2012; Kostrova et al.,
2014), Kotokel Lake (Shichi et al., 2009), Karakul Lake (Komatsu et al., 2015), Hovsgol
Nuur (Tarasov et al., 1999; Fedotov et al., 2004; Karabanov et al., 2004; Prokopenko et al.,
2002, 2007; Hovsgol Drilling Project Members, 2009; Murakami et al., 2010; Fumiko
Watanabe et al., 2014), Khuvsgul Nuur (Orkhonselange et al., 2013); Bayan Nuur (Dorofeyuk
and Tarasov, 1998; Nauman, 1999), Telmen Nuur (Peck et al., 2002; Fowell et al., 2003),
Khuisiin Nuur (Tian et al., 2013; 2014), Gun Nuur (Feng et al., 2005; Zhai, 2008; Zhang et
al., 2012), Ugii Nuur (Schwanghart et al., 2008, 2009; Wang et al., 2009), Uvs Nuur (Walther,
1999; Grunert et al., 2000), Hoton Nuur (Tarasov et al., 2000; Rudaya et al., 2009), Lake
Tuolekule (An et al., 2011); Tsetseg Nuur (Klinge and Lehmkuhl, 2013); Dada Nuur (Gunin,
1999), Yamant Nuur (Gunin, 1999), Dood Nuur (Dorofeyuk and Tarasov, 1998), Achit Nuur
(Gunin, 1999), Ulaan Nuur (Lee et al., 2011; 2013) and Bayan Tohomin Nuur (Felauer et al.,
2012). In addition, concerning other terrestrial archives, several loess paleosol sequences e.g.
Karakorum (Lehmkuhl et al., 2011), Shaamar (Feng et al., 2005) and Khyaranny (Feng et al.,
2001) were reported. The well dated interstadial Marine Isotope Stage 3 (MIS 3) paleoglacial
advance in Altai Mountain, Kanas River valley, Western Khangai, and Darhad Basin were
previously published by Reuther et al. (2006), Gillespie et al. (2008), Xu et al. (2009),
Lehmkuhl et al. (2011; 2015), Zhao et al. (2013), and Rother et al. (2014), providing
promising marks of the paleoclimate signals in this arid/semi-arid region. In general, the high
pedogenesis i.e., soil layers and large scale glacial expansions are intimately correlated to the
higher moisture supplies. However, especially in the central to southern Mongolia, all this
suite of studies has presented an urgent requirement to retrieve and reverse a reliable
paleoclimate sequence spanning longer time periods than the Holocene.
As aforementioned, on the Mongolian Plateau and adjacent arid central Asia, continuous
lacustrine sequences are widely regarded as fundamental repository for paleoenvironmental
signatures. A wealth of works has been reported concerning the late Quaternary moisture and
thermal history. However, an array of paramount aspects still needs to be tackled. They are
summarized as follows: (i) biased or even contradictory conclusions may occur due to the
interpretations of different proxies. For instance, Schwanghart et al. (2009) advocated a
7
warmer and wetter mid-Holocene in Ugii Nuur (in central-northern Mongolia) as inferred
from the mineral composition and bulk-geochemistry, while an arid mid-Holocene was
reconstructed from palynology studies (Wang and Feng, 2013). (ii) Most of the works poured
attention into the Holocene period, while only few records addressed the climate history
during the Pleistocene (Pachur and Wünnemann, 1995; Feng et al., 1998; Grunert et al., 2000;
Lehmkuhl and Haselein, 2000). (iii) Substantial spatial heterogeneity is also noteworthy.
Amount of studies on lacustrine deposits were carried out in the Baikal catchments in Russia,
northern and western Mongolia and northern China. Only two lacustrine sequences were
hitherto conducted in southern Mongolia, namely, Bayan Tohomin Nuur (Felauer et al., 2012)
and Ulaan Nuur (Lee et al., 2013) (cf., Fig. 5-1A). Furthermore, above problems might have
been reinforced by uncertainties in different radiocarbon age models due to a varying hard
water effect (Mischke et al., 2013).
On the other hand, among the suite of the multidisciplinary studies on argillaceous sediments,
geochemistry appears most likely the promising tool to decipher the interplay between the
environmental change, source lithotype and sediment bulk-composition (Boyle, 2001).
Considering the late Quaternary lacustrine sediments, the bulk-geochemistry may be
controlled by source terranes, authigenic or allothigenic input, which may be modulated by
the past environmental conditions, while pedogenesis and diagenesis might exert only limited
overprints (Yu et al., 2016). Knowledge of the major and minor element abundance downcore
variance along with the field investigation and carefully examined geologic mapping will
thereby enable us to gain a better understanding of the climate-induced environment and
provenance changes throughout the deposition process. Furthermore, surveys considering the
major and minor element abundance and corresponding environmental interpretations in the
pelagic realm have been systematically conducted and reviewed (Calvert and Pedersen, 2007),
while their counterpart elucidations in the lacustrine sediments still await more investigations
(cf., Roser and Korsch, 1988; Norman and De Deckker, 1990; Roy et al., 2012; Doberschütz
et al., 2013; Davies et al., 2015; Liang and Jiang, 2015).
1.4. Research Motivations
As reviewed above, an array of paramount aspects has inhibited our complete understanding
of the broad pattern of Quaternary moisture and thermal history of the arid central Asia and
their underlying mechanisms. Main knowledge gaps are summarized as follows:
8
(1) It remains elusive regarding how and to what extent have EASM and Westerlies affected
the thermal and moisture signals in this spectacularly arid region;
(2) Most of the geologic records have poured attention into the Holocene period, whereas
only few records can extend back to earlier marine isotope stages;
(3) Substantially spatial heterogeneity is noteworthy in the area. Exceeding amounts of
studies were carried out in the Lake Baikal catchment, northern and western Mongolia,
while only two continuous lacustrine sequences (spanning ~ 15 ka) were hitherto
conducted in southern Mongolia (Lehmkuhl and Lang, 2001; Felauer et al., 2012; Lee et
al., 2013);
(4) Concerning identical archive sequences, biased or even contradictory conclusions may
occur due to the interpretations of palynological and bulk-geochemical signals (e.g.,
Schwanghart et al., 2009; Wang and Feng, 2013), multidisciplinary study is therefore
indispensable to reconstruct sound paleoenvironmental signals;
(5) Apart from provenance and paleoenvironmental studies, the nature of bulk-compositions
of different sediment archives and different granulometric proportions is hitherto
incompletely understood. On the other hand, whether and how geochemical composition
can be assigned to sedimentary processes in arid region is seldom studied. To further
decipher the past processes and controlling factors, a better understanding of the
geochemical fingerprints incorporated in this set of terrestrial archives is needed;
(6) Surveys considering the bulk-geochemistry and corresponding environmental
interpretations in the marine realm have been systematically conducted and reviewed,
while their counterpart explanations in the lacustrine sediments still await more
investigations (cf., Boyle, 2001; Calvert and Pedersen, 2007).
Based on those knowledge gaps, the core fraction of the dissertation is outlined and
demarcated into three chapters, from which Chapter 4 is dedicated to the Ejina Basin while
Chapters 5 and 6 represent the multidisciplinary study on two lacstrine drilling cores ONW I
and ONW II recovered in the Orog Nuur catchment:
Manuscript 1: Discriminating sediment archives and sedimentary processes in the arid
endorheic Ejina Basin, NW China using a robust geochemical approach (Chapter 4):
In this study, a geochemical approach in conjunction with a broad field of granulometric,
mineralogical and generally constrained chronological data is presented in order to:
Identify the broad pattern of lithologic units at the northern margin of the Ejina Basin;
9
Differentiate the distinct nature of bulk-compositions in different granulometric
compositions and the array of archives obtained from these units;
Employ a multivariate statistic approach to test which assemblages of elements are
suitable, sensitive and robust to reconstruct sedimentary processes and thereby to evaluate
the controlling factors for the bulk-composition of sediments in (semi-)arid regions.
Hence, ultimately, the aim is to improve our understanding of the intriguing sedimentary
processes in this arid terrestrial endorheic context.
Manuscript 2: Lake sediments documented late Quaternary humid pulses in the Gobi Desert
of Mongolia: Vegetation, hydrologic and geomorphic implications (Chapter 5):
A multidisciplinary study is performed on a critically selected lacustrine sequence in
attempting to gain a robust and unambiguous knowledge of the past environmental changes.
In this study, two carefully selected parallel cores were recovered from Orog Nuur, in
southern Mongolia. Based on previous investigations, a multidisciplinary study involving
sedimentology, bulk-geochemistry, palynology, and ostracod analyses were carried out on
lacustrine cores ONW I and ONW II, intending to:
Gain a reliable knowledge of moisture history in the Orog Nuur catchment over the last
~50 ka, and its governing atmospheric circulation pattern;
Elucidate broad pattern of interrelated vegetation and hydrologic history of the Orog Nuur
catchment;
Generate and refine understandings on the spatial and temporal traits of moisture and
thermal signals in Gobi Desert of Mongolia, with aid of comparison with adjacent aeolian,
pelagic and mountainous glacial expansion records.
Manuscript 3: Geochemical imprints of coupled paleoenvironmental and provenance change
in the lacustrine sequence of Orog Nuur, Gobi Desert of Mongolia (Chapter 6):
In this study, high resolution major and trace element contents accompanied by calcium
carbonate concentration and C/Natomic ratios of the lacustrine sequence are examined in
attempts to:
Test the possible element ratios that can be employed to extract the broad pattern of the
diversified source terranes throughout the depositional period;
In terms of certain elements e.g., Co, Mn and Zr, examine the underlying driven
mechanism and environmental interpretation in the lacustrine realm;
10
In conjunction with briefly constrained mineral abundance, an array of major and trace
elements’ downcore variance were illustrated to indicate the interplay in the integrated
paleoenvironmental and provenance change in the depositional system.
11
“Mongolia is situated where contrasting geological
structures intersect, within the zone of interaction of
different systems of global atmospheric circulation.
Here, at the junction of the Siberian taiga forest,
Dahurian steppes, and Gobi desert is a crossroad of
plant and animal distribution” (P.D. Gunin et al, 1999)
2. Regional setting
The Gobi Desert covers a broad area including both northern China as well as the central to
southern Mongolia (Fig. 2-1). In this dissertation, two representative study areas comprising
the Ejina Basin in the south and the Orog Nuur catchment in the north are selected.
2.1. Geologic and geomorphic setting
2.1.1. The Ejina Basin
The Ejina Basin (synonym: Gaxun Nur Basin) lies in the lower reaches of the endorheic Hei
River catchment (with an area of ca. 130,000 km2, Fig. 2-2), which contains one of the
world’s largest continental alluvial fan systems (Hartmann et al., 2011). The basin covers an
area of about 28,000 km2
and is fed by the Hei River discharging from the Qilian Mountains.
The elevation ranges from 880 to 1,300 m above sea level (a.s.l.) (Hartmann et al., 2011) and
late Quaternary sediments are up to ~300 m thick (Zhang et al., 2006; Hartmann and
Wünnemann, 2009). The infilling of the basin started probably at earliest 250 ka ago, as
retrieved from the D100 drilling core (Fig. 2-2, 42.1°N 100.85°E, 940 m a.s.l., Wünnemann,
1999, Wünnemann et al., 2007a). Paleozoic to Mesozoic intrusive bedrock can be observed in
the northern Juyanze and Wentugaole basins (Fig. 2-2, Becken et al., 2007; Rudersdorf et al.,
2015). The basin is bound by the Heli Mountains in the south, the Bei Mountains to the west,
the Badain Jaran Desert / Alashan Plateau to the east and the Gobi Altai Mountains to the
north (Fig. 2-2). Temporal and spatial patterns of fluvial and lacustrine deposition are
influenced by neotectonics (e.g., the western margin has a subsidence rate of ca. 0.8-1.1 m/ka,
cf., Hartmann et al., 2011). Nowadays, only the Ejina oasis near Juyanze paleolake receives
ephemeral water input (Hartmann et al., 2011). Typical geomorphological features are gravel
plains, yardangs, playas, sand fields and sporadically distributed mobile linear and barchan
dunes (Zhu et al., 2014; Fig. 2-1).
12
Fig. 2-1: Photographs of representative contexts in the study area: (A) Gobi surface and
Precambrian intrusive bedrocks with background of Mountains in Mongolia. (B) Megadunes
on the northern margin of Badain Jaran Desert. (C) Common observed Haloxylon
ammodendron on the gobi surface. (D) Unparallelled sand ripples on the dune surface. (E)
Playa surface of western Juyanze Basin with particularly high contend of evaporite minerals.
(F) The ancient city Khara Khoto (synonyms: Black City, abandoned in 1,372 A.D.) and
nearby accumulated dunes.
13
Fig. 2-2: Geologic map and section locations in the northern Ejina Basin: Section HC8 is an
escarpment between the western and eastern Juyanze sub-basin. Sections KK1 and KK2 are
located by the braided river channel near ancient of Khara Khoto. Sections WT1 and WT2
are yardangs located on the margin of Wentugaole Sub-basin and Badain Jaran Desert.
Black (dash-) lines denote strike-slip neotectonics compiled from Wünnemann et al. (2007),
Hölz et al. (2007), Hartmann et al. (2011), Cunningham (2013) and Rudersdorf et al. (2015).
D100 correspond to the drilling core from Wünnemann (1999) and Wünnemann et al. (2007).
2.1.2. The Orog Nuur catchment
The Orog Nuur catchment lies in the Valley of Gobi Lakes in southern Mongolia (Fig. 2-3;
Tab. 2-1). The Orog Nuur is a brackish habitat that is subjected to desiccation and it
occasionally turns into a playa environment. Tuyn Gol (gol = river) is the main inflow that
originates from the southern slopes of Khangai Mountains around 220 km north of the lake.
The lake has no conspicuous outflow, resulting in a hydrologically closed basin system. The
northwest-southeast orientated Valley of Gobi Lakes (ca. 1,400 to 1,800 m above sea level,
a.s.l.) is an elongated intramontane depression between the Siberian Craton and the Tarim and
Sino-Korean Cratons (Baljinnyam et al., 1993; Windley and Allen, 1993; Cunningham et al.,
1996, 1997; Owen et al., 1999; Bardarch et al., 2000; Webb and Johnson, 2006; Cunningham,
14
2013; Guy et al., 2014). The Valley of Gobi Lakes is bounded by the Khangai Mountains in
the north and Gobi Altai Mountains in the south (Fig. 2-3B). The maximum elevation of the
Khangai Mountains is around 4,000 m a.s.l. at Otgon Tenger Uul in the west (4,008 m a.s.l.,
47°36’30”N, 97°33’09”E) and ca. 3,000 m a.s.l. at Erhet Hayrhan Uul in the east (3,037 m
a.s.l., 46°39’18”N, 101°13’56”E), whilst the Gobi Altai has a summit at 3,957 m a.s.l. (Ikh
Bogd Uul: 44°59’42”N, 100°13’51”E; uul = mountain). A left lateral strike-slip fault is
located at the southern side of the Khangai Mountains (Tapponnier et al., 1979; Walker et al.,
2007; Cunningham, 2013), while the southern part of the Orog Nuur watershed exhibits the
tectonic escarpment of the Gobi Altai and gently inclined alluvial fans (Baljinnyam et al.,
1993; Johnson, 2004; Vassallo et al., 2007, 2011). The elongated forebergs of the Gobi Altai
are markedly faulted, warped and partially uplifted by thrust faults (Owen et al., 1997;
Bayasgalan et al., 1999). For instance, in the Gobi Altai, due to the 1957 earthquake with a
magnitude of 8.3, left-lateral displacements reached 6 m and vertical displacements
approached 1.5 m (Baljinnyam et al., 1993), which may lead to misinterpretations regarding
the shoreline ridges or terraces. Paleozoic volcanic and plutonic rocks are exposed in the basin
and some places are overlain by conglomerates. Previously, a much larger lake extent in the
basin was reconstructed based on three sets of shorelines (Lehmkuhl and Lang, 2001;
Komatsu et al., 2001; Grunert et al., 2009). This suite of recessional beaches are determined
to be ~60 m, ~23 m and ~16 m, respectively, higher than the modern lake-level. East-west
oriented mobile dunes and cuspate bars lie in the vicinity of the Orog Nuur (Stolz et al.,
2012).
2.2. Climate regime
2.2.1. Climate of the Ejina Basin
The Ejina basin as part of the Gobi Desert is located beyond the limits of the East Asian
Summer Monsoon (cf., Chen et al., 2008). The winter Siberian Anticyclone dominates the
climate regime (Chen et al., 2008; Mölg et al., 2013). The mean January and July air
temperatures are ca. -11°C and 26 °C, respectively. More than 90% of the ca. 38 mm annual
precipitation occur between July and early September, albeit the annual precipitation in the
upper reaches of the Hei River catchment in the Qilian Mountains can reach 300-500 mm
(Wang and Cheng, 1999; Wünnemann et al., 2007a). The theoretical potential evaporation is
around 3,700 mm.
15
Fig. 2-3: Present-day distribution of geologic terranes in the Orog Nuur catchment (marked
with dashed line). Northern region of Orog Nuur Basin is dominated with Devonian-Triassic
felsic quartz syenite, granite and plagiogranite, accompanied by intermediate mafic fractions.
Southern region of Orog Nuur exhibit increasing fraction of mafic and ultramafic basalt and
andesite-basalt rocks. Alkaline syenite occurs sporadically in the lower Orog Nuur
catchments. The depositional basin is bounded by eastern Khangai in the north and the Gobi
Altai Mountains in the south. More details concerning representative minerals see Tab. 2-1.
Concerning the geomorphological and topographic settings refer to Fig. 5-2 of the same
region.
2.2.2. Climate of the Orog Nuur catchment
Further to the north, Mongolia is dominated by a continental climate characterized by dry and
cold winter and a precipitation maximum in summer (An et al., 2008). The mean annual
precipitation along a north-south transect ranges from ~500 mm to <100 mm. 65-75 % of the
precipitation occurs in summer due to the enhanced south-eastern cyclonic activity along the
polar front (Kostrova et al., 2014). Only ~100 mm precipitation is delivered in the lower Gobi
Desert of southern Mongolia, while the higher elevated Khangai Mountains can reach ~400
mm. According to records at Bayankhongor weather station near the Orog Nuur, the mean
16
July and January temperature in the Gobi Desert are ~16 °C and ~-20 °C, respectively, while
the mean annual temperature is about -2 °C to 5 °C (Felauer, 2012). In spring, dust- or
sandstorms frequently occur with maximum wind speeds exceeding 20 m/s (Hempelmann,
2010; Felauer, 2012). There is generally no snow cover because of the immense winter
dryness related to the predominant Siberian Anticyclone (Kostrova et al., 2014).
Tab. 2-1: Inventory of the plutonic rocks, volcanic / subvolcanic rocks and Quaternary
deposits in the Orog Nuur catchments. For geologic mapping refer to Fig. 1-3. This set of
sources rocks is of vital importance concerning the bulk-geochemistry discussed in Chapter 6.
Plutonic rocks and complexes Volcanic and subvolcanic rocks Genetic types of
Quaternary deposits
Ultramafic Mafic a alluvial
σ dunite, peridotite, serpentinite melange β basalt l lake
Mafic μβ diabase, dolerite al alluvial-lake
συ ultrabasite-basitic layered series τβ trachybasalty g glacier
η anorthosite Intermediate d talus
ση gabbro-troctolite-anorthositic complex αβ andesitebasalt p proluvial
υ gabbro, gabbronorite ταβ trachyandesite basalt dp proluvial-talus
υδ gabbrodiorite α andesite v aeolian
Intermediate τα trachyandesite
δ diorite Felsic
qδ quartz diorite λ dacite, rhyolite, quartz porphyry
Felsic μλ rhyodacite, trachrhyodacite
δ-γ diorite-granitic complex τλ trachydacite, trachyrhyolite
γδ granodiorite, tonalite, plagiogranite Bimodal
γ granite, leucogranite βλ spilite-keratophyric and
γξ granosyenite, quartz syenite, subalkaline granite basalt-rhyolitic complexes
γ-γξ granite-granosyenitic
γπ granite-porphyry
Alkaline
ευ alkaline gabbro, ijolite, urtite
εξ nepheline syenite, alkaline syenite
εγ alkaline granite
2.3. Soils and vegetation cover
Primary soil type in central to southern Mongolia is dry-steppe Kastanozems. Other common
soil types are Chernozems/dark Kastanozem in the forest-steppe zone as well as brown
semidesert soils (Tamura et al., 2012). In modern context, arable soil is relatively scarce in
both the Ejina Basin and Orog Nuur catchment. The modern vegetation follows a north-south
transect from alpine tundra, mountain taiga, mountain/forest steppe, grass steppe, desert
steppe (Orog Nuur catchment) and finally to desert communities such as the Ejina Basin (Fig.
1-1; Hilbig, 1995; Gunin et al., 1999). In Khangai and Altai Mountains, the dominant tree
species is Larix sibirica (accompanied by patches of Betula and Populus) on the northern and
eastern slopes, while steppe prevail the sun-exposed southern and western slopes (Miehe et
al., 2007). The uppermost boundary of the alpine meadows is ~ 2,900 m a.s.l. (Lehmkuhl and
Lang, 2001). Most of the lowland regions in the basin system are characterized by open desert
17
steppes and bare gobi surface. Dwarf bushes and reed-halophytes are the dominant
communities in lower reaches of the Orog Nuur catchment (Murad, 2011), while, as outlined
in Fig. 5-1A, the higher elevated catchment of the Orog Nuur is covered by forest steppe and /
or alpine steppe.
2.4. Paleo- and modern glacial setting
As illustrated in Fig. 2-4, there is no modern glacier or periglacial activity in the Ejina Basin,
albeit glaciers exist in the further southern higher elevated Qilian Mountains. On the other
hand, as the depositional basin of Orog Nuur is linked to the higher Khangai Mountains via
Tuyn Gol, Quaternary glacial variance may play a pivotal role in terms of water supply and
the clastic delivery. In modern times, only the western Khangai has small ice caps and the
average equilibrium line altitude (ELA) was estimated in a range from 3,900 to 4,000 m a.s.l.
(Fig. 2-4; Rother et al., 2014). The modern periglacial zone reaches down to 2,700 m a.s.l.
(Lehmkuhl and Lang, 2001; Klinge et al., 2003). A set of Last Glacial Maximum (LGM)
moraines at an altitude of ~2900 m. a.s.l. in the southern Khangai Mountains was dated
thereafter to >21 ka (Lehmkuhl and Lang, 2001). In addition, Ritz et al. (2006) determined
ages of alluvial sediments of the forelands of Gurvan Bogd (bogd = massif) by 10
Be
cosmogenic nuclides exposure dating and supposed an aggradation of sediments in the
context of the global glacial terminations. In the Gobi Altai, permafrost developed at ca. 22-
15 ka and degraded since ~13 ka, and was thereafter diminished since the early Holocene
(Owen et al., 1998).
2.5. Anthropo-zoogenic setting
In Neolithic period, first signs of nomadic presence on the NE Tibetan Plateau were reported
to be as early as 7,200 cal a BP, when temperature was up to 2 °C warmer than today (Schlütz
and Lehmkuhl, 2009). The descendant nomadic migration routes were established at least at
~2,200 years BP (Schlütz and Lehmkuhl, 2009). The “Nomadic Anthropocene” was
postulated by Schlütz and Lehmkuhl (2009) and Miehe et al. (2014) for the last 6,000 years
when nomads transformed the natural steppe-like vegetation into K. pygmaea pasture.
Landforms become more heterogeneous due to fragmentation of the rangelands (Yu et al.,
2017). Furthermore, in this region, agriculture facilitated permanent settlements were
suggested since 3,600 a BP (Chen et al., 2015). In modern times, human activities play an
important role in regulating the desert-steppe biomes in northern China and central to
southern Mongolia (Lehmkuhl, 1997). However, in our context, the time spanning of ~50 ka
18
to the early Holocene has ruled out intensively anthropo-zoogenic impacts, the reversed
thermal and moisture data indicate therefore exclusively paleoenvironmental signals.
Fig. 2-4: Schematic north-south oriented topographic transect and corresponding vegetation
patterns. The eastern parts of Khangai Mountains (higher reach of the Orog Nuur catchment)
with altitudes between 3,500 m and 3,700 m a.s.l. have no modern glaciers, while small ice-
fields may reach down to 3,200 m a.s.l. in the western Khangai Mountains (Lehmkuhl and
Lang, 2001).
19
“Paleoclimatic research provides the essential
understanding of climate system variability, and its
relationship to both forcing mechanisms and feedbacks,
which may amplify or reduce the direct consequences of
particular forcings…the proxy material has acted as a
filter, transforming climatic conditions at a point in time,
or over a period, into a more or less permanent record,
but the record is complex and incorporates other signals
that may be irrelevant to the paleoclimatologist”
(Raymond S. Bradley, 1999)
3. Materials and methods
3.1. Field work and sampling strategy
In the Ejina Basin, three field investigations were carried out in 2011, 2012 and 2014.
Selected profile locations are distributed along three geomorphological systems (Figs. 2-2),
i.e., following inverted channels (sections KK1 and KK2) to the lower Juyanze playa (section
HC8) and then toward the higher Wentugaole / Badain Jaran Desert margin (sections WT1
and WT2, see cross-section Fig. 4-1B). Ninety-three samples from five sections with different
geomorphological contexts were collected for further sedimentological and geochemical
analysis. Samples were acquired at 10-50 cm intervals based on stratum thickness and
properties. Fewer samples were acquired within the generally homogeneous lithological units.
Concerning the Orog Nuur, two parallel cores (ONW I: 6.00 m, 45°03’48”N, 100°34’39”E;
ONW II: 13.35 m, 45°04’28”N, 100°35’08”E, 1,219 m a.s.l.) are retrieved from the western
part of Orog Nuur during the playa phase in 2007 (Fig. 2-3). The core was opened, described
and documented in the field. Samples were separated and transported to University of
Göttingen, Free University of Berlin and the Alfred Wegener Institute in Bremerhaven for
palynological, ostracod, X-ray fluorescence and X-ray powder diffraction analyses. The
remaining material of the cores is preserved at RWTH Aachen University for grain size and
TOC analysis. The paleoenvironmental reconstruction is carried out primarily based on the
longer core ONW II.
20
3.2. Laboratory methods
3.2.1. Chronological methods
For the Ejina sequences, in order to acquire and assess a generally constrained chronological
framework which can be compared with previously established lacustrine or beach bar
records, AMS radiocarbon dating was applied to six samples in the Poznan Radiocarbon
Laboratory, Queen’s University Belfast and the Beta Analytic Radiocarbon Dating
Laboratory. Dated materials were bulk organic matter and carbonates. Radiocarbon ages were
calibrated to calendar years using the CALIB rev.7.1 (Stuiver et al., 1998) with the latest
calibration dataset (Intcal13.14c, Reimer et al., 2013). Radiocarbon ages are presented as
calibrated years (cal BP) unless otherwise noted. Optically Stimulated Luminescence (OSL)
dating was applied to six samples at Nanjing University. The samples were treated with 30 %
hydrogen peroxide and 10 % hydrochloric acid. The fine sand-sized (63-90 µm) quartz grains
were extracted by wet sieving. 2.58 g/cm3 sodium polytungstate was used to separate the
quartz and K-feldspar. Treatments with 40 % hydrogen fluoride for 40 min and 10 %
hydrochloric acid for 20 min were applied to purify the quartz. After washing and drying, the
grains were mounted as monolayer on the 9.8 mm diameter stainless steel discs using silicon
spray. All luminescence measurements were carried out using a Risø TL/OSL-DA-20 C/D
reader equipped with blue LEDs (470±30 nm) and an IR laser diode emitting at 830 nm
(Bøtter-Jensen et al., 2010). Irradiations were carried out with 90
Sr/90
Y beta sources mounted
on the readers and calibrated for discs. The quartz OSL signals were collected through 7.5
mm of Schott U-340 (UV) glass filter. Equivalent dose (De) was determined by single-aliquot
regenerative does (SAR) protocol following Murray and Wintle (2003). For samples with
feldspar contamination after a maximum of three etching treatments with hydrofluoric acid,
infrared IR-stimulation is inferred prior to the optical (blue-light) stimulation to both measure
and deplete the feldspar signal prior to the OSL measurement. A preheat of 260 °C for 10 s
and cut heat of 220 °C combination was used for routine equivalent dose measurements. The
238U,
232Th and
40K concentrations were detected using Neutron Activation Analysis (NAA) at
the China Institute of Atomic Energy. As the in-situ water content is extremely low, 25 % of
saturation water content was used in dose rate calculation and the absolute uncertainty on the
water content was assumed to be ±5%. Using the revised dose rate conversion factors of
Guérin et al. (2011) and water content attenuation factors (Aitken, 1998), the elemental
concentrations were converted into effective dose rate. The cosmic ray dose rate was
calculated following Prescott and Hutton (1994).
21
Concerning Orog Nuur drilling cores (ONW I; ONW II), ten radiocarbon ages were
determined from bulk materials (Tab. 5-1) using accelerator mass spectrometry (AMS) at the
University of Erlangen-Nürnberg and subsequently calibrated to calendar years using CALIB
rev. 7.1 (Stuiver et al., 1998) with the latest IntCal 13.14c calibration curve (Reimer et al.,
2013). All radiocarbon ages are presented as calibrated years (cal a BP). Apart from the
unrecovered uppermost sediments, a polylinearly regressed age-depth model of core ONW II
(25-1,335 cm) was computed. Reservoir effects at different depth are assessed by (i)
calculating the surface age from the age model, (ii) identifying Termination I in bulk-
geochemical and palynological sequences, and (iii) comparing the Younger Dryas (YD,
Dansgaard et al., 1989)-related sand layer in Orog Nuur and Ulaan Nuur (Fig. 5-1A, ~200 km
northeast of Orog Nuur, Lee et al., 2011, 2013). Two radiocarbon ages from core ONW I (at
386 cm and 588 cm, respectively) are employed to compare timing of the stratigraphic units
relative to ages of counterpart depths in core ONW II (Tab. 5-1 and Fig. 5-4).
3.2.2. Grain size analysis
The grain size distributions (GSDs) of all samples from the Ejina Basin and Orog Nuur Basin
were measured using a Beckman Coulter LS13320 Laser Diffraction Particle Size Analyzer
with a detection range of 0.04-2,000 µm. Portions larger than 2,000 µm were previously
removed by sieving. As previously proposed, the GSD, in particular the finer proportions (i.e.,
< 2 µm) in sand and loess sediments, may be potentially altered by different pretreatment
methods (e.g., Lu et al., 2001; Kovács, 2008; Mason et al., 2011). Therefore, before
measuring, a parallel test (HCl/H2O2- and H2O2-only-treatment) was done to test the impact of
possible incorporated calcium carbonate on the resulting GSD, revealing however no
pronounced differences (cf. Schulte et al., 2016). Thus, all measurements were performed
uniformly without hydrochloric acid treatment. 700 µl of 35 % H2O2 was added to remove the
organic components. Afterwards samples were dried at 70 °C for two days. Sodium
pyrophosphate was added to avoid coagulation. Optical properties (fluid RI = 1.33, sample RI
= 1.55, imaginary RI = 0.1) were used as described in Özer et al. (2010) for quartz dominated
samples. The final GSD represents the average of two subsamples. Each of them was
measured twice to ensure the reliability of the results. In case of conspicuous offset existing
between subsamples, the aforementioned procedure was repeated for the sample.
22
3.2.3. X-ray fluorescence analysis and X-ray diffraction
For those samples from the Ejina Basin, X-ray fluorescence (XRF) analysis was conducted at
RWTH Aachen University on all ninety-three samples using an Ametek X-ray Fluorescence
Spectrometer (Spectro Xepos, 2007). The whole sample material was dried, sieved through a
2,000 µm mesh sieve and then ground to < 63 µm using a Pulverisette 7 before mixing 8 g
sample with 2 g wax. The mixed powder is pressed into steel rings for measuring with a
pressure of 15 tons for 20 s. Following calculation procedure, root mean square errors of
calibration and lower limit of detection can be inferred from Spectro Xepos (2007). Certified
reference materials involving No. 5358-90, Nos 2504-2506-83, Nos 2498-2500-83, NCS DC
73375, JF-1, UG-QLO-1 and UG-SDC-1 were referred to during the analyzing. Thirty
elements are selected for further analysis. However, several values of the samples were below
detection limit (BDL). X-ray diffraction (XRD) was applied on fifty-three samples from
section HC8 to determine mineral abundances (Hartmann and Wünnemann, 2009). The XRD
was measured at Freie Universität Berlin using a Philips PW1710 and graphite
monochromator with a Cu-K-alpha at 36 kv, 24 mA. The powdered samples were scanned
from 3° to 40° at °2θ, angle spectrums are conducted by Xpert Highscore software, the
classification of impulses rates following Hartmann and Wünnemann (2009). Examples of
dispersive spectrums of XRD are illustrated in Fig. 4-4.
Concerning the Orog Nuur core sequences, the X-ray fluorescence (XRF) analysis was carried
out in Alfred Wegner Institute (AWI) for Polar and Marine Research in Bremerhaven,
Germany, using an Avaatech XRF Core Scanner configured with Canberra X-Pips 1500-1.5
detector (slit 10 mm, 10, 30 keV, 300 and 700 µA). The scanning interval is 1 cm, resulting in
1,335 measurements for the core ONW II. Processes comprising subtracting a background
curve, applying statistical corrections for physical processes in the detector and deconvolution
of overlapping peaks were performed using scanner equipped WinAxil package (NIOZ and
Avaatech, 2007). To gain a direct knowledge about the depositional environment of former
sediment-water interface, two factors were computed based on the element dataset using
factor analysis given in Yu et al. (2016). Thereby, high loading elements for each factor in
conjunction with the factor scores provide intriguing information about the sedimentary
processes (Yu et al., 2016). In addition, X-ray diffraction (XRD) for 14 samples at different
depths was performed to assess the general mineral composition and provide additional
information for the interpretation of bulk elemental compositions. The sediment color (RGB
model) was scanned using a CCD line scan camera.
23
3.2.4. Electrical conductivity and magnetic susceptibility measurements
For the core ONW I from the Orog Nuur, electrical conductivity (EC, here equals specific
conductivity) and magnetic susceptibility (MS) were carried out as an environmental and
salinity proxies. 50 ml water and 0.01 g KCl were added for each sample, the EC with 10 cm
interval was measured after 30 min using a WTW LF 196 probe. MS at 1 cm interval was
measured using a Barrington MS2 with a MS2 E sensor.
3.2.5. Carbon, nitrogen, sulfur, TOC and CaCO3 analyses
For the core ONW II from the Orog Nuur, Carbon (TC), nitrogen (TN), sulfur (TS)
concentrations, and the Total Organic Carbon (TOC) content were determined, in order to
gain a better understanding of the geochemical habitats of the former water sediment
interface. Samples were dried at 36 °C for 24 hours. The samples in zinc capsules were
subsequently analyzed in CHNS Analyzer EA3000. The Scheibler gas method (DIN 19684)
was employed to calculate the CaCO3 content, and 1-5 g samples were utilized respectively.
Calculation equation is as follows:
𝐶𝑎𝐶𝑂3 (%) = 𝑉 ∗ 𝑝 ∗ 0.1602/(𝑡 + 273) ∗ 𝐸 ∗ 𝐾
Where V is the volume of CO2 (cm3), p represents the atmospheric pressure (mm Hg), t
denotes room temperature (°C), E is the loss of weight (g) and K exhibits the correction factor
(here 2 is used). TOC was subsequently computed following Scheffer and Schachtschabel
(2002):
𝑇𝑂𝐶 = (𝐶 − (𝐶𝑎𝐶𝑂3 ∗ 0.12)) ∗ 1.72
The C/Natomic ratios throughout the ONW II core were computed and examined for further
interpretations (Meyers and Teranes, 2001).
3.2.6. Pollen, non-pollen palynomorphs and palynofacies analyses
Concerning the core ONW II, palynological studies were processed at University of
Göttingen. Sediment subsamples of 1 or 2 cm3 were acquired at 5-10 cm intervals through the
core ONW II. In total 123 samples were extracted and treated with standard laboratory
procedures including KOH, HCl, HF treatments and subsequent acetolysis (Erdtman, 1960;
Moore et al., 1991). Lycopodium spores were added as marker before calculation of the
24
pollen, spores and charcoal particle concentration (grains/cm3). Except for few samples, at
least 400 grains were counted for statistics. A total of 50 pollen and 40 spore taxa were
identified through the core ONW II. Clump of pollen that denotes immature grains sticking
together was calculated as paleoecological signals (Schlütz and Lehmkuhl, 2007). Available
references (Moore et al., 1991; Vanky, 1994; Van Geel et al., 2003) were employed to
identify the taxonomic nomenclature of pollen and spores. All taxa were subsequently
aggregated into several groups, namely, arboreal plants, humidity indicators, aquatic algae,
aridity indicators and grazing indicators. Two ratios were employed to compute the annual
temperature (T) and moisture (M) following Ma et al. (2008) (flora groups and equations see
Tab. 5-2). The moisture and thermal signals are further compared with the A/C ratios as well
as the pollen concentration, respectively.
3.2.7. Ostracod analysis
A total of 131 sub-samples from core ONW II were collected at 10 cm intervals for ostracod
analysis in order to examine and verify the paleohydrological conditions. The sediment was
treated with 3 % H2O2 for 48 hours and washed through 0.25 and 0.1 mm meshes. All
ostracod valves were picked from the dried sieve residues and identified according to Meisch
(2000) and Mischke and Zhang (2011). The species-specific ecological inferences are mainly
based on Hiller (1972), Hammer (1986), Anadon et al. (1994), Meisch (2000) and Mischke et
al. (2005).
3.3. Mathematical methods: Correlations and multivariate statistics
Data mining is an indispensable and vital step in trying to better understand intriguing
infomation in the bulk-geochemistry of the different sediment archives. Here, correlation
analysis and multivariate statistics (factor analysis) are computed. Multivariate statistics are
employed in both Chapters 4 and 5, while correlations analysis was only performed in
Chapter 4.
To provide an aid to illustrate the elemental characteristics of each archive type (see
conceptual model in Fig. 4-5), Spearman’s rank correlation was performed between GSD
proportions and XRF dataset (as a data set is not normally distributed, Spearman’s rank is
preferred to be conducted, see Spearman, 1904). In order to simplify interpretation of the
geochemical data (Fig. 4-5), a robust Factor Analysis (RFA) (Filzmoser et al., 2009; Zhang et
al., 2014a) was conducted on the whole multivariate dataset of ninety-three samples with
25
sixteen elements. Elements showing virtually all concentrations below the respective
detection limit or depicting low loadings in the conventional factor analysis were excluded.
Rarely occurred values lying below the detection limit are regarded as missing values (or
N/A) and will hinder the FA analysis (no zero value is allowed). They are therefore
substituted with ½ the lower detection limit (cf., IJmker et al., 2012b). Since the geochemical
dataset is sum-constrained and however not normally distributed, isometric log-ratio
transformation (Egozcue et al., 2003, and literature therein; Filzmoser et al., 2009) has been
applied, and the axis is rotated to the maximum direction of variance (i.e., varimax rotated
axis; Kaiser, 1958). Subsequently, the number of factors for interpretations needs to be
determined. Parallel analysis (Franklin et al., 1995) was performed and shows the first four
factors are higher than the parallel confidence. Thus, they are regarded as confident factors.
To further evaluate the overall quality of the analysis, communalities are computed by
summing up the squared loadings for each element (> 0.9 represent good representation for an
element).
Hereby, most of the original data characteristics are summarized in fewer decorrelated factors.
Cosine of the angle between the elements and the attribute- and factor-axis denote the loading
of this element on the factor (e.g., 45° represent the loading of 0.7), thus, the factor-loading-
matrix (eigenvector matrix) can be regarded as a correlation matrix for partial correlation of
input variables to factor ensemble (eigenspace bases). Sedimentary interpretations for each
factor can be inferred from corresponding higher loadings of specific elements. Factor scores
of each sample were obtained for detailed discussions of sedimentary processes (Fig. 4-5).
26
“The stratigraphic record of sedimentary rocks is the
fundamental database for understanding the evolution of
life, plate tectonics through time and global climate
change” (Gary Nichols, 2009)
4. Discriminating sediment archives and sedimentary processes in the arid endorheic
Ejina Basin, NW China using a robust geochemical approach (Published in 2016, Journal
of Asian Earth Science 119, 128-144)
Kaifeng Yu 1*
, Kai Hartmann 2, Veit Nottebaum
1, Georg Stauch
1, Huayu Lu
3, Christian
Zeeden 1, Shuangwen Yi
3, Bernd Wünnemann
2,3, Frank Lehmkuhl
1
1 Department of Geography, RWTH Aachen University, Templergraben 55, 52056 Aachen,
Germany
2 Department of Earth Sciences, Freie Universität Berlin, Malteserstraße 74-100, 12249
Berlin, Germany
3 School of Geographic and Oceanographic Sciences, Nanjing University, Xianlin Avenue
163, 210023 Nanjing, China
Geochemical characteristics have been intensively used to assign sediment properties to
paleoclimate and provenance. Nonetheless, in particular concerning the arid context, bulk
geochemistry of different sediment archives and corresponding process interpretations are
hitherto elusive. The Ejina Basin, with its suite of different sediment archives, is known as
one of the main sources for the loess accumulation on the Chinese Loess Plateau. In order to
understand mechanisms along this supra-regional sediment cascade, it is crucial to decipher
the archive characteristics and formation processes. To address these issues, five profiles in
different geomorphological contexts were selected. Analyses of X-ray fluorescence and
diffraction, grain size, optically stimulated luminescence and radiocarbon dating were
performed. Robust factor analysis was applied to reduce the attribute space to the process
space of sedimentation history. Five sediment archives from three lithologic units exhibit
geochemical characteristics as follows: (i) aeolian sands have high contents of Zr and Hf,
whereas only Hf can be regarded as a valuable indicator to discriminate the coarse sand
proportion; (ii) sandy loess has high Ca and Sr contents which both exhibit broad correlations
with the medium to coarse silt proportions; (iii) lacustrine clays have high contents of felsic,
ferromagnesian and mica source elements e.g., K, Fe, Ti, V, and Ni; (iv) fluvial sands have
27
high contents of Mg, Cl and Na which may be enriched in evaporite minerals; (v) alluvial
gravels have high contents of Cr which may originate from nearby Cr-rich bedrock. Temporal
variations can be illustrated by four robust factors: weathering intensity, silicate-bearing
mineral abundance, saline / alkaline magnitude and quasi-constant aeolian input. In summary,
the bulk-composition of the late Quaternary sediments in this arid context is governed by the
nature of the source terrain, weak chemical weathering, authigenic minerals, aeolian sand
input, whereas pedogenesis and diagenesis exert only limited influences. Hence, this study
demonstrates a practical geochemical strategy supplemented by grain size and mineralogical
data, to discriminate sediment archives and thereafter enhance our ability to offer more
intriguing information about the sedimentary processes in the arid central Asia.
4.1. Introduction
The main factors controlling geochemical compositions of sediments are the nature of parent
rocks, chemical weathering, diagenesis, mechanical disaggregation and abrasion, authigenic /
allothigenic input, and metamorphism in case of relatively old e.g., early Cenozoic and
Mesozoic sediments (Bhatia, 1983; Johnsson, 1993; Fralick and Kronberg, 1997; Young et
al., 1998; McLennan, 2001; S. Yang et al., 2004; Xu et al., 2011). Analyzing geochemical
characteristics along with other characteristics of sediments is therefore a powerful tool to
better decipher the nature of aforementioned processes. Previously, elemental (isotopic) and
mineral fingerprints have been employed to evaluate the provenance of the American loess /
mudstones / sandstones (Gallet et al., 1998; Zhang et al., 2014b), European loess (Amorosi et
al., 2002; Buggle et al., 2008; Újvári et al., 2014), Eastern / Central Asian loess / desert sands
(Liu et al., 1993; Honda and Shimizu, 1998; Jahn et al., 2001; Honda et al., 2004; Yang et al.,
2007; Maher et al., 2009; Stevens et al., 2010; Chen and Li, 2011; Xu et al., 2011; Xiao et al.,
2012; Wang et al., 2012) and Greenland dust (Újvári et al., 2015). Nesbitt and Young (1982)
reported the major element content to represent a quantitative chemical weathering proxy,
whereas in absence of strong chemical weathering (e.g., in arid and semi-arid environments,
Zhu et al., 2014), the bulk-composition and mineralogy can be explained by physical
abrasion, comminution and sorting (Nesbitt and Young, 1996; von Eynatten et al., 2012).
Elemental characteristics of lacustrine or aeolian deposits have been employed to reconstruct
the paleoenvironmental change in the northern Tibetan Plateau and the Mongolian Plateau
during the late Quaternary (e.g., Hartmann and Wünnemann, 2009; Schwanghart et al., 2009;
Lu et al., 2010; IJmker et al., 2012a; Felauer et al., 2012; Guo et al., 2013). Apart from
provenance and paleoenvironmental studies, the nature of bulk-compositions of different
28
sediment archives is hitherto incompletely understood. On the other hand, whether and how
geochemical composition can be assigned to sedimentary processes in arid region is seldom
studied. To further disentangle the past processes and controlling factors, a better
understanding of the geochemical fingerprints recorded in these archives is needed.
In arid and semi-arid areas, particularly, in basin systems, lacustrine, aeolian and alluvial /
fluvial sediments are common. Spatial and temporal characteristics of these sediments are
correlated to littoral and pelagic deposition systems of paleolake expansion and desiccation
(e.g., Wünnemann, 1999; Shanahan et al., 2013), which can be ascribed to climatic variations.
The endorheic Ejina Basin is regarded as a fundamental dust provenance of the Chinese Loess
Plateau and adjacent regions (Pye and Zhou, 1989; Lu and Sun, 2000; Vandenberghe et al.,
2006; Sun et al., 2008). Deciphering the geochemical characteristics of archives in the basin
system is one crucial step towards a better understanding of the sedimentary processes related
to dust activity.
In this study, a geochemical approach in conjunction with a broad field of granulometric,
mineralogical and generally constrained chronological data is presented in order to:
(1) Identify the broad pattern of lithologic units at the northern margin of the Ejina Basin.
(2) Differentiate the distinct nature of bulk-compositions in different granulometric
compositions and the array of archives obtained from these units.
(3) Employ a multivariate statistic approach to test which assemblages of elements are
suitable, sensitive and robust to reconstruct sedimentary processes and thereby to evaluate
the controlling factors for the bulk-composition of sediments in (semi-)arid regions.
Hence, ultimately, the aim is to improve our understanding of the intriguing sedimentary
processes in this arid terrestrial endorheic context.
29
Fig. 4-1: Simplified geologic map and section locations in the northern Ejina Basin: (A)
Section HC8 is an escarpment between the western and eastern Juyanze sub-basin. Sections
KK1 and KK2 are located by the braided river channel near ancient of Khara Khoto. Sections
WT1 and WT2 are yardangs located on the margin of Wentugaole Sub-basin and Badain
Jaran Desert. Black (dash-) lines denote strike-slip neotectonics compiled from Wünnemann
et al. (2007), Hölz et al. (2007), Hartmann et al. (2011), Cunningham (2013) and Rudersdorf
et al. (2015). Black bold lines denote schematic elevation cross-section in panel B. D100
correspond to the drilling core from Wünnemann, 1999 and Wünnemann et al., 2007. (B)
Cross-section from Khara Khoto to Juyanze (playa) and Wentugaole (sub-basin).
30
4.2. Regional Setting
The Ejina Basin (synonym: Gaxun Nur Basin) is located in the lower reaches of the endorheic
Hei River catchment (with an area of ca. 130,000 km2, Fig. 4-1), which contains one of the
world’s largest continental alluvial fan systems (Hartmann et al., 2011). The basin covers an
area of about 28,000 km2
and is fed by the Hei River discharging from the Qilian Mountains.
The elevation ranges from 880 to 1,300 m above sea level (a.s.l.) (Hartmann et al., 2011) and
late Quaternary sediments are up to ~300 m thick (Zhang et al., 2006; Hartmann and
Wünnemann, 2009). The infilling of the basin started probably at earliest 250 ka ago, as
retrieved from the D100 drilling core (Fig. 4-1, 42.1°N 100.85°E, 940 m a.s.l., Wünnemann,
1999, Wünnemann et al., 2007a). Paleozoic to Mesozoic intrusive bedrock can be observed in
the northern Juyanze and Wentugaole basins (Fig. 4-1, Becken et al., 2007; Rudersdorf et al.,
2015).
The basin as part of the Gobi Desert is located beyond the limits of the East Asian Summer
Monsoon (cf., Chen et al., 2008). The winter Siberian Anticyclone dominates the climate
regime (Chen et al., 2008; Mölg et al., 2013). The mean January and July air temperatures are
ca. -11°C and 26 °C, respectively. More than 90% of the ca. 38 mm annual precipitation occur
between July and early September, albeit the annual precipitation in the upper reaches of the
Hei River catchment in the Qilian Mountains can reach 300-500 mm (Wang and Cheng, 1999;
Wünnemann et al., 2007a). The theoretical potential evaporation is around 3,700 mm.
The basin is bound by the Heli Mountains in the south, the Bei Mountains to the west, the
Badain Jaran Desert / Alashan Plateau to the east and the Gobi Altai Mountains to the north
(Fig. 4-1). Temporal and spatial patterns of fluvial and lacustrine deposition are influenced by
neotectonics (e.g., the western margin has a subsidence rate of ca. 0.8-1.1 m/ka, cf., Hartmann
et al., 2011). Nowadays, only the Ejina oasis near Juyanze paleolake receives ephemeral water
input (Hartmann et al., 2011). Typical geomorphological features are gravel plains, yardangs,
playas, sand fields and sporadically distributed mobile linear and barchan dunes (Zhu et al.,
2014, Fig. 4-2).
31
Fig. 4-2: Photographs of representative geomorphological contexts from the northern Ejina
Basin: (A) Inverted channels near Khara Khoto. (B) Gobi surface and Precambrian intrusive
bedrocks in Wentugaole sub-basin. (C) Khara Khoto and nearby accumulated dunes. (D)
Yardangs in southern Wentugaole sub-basin. (E) Playa surface of western Juyanze Basin. (F)
Megadunes on the northern margin of Badain Jaran Desert.
4.3. Methods
4.3.1. Sampling strategy
Three field investigations were carried out in 2011, 2012 and 2014. Selected profile locations
are distributed along three geomorphological systems (Figs. 4-1B and 4-3), i.e., following
inverted channels (sections KK1 and KK2) to the lower Juyanze playa (section HC8) and then
toward the higher Wentugaole / Badain Jaran Desert margin (sections WT1 and WT2, see
32
cross-section Fig. 4-1B). Ninety-three samples from five sections with different
geomorphological contexts were collected for further sedimentological and geochemical
analysis. Samples were acquired at 10-50 cm intervals based on stratum thickness and
properties. Fewer samples were acquired within the generally homogeneous lithological units.
Fig. 4-3: Lithostratigraphy and generally constrained chronology framework. Chronology
framework is labeled, and 2-sigma ranges for calculated radiocarbon ages are reported in
Table 1. U1 is the lowermost aeolian sands (except for WT1), U2 is lacustrine stratum, and
U3 is fluvial sands (mixed with gravels) unit (e.g., Fig. 2A). U3 of HC8 is especially thick
mixture of poorly-sorted coarse alluvial sands and gravels.
4.3.2. Chronological methods
In order to acquire and assess a generally constrained chronological framework which can be
compared with previously established lacustrine or beach bar records, AMS radiocarbon
dating was applied to six samples in the Poznan Radiocarbon Laboratory, Queen’s University
Belfast and the Beta Analytic Radiocarbon Dating Laboratory. Dated materials were bulk
33
organic matter and carbonates. Radiocarbon ages were calibrated to calendar years using the
CALIB rev.7.1 (Stuiver et al., 1998) with the latest calibration dataset (Intcal13.14c, Reimer
et al., 2013). Radiocarbon ages are presented as calibrated years (cal BP) unless otherwise
noted.
Optically Stimulated Luminescence (OSL) dating was applied to six samples at Nanjing
University. The samples were treated with 30 % hydrogen peroxide and 10 % hydrochloric
acid. The fine sand-sized (63-90 µm) quartz grains were extracted by wet sieving. 2.58 g/cm3
sodium polytungstate was used to separate the quartz and K-feldspar. Treatments with 40 %
hydrogen fluoride for 40 min and 10 % hydrochloric acid for 20 min were applied to purify
the quartz. After washing and drying, the grains were mounted as monolayer on the 9.8 mm
diameter stainless steel discs using silicon spray. All luminescence measurements were
carried out using a Risø TL/OSL-DA-20 C/D reader equipped with blue LEDs (470±30 nm)
and an IR laser diode emitting at 830 nm (Bøtter-Jensen et al., 2010). Irradiations were
carried out with 90
Sr/90
Y beta sources mounted on the readers and calibrated for discs. The
quartz OSL signals were collected through 7.5 mm of Schott U-340 (UV) glass filter.
Equivalent dose (De) was determined by single-aliquot regenerative does (SAR) protocol
following Murray and Wintle (2003). For samples with feldspar contamination after a
maximum of three etching treatments with hydrofluoric acid, infrared IR-stimulation is
inferred prior to the optical (blue-light) stimulation to both measure and deplete the feldspar
signal prior to the OSL measurement. A preheat of 260 °C for 10 s and cut heat of 220 °C
combination was used for routine equivalent dose measurements. The 238
U, 232
Th and 40
K
concentrations were detected using Neutron Activation Analysis (NAA) at the China Institute
of Atomic Energy. As the in-situ water content is extremely low, 25 % of saturation water
content was used in dose rate calculation and the absolute uncertainty on the water content
was assumed to be ±5%. Using the revised dose rate conversion factors of Guérin et al. (2011)
and water content attenuation factors (Aitken, 1998), the elemental concentrations were
converted into effective dose rate. The cosmic ray dose rate was calculated following Prescott
and Hutton (1994).
4.3.3. Grain size analysis
The grain size distributions (GSDs) of all samples were measured using a Beckman Coulter
LS13320 Laser Diffraction Particle Size Analyzer with a detection range of 0.04-2,000 µm.
Portions larger than 2,000 µm were previously removed by sieving. As previously proposed,
the GSD, in particular the finer proportions (i.e., < 2 µm) in sand and loess sediments, may be
34
potentially altered by different pretreatment methods (e.g., Lu et al., 2001; Kovács, 2008;
Mason et al., 2011). Therefore, before measuring, a parallel test (HCl/H2O2- and H2O2-only-
treatment) was done to test the impact of possible incorporated calcium carbonate on the
resulting GSD, revealing however no pronounced differences (cf. Schulte et al., 2016). Thus,
all measurements were performed uniformly without hydrochloric acid treatment. 700 µl of
35 % H2O2 was added to remove the organic components. Afterwards samples were dried at
70 °C for two days. Sodium pyrophosphate was added to avoid coagulation. The Mie Theory,
instead of previously used Fraunhofer approximation (cf., Özer et al., 2010), is applied for
GSD calculations. Optical properties (fluid RI = 1.33, sample RI = 1.55, imaginary RI = 0.1)
were used as described in Özer et al. (2010) for quartz dominated samples. The final GSD
represents the average of two subsamples. Each of them was measured twice to ensure the
reliability of the results. In case of conspicuous offset existing between subsamples, the
aforementioned procedure was repeated for the sample.
35
Fig. 4-4: Example of wave-length dispersive spectrums of X-ray diffraction (XRD). Panels A
to E denote aeolian sands, lacustrine clay, fluvial sands, sandy loess, alluvial gravels,
respectively from section HC8 (with depth). The powdered samples were scanned from 3° to
40° at °2θ, angle spectrums are conducted by Xpert Highscore software, the classification of
36
impulses following Hartmann & Wünnemann (2009). The number of counts is illustrated as
reference for e.g., aeolian sands.
4.3.4. X-ray fluorescence analysis and X-ray diffraction
X-ray fluorescence (XRF) analysis was conducted at RWTH Aachen University on all ninety-
three samples using an Ametek X-ray Fluorescence Spectrometer (Spectro Xepos, 2007). The
whole sample material was dried, sieved through a 2,000 µm mesh sieve and then ground to <
63 µm using a Pulverisette 7 before mixing 8 g sample with 2 g wax. The mixed powder is
pressed into steel rings for measuring with a pressure of 15 tons for 20 s. Following
calculation procedure, root mean square errors of calibration and lower limit of detection can
be inferred from Spectro Xepos (2007). Certified reference materials involving No. 5358-90,
Nos 2504-2506-83, Nos 2498-2500-83, NCS DC 73375, JF-1, UG-QLO-1 and UG-SDC-1
were referred to during the analyzing. Thirty elements are selected for further analysis.
However, several values of the samples were below detection limit (BDL).
Fig. 4-5: Conceptual modal of the robust geochemical approach to discriminate archives and
sequence sedimentary processes.
X-ray diffraction (XRD) was applied on fifty-three samples from section HC8 to determine
mineral abundances (Hartmann and Wünnemann, 2009). The XRD was measured at Freie
Universität Berlin using a Philips PW1710 and graphite monochromator with a Cu-K-alpha at
36 kv, 24 mA. The powdered samples were scanned from 3° to 40° at °2θ, angle spectrums
are conducted by Xpert Highscore software, the classification of impulses rates following
37
Hartmann and Wünnemann (2009). Examples of dispersive spectrums of XRD are illustrated
in Fig. 4-4.
4.3.5. Correlations and multivariate statistics
To provide an aid to illustrate the elemental characteristics of each archive type (see
conceptual model in Fig. 4-5), Spearman’s rank correlation was performed between GSD
proportions and XRF dataset (as a data set is not normally distributed, Spearman’s rank is
preferred to be conducted, see Spearman, 1904).
In order to simplify interpretation of the geochemical data (Fig. 4-5), a robust Factor Analysis
(RFA) (Filzmoser et al., 2009; Zhang et al., 2014a) was conducted on the whole multivariate
dataset of ninety-three samples with sixteen elements. Elements showing virtually all
concentrations below the respective detection limit or depicting low loadings in the
conventional factor analysis were excluded. Rarely occurred values lying below the detection
limit are regarded as missing values (or N/A) and will hinder the FA analysis (no zero value is
allowed). They are therefore substituted with ½ the lower detection limit (cf., IJmker et al.,
2012b). Since the geochemical dataset is sum-constrained and however not normally
distributed, isometric log-ratio transformation (Egozcue et al., 2003, and literature therein;
Filzmoser et al., 2009) has been applied, and the axis is rotated to the maximum direction of
variance (i.e., varimax rotated axis; Kaiser, 1958). Subsequently, the number of factors for
interpretations needs to be determined. Parallel analysis (Franklin et al., 1995) was performed
and shows the first four factors are higher than the parallel confidence. Thus, they are
regarded as confident factors. To further evaluate the overall quality of the analysis,
communalities are computed by summing up the squared loadings for each element (> 0.9
represent good representation for an element).
Hereby, most of the original data characteristics are summarized in fewer decorrelated factors.
Cosine of the angle between the elements and the attribute- and factor-axis denote the loading
of this element on the factor (e.g., 45° represent the loading of 0.7), thus, the factor-loading-
matrix (eigenvector matrix) can be regarded as a correlation matrix for partial correlation of
input variables to factor ensemble (eigenspace bases). Sedimentary interpretations for each
factor can be inferred from corresponding higher loadings of specific elements. Factor scores
of each sample were obtained for detailed discussions of sedimentary processes (Fig. 4-5).
38
4.4. Results
4.4.1. Lithology and chronology
Radiocarbon (Tab. 4-1) and OSL ages (Tab. 4-2) provide a chronological framework for the
studied sections. In conjunction with field investigations and visual observations, three
lithologic units were recognized (Figs. 4-3 and 4-5): (i) U1, the lowermost facies of the
aeolian sands (except WT1) are dated to older than 200 ka BP according to OSL ages. (ii) U2,
the clay to silty-clay stratum are dated to start at around the early global LGM ca. 26 and ca.
32 ka BP (for stratigraphy and error ranges see Fig. 4-3 and Tab. 4-1, respectively). (iii) U3,
the uppermost poorly-sorted mixture of coarse sands and angular gravel strata are dated to
start at around ca. 14 to 25 ka BP. The purported age difference resulting from the
chronological methods falls out of the scope of this study (Zhang et al., 2006; Long and Shen,
2015). In addition, two sand samples from yardangs (corresponding to U1) in Wentugaole
were obtained to test the feldspar dating performance. They yielded saturated equivalent doses
as well. The section with the probably most complete sediment stratum, HC8 (Figs. 4-1 and 4-
3), will be discussed as the key profile to assess the capability to reconstruct the sedimentary
processes. Brief section descriptions are provided subsequently.
Tab. 4-1: Results of the AMS 14
C-dating. Radiocarbon ages were calibrated to calendar years
with 2 σ standard deviation using the CALIB rev.7.1 (Stuiver et al., 1998) with the latest
calibration dataset (Intcal13.14c, Reimer et al., 2013).
Location Section
name
Lab.-No. Depth/cm Dating
material
Δ13C TOC/mg Age /ka BP 2 σ/cal ka BP
(95.4 %)
Khara Khoto KK2 Poz-53749 50 Bulk material - 0.15 11.82±0.13 13.73±0.29
Khara Khoto KK2 Poz-53750 120 Bulk material - 0.19 20.36±0.22 24.56±0.59
Khara Khoto KK1 UBA-19486 U. surface Bulk material -23.6 - 23.87±0.14 28.09±0.17
Wentugaole WT1 Poz-53751 470 Bulk material - 0.70 28.41±0.20 32.30±0.67
Wentugaole WT1 Poz-53752 350 Bulk material - 0.20 21.26±0.21 25.42±0.27
Juyanze HC8* Beta-190785 502 Bulk organic carbon
-22.8 - 15.06±0.80 18.29±0.24
* HC8 radiocarbon age was published in Hartmann & Wünnemann, 2009.
HC8 (41.9023°N, 101.7578°E, 934 m a.s.l.) represents a 13 m escarpment. Below 9 m, the
section exhibits loose fine sand with increasing silt contents up to 8 m. 8-2.5 m (base of U2)
show slightly indurated silty clay material. Sandy loess-like material was observed in depths
of ca. 3.5-3.0 m. 3.0-0 m is represented by a poorly-sorted mixture of coarse sands and
gravels.
KK1 (41.7494°N, 101.1582°E, 952 m a.s.l.) is located in an outcropping inverted channel
near the ancient city of Khara Khoto / Black City (Fig. 4-1). Coarse sand prevails below 3.1
39
m, overlain by a cemented mixture of coarse sand and pebbles (3.1-2.5 m). Layers of fine to
medium sand were preserved from 2.5 to 1.7 m, sand ripple structures and root channels were
sporadically exhibited. Deposits from 1.7 to 0.1 m (U2) were weakly indurated clayey to silty-
clayey sediments. The surface (0.1-0 m, U3) is covered by set of gravels with largest
diameters of ca. 70 mm and mixed with coarse sand.
KK2 (41.7563°N, 101.1255°E, 953 m a.s.l.) is in the vicinity of section KK1 (see Fig. 4-1).
U1 is represented by heterogeneous laminae of sand layers (3.2-1.25 m). U2 (1.25-0.2 m) is a
slightly reddish clayey to silty-clayey stratum. The surface, representing U3 (0.3-0 m),
consists of slightly indurated sand.
WT1 (41.3559°N 102.2468°E, 967 m a.s.l.) reflects a ca. 6 m yardang feature located on the
northern margin of the Badain Jaran Desert (Wentugaole Basin). Indurated clayey to silty-
clayey sediments were recovered below 5.4 m. 5.4-4.9 m is represented by diagonally cross-
bedded silt to sand with interbedding gypsum crusts. It is comparably thin in regard of the
other sections’ U1 unit. U2 (4.9-0.2 m) is clayey sediment while the surface (U3, 0.2-0 m) is
composed of strongly cemented coarse sand.
WT2 (41.3593°N 102.2456°E, 960 m a.s.l.) is a yardang record adjacent to WT1. Between
7.75 and 7.70 m horizontally layered sand was recovered, which is interrupted by a 5 cm thick
whitish-grayish laminated clay layer (7.75-7.70 m). The base of U2 is represented by a 5 cm
thick laminated clay layer (7.05-7.00 m), while up to 0.10 m the deposit is homogeneous clay.
The overlying U3 is an indurated white to greenish sandstone.
Tab. 4-2: Summary of water content, equivalent dose value (De), dose rate, number of used
aliquots and luminescence ages of samples from study sections. 238
U, 232
Th and 40
K
concentrations were determined by Neutron Activation Analysis (NAA). Absolute uncertainty
of the water content was assumed to be < ±5%. Due to saturation of the equivalent dose, brief
constrained luminescence ages are presented here. More details concerning the method see
Chapter 4.3.2.
Locati
on
Sectio
n
Lab.-No. Dept
h/cm
Water
/%
238U/pp
m
232Th/p
pm
40K/% De/Gy Dose rate/Gy
ka-1
Aliquots
number
Age/ka
Khara
Khoto
KK2 NJU1365 145 6 0.99±0.05
3.97±0.05
1.43±0.05
˃310 2.06±0.21 8 ˃150
Khara
Khoto
KK2 NJU1364 307 6 0.93±0.
05
3.70±0.
05
1.32±0.
05
˃400 1.90±0.20 3 ˃200
Wentu
gaole
WT1 NJU1366 500 4 0.76±0.
05
2.73±0.
05
1.31±0.
05
˃280 1.80±0.20 5 ˃158
Wentu
gaole
WT2 NJU1367 765 7 0.81±0.05
3.03±0.05
1.44±0.05
- - 6 Saturated
40
4.4.2. Granulometric composition and pre-assessment of archives
Grains size distributions (GSDs) are divided into six fractions as described in Blott and Pye
(2012): Clay (0.04-2 µm), fine silt (2-6.3 µm), medium silt (6.3-20 µm), coarse silt (20-63
µm), fine sand (63-200 µm), medium sand (200-630 µm) and coarse sand (630-2,000 µm).
Granulometric composition is illustrated in a ternary diagram (Fig. 4-6A).
Fig. 4-6: Ternary diagrams of granulometric properties and A-CN-K (molar proportions):
(A) Granulometric ternary diagram. (B) A-CN-K ternary diagram, CaO is corrected to
silicate carbonate following the procedure of McLennan (1993). The Chemical Index of
Alteration (CIA, Nesbitt & Young, 1982) is related on the right side of the A-CN-K triangle.
Abbreviations: A=Al2O3, C=CaO, N=Na2O, K=K2O, Ka=Kaolinite, Gi=Gibbsite,
Ch=Chlorite, Il=illite, Mu=muscovite, Pl=plagioclase, Bi=Biotite, Ks=alkali feldspar,
Ch=chlorite, Cp=clinopyroxene, Hb=hornblende.
For section HC8 (cf., Fig. 4-10): (i) most samples in lower U1 are characterized by unimodal
GSD curves and bimodal GSDs in the upper part. Clay proportion increases from 1.4 % to
18.9 % accompanied by an increasing silt proportion from 1.5 % to 24.5 %. Several coarse
sand input intervals can be detected in these layers. Clay and silt fractions share quite similar
depth patterns. Moreover, the medium sand proportion has the highest percentage (ca. 80 %)
at the bottom (ca. 13 m), whereas the upper part shows broadly less than 30 % with low
variance. (ii) U2 mostly consists of clay interbedded with coarse sand input. The clay
proportion varies between 15-40 %, silt proportion varies between 30-70 % and sand
proportion remains between 15-40 %. Generally, silt and sand proportions are increasing from
basal U2 to the upper part. (iii) The surface samples from U3 are predominantly unsorted silt
41
to sands mixed with angular gravels. In contrast, the other sections exhibit thinner U3 strata.
Regarding the other sections, broadly resembling GSD patterns throughout the profile can be
observed (Fig. 4-3; detail GSDs not illustrated).
Fig. 4-7: Granulometric properties of archives: (A) aeolian sands (n=51), (B) lacustrine clay
(n=19), (C) fluvial sands (n=18), (D) sandy loess (n=2), (E) alluvial gravels (n=2), different
axis scales are used.
42
Fig. 4-8: Spearman’s rank correlation coefficients between geochemical properties and grain
size parameters (all scales of red to blue units have passed 0.05 significant level). Not all
elements exhibit grain-size dependence (e.g., As, Nd, S and Al). Red pixels denote positively
correlated and blue ones depict negative correlations. These features can also shed light on
elemental characteristics of archives. C, fSi, mSi, cSi, fS, mS and cS denote the particle size of
clay, fine silt, medium silt, coarse silt, fine sand, medium sand and coarse sand, respectively.
According to the GSD patterns and the field investigation, all samples are differentiated into
five archive categories: aeolian sands, lacustrine clays, fluvial sands, sandy loess and alluvial
gravels (Fig. 4-5). The clusters of granulometric patterns are acquired as depicted in Fig. 4-7.
Combined with the criterion reported by Lu et al. (2001), Blott and Pye (2012), Vandenberghe
(2013) and Nottebaum et al. (2014), differentiation strategies are as follows: (i) aeolian sand
usually has a unimodal or sometimes bimodal distribution with a mode at around 50-250 µm
or even coarser (Fig. 4-7A); (ii) lacustrine clay usually shows bimodal or trimodal grain size
distribution including well sorted suspension proportions (8-9 µm) as the main mode (Fig. 4-
7B); (iii) fluvial sand’s GSDs are often polymodal, including a dominant well sorted saltation
portion (usually 250-400 µm) as the main mode and poorly sorted suspension proportions
(<63 µm) (Fig. 4-7C); (iv) sandy loess has a unimodal leptokurtic distribution and has a mode
43
around 60 µm (cf., end member 1 in Vriend and Prins, 2005; Prins et al., 2007; Nottebaum et
al., 2014, 2015b) and a minor population at around 2-15 µm (Fig. 4-7D); (v) alluvial gravels
have a unimodal distribution and a mode much larger than 1,000 µm (Fig. 4-7E).
4.4.3. Elemental and mineralogical composition of archives
In total thirty major and trace elements in ninety-three samples were acquired (Tab. 4-3). The
correlation coefficients between grain size proportions and element concentrations are
illustrated in Fig. 4-8.
Tab. 4-3: Results of the oxides of ten major elements expressed as normalized wt % and other
trace elements concentrations (ppm) of sediment archives as determined by X-ray
fluorescence analysis. Decimal precision of the reported concentrations were revised
according to the formats of their counterparts in the UCC data set (Rudnick and Gao, 2003).
Root mean square errors (RMS) and lower limit of detection (LOD) of each element see
Spectro Xepos (2007).
Element UCC* Factors Aeolian
sands
Lacustrine clay Fluvial sands Sandy loess Alluvial
gravels
SiO2 66.6 RF2 71.72 55.08 47.30 69.25 36.30
Al2O3 15.4 - 9.69 16.48 13.18 13.73 6.37
Fe2O3 5.04 RF1 2.96 7.53 5.58 4.95 2.18
MnO 0.1 RF2(-) 0.07 0.16 0.20 0.06 0.17
MgO 2.48 RF2(-) 4.50 7.07 11.63 3.72 7.96
CaO 3.59 - 6.11 6.77 15.40 2.00 42.64
Na2O 3.27 RF3 2.12 2.51 3.23 2.47 2.56
K2O 2.8 RF1 2.28 3.43 2.69 2.88 1.37
TiO2 0.64 RF1 0.39 0.81 0.63 0.74 0.28
P2O5 0.15 - 0.16 0.16 0.16 0.20 0.20
TOTAL - - 100 100 100 100 100
Rb 82 RF1 57 118 85 35 85
Y 21 - 11 23 20 17 17
V 97 - 67 142 102 28 116
Nb 12 - 4.1 10.1 7.1 2.3 9.4
Ni 47 - 23 60 42 9 39
Cu 28 RF1 12 39 28 8 27
Zn 67 RF1 26 92 67 23 54
Ga 17.5 RF1 8.0 19.4 14.2 5.8 13.3
Pb 17 - 11.6 29.1 22.7 10.5 18.3
As 4.8 - 5.6 19.4 10.9 4.6 11.7
Th 10.5 RF1 5.2 15.9 11.2 5.1 10.6
Sr 320 - 138 165 184 338 140
Cl 294 RF3 4052 6685 8513 1309 4615
S 621 - 785 2155 2194 935 2634
Cr 92 - 266 124 122 99 399
Zr 193 RF4 344 156 143 175 269
Hf 5.3 RF4 6.6 4.2 3.1 4.4 3.7
Nd 27 - 52 99 91 63 72
Ba 628 - 580 515 439 545 467
W 1.9 - 2.8 2.8 3.1 2.0 3.7
* UCC=Upper Crust Composition (Rudnick and Gao, 2003). Total iron expressed as Fe2O3.Ten major elements are expressed as oxides (wt
%), while other trace elements are expressed as ppm. The description of factors analysis refers to Tab. 4-4.
44
Fig. 4-9: Loading and score plot of geochemical data set: (A) Loading plot of conventional
factor analysis, with thirty elements. (B) Score plot of conventional factor analysis, with thirty
elements. (C) Loading plot of robust factor analysis, with sixteen elements. (D) Score plot of
the robust factor analysis, with sixteen elements. Originally, the maximum direction of
variance will be regarded as axes, however, rotation is performed to get varimax rotated axis
(i.e., X-and Y-axis here) during the factor analysis to provide a higher loading for each
elements (Tab. 4-4). Cosine of the angle between the elements arrow and the component
(varimax rotated axes) are factor loadings, length of the arrows are corresponding to the
element communalities. Compared with conventional factor analysis (Panels A and B), panels
C and D exhibit higher cumulative proportions for RFs 1 and 2. Dashed line circles in panels
A and C denote communality estimates (Tab. 4-4) and thereby assess the quality for each
45
element (> 0.9 can be regarded as good quality) in this factor modal. Panels B and D
illustrate that multivariate statistic of elemental fingerprints appears to be a practical method
to discriminate the archive types, of which mistakes may be yielded from field investigations
and GSD observations alone.
For samples from section HC8, minerals comprising quartz, feldspar, amphibole, clay
minerals, calcite, aragonite, dolomite, gypsum and halite abundances were determined.
Generally, the U1 stratum has higher contents of quartz and feldspar, the U2 stratum has
pronounced higher contents of clay minerals, gypsum and halite, and the U3 stratum has
especially high content of calcite. They therefore shed light on the mineralogical compositions
of archives, which will also aid the further interpretation of the XRF dataset.
4.4.4. Element assemblages and loadings as derived from conventional and robust factor
analysis
To gain an overview of the distribution of all thirty elements, conventional factor analysis was
done for all samples (Fig. 4-9A and 9B). Major and trace elements can be categorized into
several assemblages as follows: (i) cluster of elements such as K, Rb, Ti, V, Nb, Fe, Ni, Cu,
Zn, Al, Ga, As, Y, Nd, Pb and Th behave relatively similar with respect to convergence /
variation against depth and the directions generally point to factor 1 positively. In section
HC8, they have lower abundances in the basal U1 unit. Interestingly, there is one extremely
high value for all these elements at a depth between 943 and 959 cm. All these elements show
particularly low values in U3, accompanied by lower values in U1 and relatively higher
values in U2. (ii) Concerning Na, Cl and S, the former two elements have resembled variation
trends against depth. Three high value peaks within U2 can even reach 70,000 ppm for Na
and 55,000 ppm for Cl. S has a similar convergence zone as Na and Cl. Na and Cl show
slightly positive indications to both factor 1 and factor 2 (Fig. 4-9A). (iii) Si, Mg, Sr, Ca and
Mn show a similar distribution in Fig. 4-9A. Ca and Sr have relatively high values within U3,
whereas Mg exhibits extremely low contents in U3 (figures are omitted here). Mn is relatively
rare and commonly originates from highly soluble minerals (e.g., mobile Mn2+
) and occurs in
ultramafic rocks (e.g., dust transport of solid Mn3+
and Mn4+
, IJmker et al., 2012a), it exhibits
however higher concentrations in mixed fluvial sands (Tab. 4-3), the former process is thus
more likely the origin of Mn. In contrast, no dominant trends can be extracted from the
irregular variance of Si. All these elements show indications generally positive to factor 2 and
may be connected to fluvial archives (Fig. 4-9A and 9B). (iv) For Cr, Hf, Zr and Ba,
compared to U2, Hf and Zr values show remarkably higher contents in aeolian sands (U1). Cr
46
shows much more sensitive variations to the aeolian input, whenever aeolian sand input
occurs. The Cr values are approximately three times higher than the neighboring sample
values. Meanwhile, Ba values show irregular variances and no trend can be figured out. All
Cr, Hf, Zr and Ba values show negatively correlations to factor 2 (Fig. 4-9A). (v) P and W
show slightly positive loadings to both factors 1 and 2, no dominant trend can be extracted
from their irregular variance. Thus, they were excluded from further discussions.
Tab. 4-4: Standard deviations, variance / cumulative proportions, element loadings for each
factor, and communalities for each element. High positive or negative (>0.75) loadings are
shown in boldface, proportions in %.
Elements RF1, Weathering
intensity
RF2, Silicate-bearing mineral abundance
RF3, Saline
magnitude
RF4,
Aeolian
input
Communality
estimates
Na 0.12 - 0.96 - 0.94
Mg - -0.83 0.17 -0.12 0.73
Si - 0.95 - 0.22 0.95
K 0.91 0.34 - -0.13 0.97
Ca -0.17 -0.63 - -0.11 0.44
Ti 0.95 - 0.13 - 0.92
Mn 0.26 -0.79 - -0.14 0.72
Fe 0.99 - - -0.11 0.99
Cl - - 0.99 - 0.98
Cu 0.96 -0.17 - -0.13 0.98
Zn 0.97 -0.20 - -0.13 0.99
Ga 0.99 - - -0.12 0.99
Rb 0.98 - - -0.15 0.98
Zr -0.33 0.44 - 0.81 0.95
Hf -0.23 0.52 - 0.75 0.89
Th 0.98 -0.13 - -0.11 0.98
Standard
deviations
7.72 3.28 1.97 1.43 -
Variance proportion/%
0.48 0.21 0.12 0.09 -
Cumulative proportion/%
0.48 0.69 0.81 0.90 -
Blank represents those loadings which are under significant level in robust factor analysis. Communalities for each element are computed by
taking sum of the squared loadings, it can be referred to the length of the element arrows in loadings plot.
As a comparison to the aforementioned conventional factor analysis, RFA was performed to
reduce the systematic and random error of compositional data (according to Filzmoser, 2009;
Fig. 4-9C and 9D). Subsequently, the suitable and sensitive elements for further assessment of
sedimentological interpretations are compared. Element loadings (Tab. 4-4) and
communalities (cf., Figs. 4-9A and 9C) are thereby significantly higher compared with the
conventional method. Factors exhibiting eigenvalues >1 are extracted (e.g., five factors can be
determined by applying the Kaiser-Guttmann Criterion, Guttman, 1954). These factors have
variance higher than an input variable. Finally, the first four factors which are above the
parallel line are determined as confident factors (more details see Chapter 4.3.5; Franklin et
al., 1995). They represent ca. 90.00 % of the total geochemical variance of the XRF data set.
47
Relatively high (> 0.75, Tab. 4-4) positive or negative loadings of elements for each factor are
extracted. High loading elements for robust factor 1 (RF1) are Ti, Fe, K, Cu, Zn, Ga, Rb, Th.
RF2 has high loadings of Si, Mg, Mn. RF3 is represented by Na and Cl. RF4 yields high
loadings of Zr and Hf. All elements only display one relatively high loading, which implies
that they have only specific interpretation for one specific factor.
4.5. Discussion
4.5.1. Late Quaternary lithostratigraphy at the northern margin of the Ejina Basin
Similar late Quaternary lithostratigraphic facies are shared by five sections. Considering HC8,
aeolian phases dominated the sedimentary processes in U1 (beyond the upper limits of OSL
ages), which was sporadically interrupted by ephemeral riverine sediments.
Accompanied by several high salinity periods, the lacustrine sedimentation (U2) started
before 30 ka BP. The reported highest lake level of Sogo Nur occurred at around 41-33 ka BP
(i.e., MIS 3a, Lehmkuhl and Haselein, 2000; B. Yang et al., 2004 and literatures therein). The
highest shoreline of the Sogo Nur is radiocarbon dated to 33 ka BP (Wang et al., 2011). The
highest remnant beach bars near the Juyanze Basin was also radiocarbon dated to 37-29 ka BP
(Wünnemann et al., 2007; cf., Long and Shen, 2015). Molluscs from the highest shoreline of
eastern Juyanze Lake to the northwestern Badain Jaran Desert were dated to 30.40±0.87 ka
BP, indicating a huge expanded paleolake (Mischke et al., 2003). Additionally, δ18
O
reconstructions yielded high lake levels from 37-34, at 31 and 28-26 ka BP, respectively in
the Ejina Basin (Wünnemann and Hartmann, 2002). However, a far more eastern “Jilantai-
Hetao Megalake” existed between 50-60 ka BP (Chen et al., 2008a), the inception of the
lacustrine period occurred earlier compared with the stratum U2 in HC8. Furthermore, calcite
layers occur at depth of ca. 3.5 m within U2 (not captured in XRD data, Fig. 4-10). Cemented
calcareous layers in present time can be referred to an annual precipitation of 100-300 mm
(Hövermann, 1998), which indicates a much more humid period recoded by U2 compared to
today. In addition, the Sogo Nur lake basin experienced dune accumulation between 19-14 ka
BP (Lehmkuhl and Haselein, 2000), which is not observed here in section HC8. The
uppermost lacustrine sediments of U2 (Tab. 4-1; Fig. 4-3) yield calibrated 14
C ages of
13.661±0.227 and 28.757±0.500 ka BP, respectively.
48
Above U2, a mixture of fluvial / alluvial sand and gravels form a deflated gravel gobi surface.
Local ephemeral runoff occurred in U1 and the mixed fluvial sands and gravels may be
subsequently modulated by intensive deflation (cf., Nottebaum et al., 2015a).
4.5.2. Elemental characteristics of sediment archives
4.5.2.1. Elemental characteristics compared to granulometric composition
In order to properly interpret the geochemical behaviors of sediments, particular attention
should be contributed to elemental characteristics in relation to grain size parameters (Honda
and Shimizu, 1998), when assuming similar provenance. In case of absence of intensive
pedogenesis (see low Chemical Index of Alteration (CIA) in Fig. 4-6B), this heterogeneity
may originate in minerals’ re-distribution during transportation and deposition (Schettler et
al., 2009) and their deviant resistances to weathering processes (von Eynatten et al., 2012).
Most samples from U1 and U3 have higher proportions of coarse silt to sand. The clay
proportion is relatively low, indicating that the transport mode is high energy fluvial or
aeolian saltation, rather than a lacustrine or still water environment (Blott and Pye, 2012). The
clay and fine silt proportions can be considered as detrital component. Medium silt
contributes a considerable fraction to aeolian dust or loess deposits which are transported
several hundred meters above the surface, being trapped and deposited subsequently (e.g.,
Prins et al., 2007; Nottebaum et al., 2014, 2015b). Winter monsoon here is a low altitude
phenomenon (Vandenberghe, 2013) which may be a possible transporting mechanism. In
contrast, fine particles transported by Westerlies can reach up to 10,000 m (Sun et al., 2000;
Sun, 2004). Silty sand (Fig. 4-3) and fine sand proportions may indicate near surface
suspension and dust storm saltation occurring in winter and spring (Dietze et al., 2014). The
medium to coarse sand proportions may represent high energy transporting processes
(Derbyshire et al., 1998) exerted by the Hei River.
Previously, the grain size dependence of elemental (mineralogical) compositions of various
archives were tested and evaluated by a set of studies e.g., Honda and Shimizu (1998), Yang
et al. (2007), Schettler et al. (2009), Garzanti et al. (2009), Lupker et al., (2011) and von
Eynatten et al. (2003, 2012). However, few studies have investigated bulk geochemical of
granulometric proportions (cf., Fig. 4-5 and correlation matrix Fig. 4-8).
Median, mean, mode values are negatively correlated to alkali metals and ferromagnesian
elements e.g., Al, K, Ti, V, Fe, Ni, etc. In contrast, the positively correlated K and Si may
49
originate from orthoclase in sands (e.g., K-feldspar; Divis and McKenzie, 1975). Hf may
originate from weathering-resistant heavy minerals e.g., zircon, which are often enriched
during long aeolian or fluvial sediment recycling (cf., Owen, 1987). Thus, silica-rich minerals
(e.g., orthoclase) and allochthonous heavy minerals may be the main provenance for the
coarser materials in this endorheic basin. Ferromagnesian, mafic and mica source elements
encompassing Al, K, Ti, V, Fe, Ni, Cu, Zn, Ga Y, Nb, Nd, Pb and Th (cf., Nickel, 1954; von
Eynatten et al., 2012) are broadly correlated (+0.5-0.6) to clay and fine to coarse silt (Fig. 4-
8), S is only highly correlated to coarse silt (+0.5). Mg is only correlated to clay and fine silt
(+0.6 and +0.5, respectively). Ca and Sr are generally correlated to medium to coarse silt
proportions (cf., Fig. 4-8). Granitoid source elements e.g., K, As, Rb and V have negative
correlation with coarse silt. Interestingly, the heavy mineral sourced element Zr shows
slightly negative correlations with fine to medium sand (Fig. 4-8). von Eynatten et al. (2012)
reported the hump-shaped pattern of Zr (i.e., relatively low abundance in both clay and coarse
sand). In contrast, Zr has been suggested previously to be associated with coarse silt to sand in
aeolian sediments (e.g., loess) (Yang et al., 2006). Thus, whether Zr can be attributed to the
sand proportion needs to be tested in future studies. Furthermore, with similar geochemical
behavior as Zr, Hf is positively correlated to medium to coarse sand (Fig. 4-8). Arsenic and
Nd have no conspicuous correlations with any GSD fractions. This may be ascribed to their
diversified sources or presence in different minerals with different weathering resistances.
Silicon shows only intermediate correlation with medium sand (50 %). Being one of the
typical elements in all aeolian sand, clay minerals and some heavy minerals (Millot, 1970;
Pettijohn et al., 1973), Si cannot be easily applied as proxy for the coarse grain size
proportions.
4.5.2.2. Elemental characteristics of sediment archives
After deflation and disaggregation in the weak chemical weathering environment (Fig. 4-6B),
groups of minerals with similar physical and geochemical behaviors (e.g., durability) are more
likely to be enriched / depleted in specific archives or grain size fractions (von Eynatten et al.,
2012), in case no shifts of source rocks exist.
In the light of above statement, distinct enrichment / depletion of elements for certain archives
can be observed in this study: (i) Aeolian sands have higher contents of Zr, Hf, Ba and Si.
Aeolian sands transported in saltation mode during dust / sand storms have typical minerals of
quartz, feldspar, pyroxene and some heavy minerals (e.g., zircon; Fitzsimmons et al., 2009).
(ii) Lacustrine clay is composed of fine materials whose source minerals could be micas,
50
kaolinite, chlorite and some other ferromagnesian minerals (Hillier, 1993). They have a
common enrichment in K, Rb, Y, Ti, V, Nb, Fe, Cu, Zn, Al, Ga, Pb, As Th and Nd. Titanium,
Mg and Fe-bearing mafic minerals such as biotite are more often present in fine sediments
(Nesbitt and Young, 1996; Young and Nesbitt, 1998). (iii) Fluvial sands show high contents
in Mn, Mg, Cl and Na. This archive may contain more saline / evaporite minerals such as
mirabilite and glauberite formed after paleolake desiccation / saline processes (Smith and
Haines, 1964). (iv) Sandy loess has a distinctly high Sr content. Meanwhile, ferromagnesian
provenance elements e.g., Fe, Ni and V show relatively low values, which may be ascribed to
the lack of clay and fresh weathered materials in the archive. Generally, due to their similar
hydro-geochemical characteristics in pelagic and lacustrine settings, Sr behaves quite analog
as Ca (Calvert and Pedersen, 2007). Sr may engage together with Ca in carbonates in e.g.,
alkaline habitats. However, carbonates seems relatively rare in sandy loess (see low CaO and
MgO content in sandy loess (Tab. 4-3), and low aragonite and dolomite in Fig. 4-10), leading
to a distinctly different abundances between Sr and CaO (MgO). On the other hand, sandy
loess samples are corresponding to layers with spikes of quartz and feldspar concentrations in
the upper U2 (Figs. 4-4 and 4-10). And feldspar is more siliceous than most clay minerals
(Millot, 1970; Pettijohn et al., 1973). These set of evidences imply that the higher
concentration of quartz and feldspar may account for the higher Sr content (along with
relative high Si concentration) in the sandy loess. (v) The unsorted alluvial gravels have high
values of Ca, S, Cr, P and W. High content of P, S and W may result from the increasing
anthropogenic activities in the last thousand years (cf., northern Tibetan Plateau in Chen et al.,
2015). Naturally, Cr occurs in chromite together with Fe or Mg which is quite commonly
observed in nearby ultramafic intrusive rocks and ophiolite deposits (i.e., upper reach of Hei
River catchment in the western Qilian Mountains and the Bei Mountains, see Fig. 4-1 and Hu
et al., 2014). The generally high correlation between Cr and Fe, as well as Cr and Mg (Fig. 4-
8) demonstrate the chromite provenance transported not only as aeolian particles from the
west (acidic intrusive rock in Bei Mountains, Fig. 4-1) but also as fluvial material transported
by Hei River (greenschist-rich metamorphic rocks in mountain proximal reaches of the Hei
River, see Schimpf et al., 2014).
51
Fig. 4-10: Principle component scores, main mineral compositions and granulometric
properties of section HC8, RF1: weathering intensity, RF2: silicate-bearing mineral
abundance (different within lacustrine and aeolian phase), RF3: saline magnitude of
sediments, and RF4: quasi-constantly aeolian input. Lithologic patterns refer to Fig. 4-3.
Clay mineral group includes smectite, illite, kaolinite and chlorite. C, fSi, mSi, cSi, fS, mS and
cS denote the particle size of clay, fine silt, medium silt, coarse silt, fine sand, medium sand
and coarse sand, respectively.
Specifically, throughout the section HC8 and all other samples, Cl content is especially
elevated relative to Upper Crust Composition (UCC) values (Tab. 4-3), which may indicate
the generally high saline / evaporite mineral contents in late Quaternary sediments (cf., Smith
and Haines, 1964) of the dry endorheic Ejina Basin.
Furthermore, as illustrated in Fig. 4-9B and 9D, samples from the same sediment archive are
more likely to aggregate together in the score plot. Thus, multivariate statistics of
geochemical properties is a useful tool to discriminate the archive types. Outliers may be
attributed to certain subjectiveness in field discrimination of archive types and GSD
observations (Fig. 4-5).
4.5.3. Geochemical interpretation of sedimentary processes
As stated in Chapter 4.4.1, all sediments are dated to the (late) Quaternary. Although post-
depositional processes e.g., hydrodynamic sorting and diagenesis may indeed exert an
influence on the nature of geochemical compositions (Murray et al., 1992; Johnsson, 1993), in
case of late Quaternary sediments (cf., Mid- to Early-Cenozoic desert alluvium in Walker et
al., 1978 and Mesozoic sandstone and mudstone in Zhang et al., 2014b), the diagenesis
52
induced elemental alteration stays more likely in the initial stages (see Stage I in Walker et al.,
1978) and is therefore a negligible factor. On the other hand, the nature of parent rocks and
tectonic settings need to be clarified. As illustrated in the ternary A-CN-K diagram (Fig. 4-
6B), different archives exhibit generally a similar origin of mafic rocks which are close to the
CN apex (i.e., hornblende and clinopyroxene). Thus, markedly diversified terrain sources and
tectonic settings during the late Quaternary sedimentary processes can be ruled out.
Subsequently, elemental composition supplemented by XRD data from the key section HC8
can be employed to interpret the intriguing information of the sedimentary processes:
RF1 has relatively high loadings of felsic, ferromagnesian, mica and clay mineral source
elements such as Ti, Fe, K, Cu, Zn, Ga, Rb and Th (Tab. 4-4), which are all from soluble or
easily weathered minerals. These elements are commonly encompassed in clay minerals (cf.,
RF1 curve and clay mineral abundance in Fig. 4-10). Quartz is relatively stable and difficult
to decompose, while feldspars (mainly K-rich orthoclase, while Na- and Ca-rich plagioclase
are more likely to be attributed to RF2; Tab. 4-4) are more easily weathered to clay minerals
(Chen et al., 2010). Fine materials have high enrichment of least durable minerals, e.g., sheet
silicates such as micas (von Eynatten et al., 2012, cf. muscovite content in lacustrine clay and
alluvial gravels in Fig. 4-4). Hence, RF1 may indicate the varied weathering intensity, albeit
the magnitude is generally low throughout the sedimentary processes (cf., CIA in Fig. 4-10).
RF2 has high loadings of Si and negative loadings of Mg, Mn and Ca. The trend of RF2 is
generally anticorrelated (Tab. 4-4; Fig. 4-10) with dolomite / dolostone variances, which is
interpreted to precipitate within saline phase of playa basins (Last, 1990). Mg and Ca are
generally enriched together in carbonate and metamorphic silicate minerals such as
magnesite, dolomite, strontianite and pyroxene (Tucker et al., 1990). A possible origin may be
the autochthonous production of the carbonates within the lake period (IJmker et al., 2012b)
and allochthonous debris from aeolian sands (e.g., Ca in feldspathic sands, Divis and
McKenzie, 1975; cf. aeolian sands in Fig. 4) during a non-lacustrine phase. Mg was
particularly suggested as the most sensitive element to the paleolake depth (Shanahan et al.,
2013). Thus, tectosilicates (e.g., quartz and feldspar / orthoclase) are assumed to be the
predominant silicates in the aeolian U1, whereas clayey phyllosilicates (cf., RF1) e.g.,
kaolinite, illite and montmorillonite are assumed to be the prominent silicates in lacustrine
period U2 (cf., muscovite / illite content in lacustrine clay in Fig. 4-4). Hence, RF2 may
indicate still water level or in situ water budget (authigenic input) in lacustrine phases,
whereas with indication of silicate-bearing sands input during aeolian phases.
53
RF3 has high loadings of Cl and Na, which displays correlation with calcareous evaporate
minerals precipitated during the paleolake shrinkage (e.g., hydro-magnesite and halite, see
halite content in lacustrine clay (Fig. 4-4), cf. RF3 and halite pattern in Fig.4-10).
Furthermore, calcite can only be found in relatively high saline magnitude lacustrine periods,
albeit calcite determined in aeolian phases may be attributed to the mineral provenance
(intensive pedogenesis can be ruled here, see calcite and CIA in Fig. 4-10). Hence, RF3 can
be referred to the salinity component of sediments.
RF4 has generally high loadings of Zr and Hf, which are usually from dust / airborne minerals
e.g., quartz and feldspar (cf., aeolian sands in Tab. 4-3 and Chapter 4.5.2.2). Meanwhile,
factor scores do not show a pronounced downcore trend along section HC8, suggesting a
quasi-constant aeolian input into the basin systems throughout the late Quaternary.
In summary, the nature of bulk-compositions in the arid realm is governed by weak chemical
weathering, authigenic minerals and aeolian sand input. In contrast, concerning the suite of
late Quaternary sediments in this study, pedogenesis and diagenesis exert only very limited or
no influence. In addition, it needs to be noted that the generally undiversified source terrain
and tectonic settings during the sedimentary processes should be constrained as a prerequisite
before any following interpretations.
4.6. Conclusions
A practical strategy is presented to discriminate sediment archive properties and thereafter
sequence the controlling factors of sedimentary processes. The main conclusions are:
The considered records of northern Ejina Basin can be discriminated into three broad
lithological units: basal aeolian strata, lacustrine strata and the uppermost poorly-sorted
mixture of coarse sand and gravels.
Elemental characteristics in conjunction with the granulometric composition in different
sediment archives in the northern Ejina Basin are obtained. Aeolian sands have high contents
of Zr, Hf, Ba and Si. Especially Hf can be regarded as good indicator to discriminate the
coarse sand proportion. Sandy loess has high contents of Ca and Sr which both exhibit broad
correlations with medium to coarse silt proportions. Lacustrine clay has high contents of
felsic, ferromagnesian and mica source elements. Fluvial sands have distinctly high contents
of Mg, Cl and Na which are enriched in evaporate minerals. Alluvial gravels have especially
high contents of Cr which may originate from nearby Cr-rich bedrock.
54
Multivariate statistical methods applied to geochemical compositions is a useful tool to
discriminate archive types in our case. Considering the suite of late Quaternary sediments in
the arid realm, temporal variation of the bulk-geochemistry can be well explained by four
semi-quantified sediment components: (weak-) weathering intensity, silicate-bearing mineral
abundance, saline / alkaline influence of sediments, and the quasi-constant aeolian input into
the arid endorheic basin system. In contrast, pedogenesis and diagenesis exert only a limited
influence.
55
“It seems that these Heinrich events have left their
signature in the Chinese loess record. This is consistent
with simulations of the glacial climate, which imply that
the climates of the North Atlantic and China were linked
by the effect of westerly winds” (Stephen C. Porter and
Zhisheng An, 1995)
5. Lake sediments documented late Quaternary humid pulses in the Gobi Desert of
Mongolia: Vegetation, hydrologic and geomorphic implications
Kaifeng Yu 1, Frank Lehmkuhl
1, Frank Schlütz
2, Bernhard Diekmann
3, Steffen Mischke
4,
Jörg Grunert 5, Waheed Murad
6,7, Veit Nottebaum
1, Georg Stauch
1
1 Department of Geography, RWTH Aachen University, Templergraben 55, 52056 Aachen,
Germany
2 Lower Saxony Institute for Historical Coastal Research, Viktoriastraße 26/28, 26382
Wilhelmshaven, Germany
3 Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Telegrafenberg
A43, 14473 Potsdam, Germany
4 Faculty of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavík, Iceland
5 Department of Geography, Johannes Gutenberg-Universität Mainz, Becherweg 21, 55128
Mainz, Germany
6 Department of Palynology and Climate Dynamics, Georg-August-Universität Göttingen,
Untere Karspüle 2, 37073 Göttingen, Germany
7 Department of Botany, Kohat University of Science and Technology, 26000 Kohat, Pakistan
Considerable efforts have been devoted to decipher the late Quaternary moisture and thermal
evolution of arid central Asia. However, disparate interpretations still exist concerning
different proxies. The spatial and temporal heterogeneities have inhibited a holistic
understanding of general patterns and underlying mechanisms. To address these issues, two
parallel cores (ONW I, 6.00 m; ONW II, 13.35 m) were retrieved from lake Orog Nuur, in the
Gobi Desert of Mongolia. An array of multidisciplinary investigations of geomorphological
mapping, radiocarbon dating, geochemical and biotic studies embracing palynological and
56
ostracod valve analyses has enabled us to gain a comprehensive dataset for vegetation
development and hydrological variability over the last ~50 ka. Ample evidence reveals a
marked moisture pulse during the Marine Isotope Stage 3 (~36-~24 ka) which might have
induced the maximum last glacial expansion in the high elevated Khangai Mountains. A sharp
transition of Termination I (~11 ka) is indicated by geochemical, palynological, and ostracod
data. The lower area of the Orog Nuur catchment was dominated by Artemisia steppe in the
late Pleistocene and gradually altered to Chenopodiaceae desert steppe in the Holocene. The
early Holocene is also characterized by a relatively humid environment, albeit discordant
downcore variability of moisture and thermal signals can be derived between palynological
and bulk geochemical signals. The water body of the lake appears to be a distinct alkaline
environment during the Holocene which was subjected to frequent allogenic input and
disturbance of the anoxic states in relative to the late Pleistocene Epoch. These two humid
pulses may be the trait of a larger scale of arid central Asia that is documented in a suite of
archives. Considering kinetics, a coupled atmospheric component comprising both East Asian
Summer Monsoon and strengthened westerlies moisture supply seems to be the driving
mechanism. This coupled mode might have been modulated broadly by boreal insolation
variances. On the other hand, four harsh climatic conditions were documented in the core at
~47 ka, ~37 ka, the global Last Glacial Maximum and the Younger Dryas as playa phases. An
impeding of westerlies’ moisture conveying along with the retreated East Asian Summer
Monsoon might have contributed to these playa phases in the Gobi Desert of Mongolia.
5.1. Introduction
Being a fragile ecological system, environmental change in arid central Asia exerts
tremendous influence on a significant percentage of world population concerning nomadic
migration and alternation of political regimes (Pederson et al., 2014). The Gobi Desert in
southern Mongolia was recognized as one of the main dust sources for Chinese Loess Plateau
and pelagic sediments in the northwest Pacific (Pye and Zhou, 1989; Xiao et al., 1997; Lu and
Sun, 2000; Vandenberghe et al., 2006). Previously, general pattern of late Quaternary (in
particular Holocene) paleoclimate signatures of arid central Asia were defined and reviewed
by an array of works including Pachur and Wünnemann (1995), Yang et al. (2004, 2011),
Herzschuh (2006), Chen et al. (2008), An et al. (2008), Wang et al. (2010) as well as Wang
and Feng (2013). These compilations have suggested a distinct moisture regime of middle and
southern Mongolia in comparison to that of higher latitude Baikal catchments and East Asian
Summer Monsoon (EASM) domain of China (Yang et al., 2004; Wang and Feng, 2013).
57
Fig. 5-1: Location of the study area and paleoclimate records mentioned in the text (1, Kanas
Basin; 2, Darhad Basin; 3, Hovsgol Nuur; 4, Shaamar section; 5, Baikal Lake; 6, Kotokel
Lake; 7, Wulagai Lake; 8, Manas Lake; 9, Luanhaizi Lake; 10, Wuliangsu Lake; 11, Japan
Sea; 12, Lake Biwa; 13, Khangai Glacier; 14, Altai Glacier. More details refer to Tab. 5-3).
Panel A delineates schematic vegetation cover of Mongolia. Large-scale air mass controls
are marked with arrows, comprising East Asian Summer Monsoon (EASM), Indian Summer
Monsoon (ISM) and Westerlies. Ulaan Nuur (Lee et al., 2011, 2013) and Bayan Tohomin
Nuur (Felauer et al, 2012) are the only two reported lacustrine archives in the central to
southern Mongolia. Panel B exhibits north-south oriented topographic transect and
corresponding vegetation patterns. The eastern parts of Khangai Mountains (higher reach of
the Orog Nuur catchment) with altitudes between 3,500 m and 3,700 m a.s.l. have no modern
58
glaciers, while small ice-fields may reach down to 3,200 m a.s.l. in the western Khangai
Mountains (Lehmkuhl and Lang, 2001).
On the Mongolian Plateau and adjacent arid central Asia, continuous lacustrine sequences are
widely regarded as fundamental repository for paleoenvironmental signatures. A wealth of
works has been reported concerning the late Quaternary moisture and thermal history.
However, an array of paramount aspects still needs to be tackled. They are summarized as
follows: (i) biased or even contradictory conclusions may occur due to the interpretations of
different proxies. For instance, Schwanghart et al. (2009) advocated a warmer and wetter mid-
Holocene in Ugii Nuur (nuur = lake; in central-northern Mongolia) as inferred from the
mineral composition and bulk-geochemistry, while an arid mid-Holocene was reconstructed
from palynological studies (Wang and Feng, 2013). (ii) Most of the works poured attention
into the Holocene period, while only few records addressed the climate history during the
Pleistocene (Pachur and Wünnemann, 1995; Grunert et al., 2000; Lehmkuhl and Haselein,
2000). (iii) Substantial spatial heterogeneity is also noteworthy. An amount of studies on
lacustrine deposits were carried out in the Baikal area in Russia, in northern and western
Mongolia and in northern China (Fig. 5-1A; Tab. 5-2; Rhodes et al. 1996; Prokopenko et al.,
2001; Mischke et al., 2005; Hovsgol Drilling Project Members, 2009). Only two lacustrine
sequences were hitherto conducted in southern Mongolia, namely from the Bayan Tohomin
Nuur (Felauer et al., 2012) and the Ulaan Nuur (Lee et al., 2013) (Fig. 5-1A), albeit these two
records cover only the last ~15 ka. Furthermore, climate reconstructions might be biased by
uncertainties in the radiocarbon based age models due to lack of datable organic matter as
well as varying hard water effects (Mischke et al., 2013).
Consequently, it is indispensable to perform multidisciplinary studies on a critically selected
lacustrine sequence in attempting to gain a more unambiguous knowledge of the past
environmental changes. Here, two parallel cores (ONW I; ONW II) were recovered from the
western Orog Nuur Basin, in southern Mongolia. Based on previous investigations, a
multidisciplinary study involving sedimentology, bulk-geochemistry, palynology and
ostracod analyses were carried out, intending to:
(1) gain a compelling knowledge of moisture history in the Orog Nuur catchment over the last
~50 ka, and its governing atmospheric circulation;;
(2) elucidate the broad pattern of interrelated vegetation and hydrologic history of the Orog
Nuur catchment;
59
(3) generate and refine understandings on the spatial and temporal traits of moisture and
thermal signals in southern Mongolia, with aid of comparison with adjacent aeolian,
pelagic and mountainous glacial expansion records.
5.2. Study Area
The Orog Nuur catchment lies in the Valley of Gobi Lakes in southern Mongolia (Fig. 5-1A).
The Orog Nuur is a brackish habitat that is subjected to desiccation and it occasionally turns
into a playa environment. Tuyn Gol (gol = river) is the main inflow that originates from the
southern slopes of Khangai Mountains around 220 km north of the lake. The Orog Nuur has
no conspicuous outflow, resulting in a hydrologically closed basin system.
Fig. 5-2: Geomorphological map of the Orog Nuur Basin, three sets of lake beaches were
synthesized based on previous investigations. Section A1 is located at the third (highest) set of
sand ridge, more details see Chapter 5.5.2.2. General content is adapted after J. Grunert and
F. Lehmkuhl, and original cartography by T. Bartsch.
5.2.1. Geologic and geomorphic setting
The northwest-southeast orientated Valley of Gobi Lakes (ca. 1,400 to 1,800 m above sea
level, a.s.l.) is an elongated intramontane depression between the Siberian Craton and the
Tarim and Sino-Korean Cratons (Baljinnyam et al., 1993; Windley and Allen, 1993; Bardarch
et al., 2000; Cunningham, 2013). The Valley of Gobi Lakes is bounded by the Khangai
60
Mountains in the north and Gobi Altai Mountains in the south (Fig. 5-1B). The maximum
elevation of the Khangai Mountains is around 4,000 m a.s.l. at Otgon Tenger Uul in the west
(4,008 m a.s.l.; 47°36’30”N, 97°33’09”E) and ca. 3,000 m a.s.l. at Erhet Hayrhan Uul in the
east (3,037 m a.s.l.; 46°39’18”N, 101°13’56”E), whilst the summit of the Gobi Altai is in
3,957 m a.s.l. (Ikh Bogd Uul: 44°59’42”N, 100°13’51”E; uul = mountain). A left lateral
strike-slip fault is located at the southern side of the Khangai Mountains (Tapponnier et al.,
1979; Walker et al., 2007; Cunningham, 2013), while the southern part of the Orog Nuur
watershed exhibits the tectonic escarpment of the Gobi Altai and gently inclined alluvial fans
(Baljinnyam et al., 1993; Vassallo et al., 2011). The elongated forebergs of the Gobi Altai are
markedly faulted, warped and partially uplifted by thrust faults (Owen et al., 1997). As an
example, the 1957 earthquake (magnitude 8.3) caused a left-lateral displacement of 6 m and
vertical displacements approached 1.5 m (Baljinnyam et al., 1993), demonstrating that
tectonic movement may lead to some misinterpretations regarding shoreline ridges or terraces
(Fig. 5-2). Paleozoic volcanic and plutonic rocks are exposed in the basin and some places are
overlain by conglomerates. Previously, a much larger lake extents were reconstructed based
on three sets of shorelines (Lehmkuhl and Lang, 2001; Komatsu et al., 2001; Grunert et al.,
2009). These shorelines are situated 3 m, 10 m, 16 m (10 and 16 m = lake level 1, L.L.1) and
23 m (L.L.2) above the modern lake-level (Fig. 5-2). East-west oriented mobile dunes and
cuspate bars lie in the vicinity of the Orog Nuur (Stolz et al., 2012).
5.2.2. Climatic and vegetation setting
Mongolia is dominated by a continental climate characterized by dry and cold winter and a
precipitation maximum in summer (An et al., 2008). The mean annual precipitation along a
north-south transect ranges from ~500 mm to <100 mm (Fig. 5-1A). 65-75 % of the
precipitation occurs in summer due to the enhanced south-eastern cyclonic activity along the
polar front (Kostrova et al., 2014). Only ~100 mm precipitation is delivered in the lower Gobi
Desert of southern Mongolia, while the higher elevated Khangai Mountains can reach ~400
mm. According to records at Bayankhongor weather station near the Orog Nuur, the mean
July and January temperature in the Gobi Desert are ~16 °C and ~-20 °C, respectively, while
the mean annual temperature is about -2 °C to 5 °C (Felauer, 2012). In spring, dust- or
sandstorms frequently occur with maximum wind speeds exceeding 20 m/s (Hempelmann,
2010; Felauer, 2012). There is generally no snow cover because of the immense winter
dryness related to the predominant Siberian Anticyclone (Kostrova et al., 2014).
61
Fig. 5-3: Schematic lithologic column, photographs of sliced drilling core ONW II along with
the reference logs. Abbreviations: cl, clay; fsi, fine silt; msi, medium silt; csi, coarse silt; fs,
fine sand; ms, medium sand, cs, coarse sand. Mudstone or siltstone is represented in
schematic colors according to core description. In general, greyish calcareous clays (upper
fraction), siltstone and intercalated sandstones constitute the entire lacustrine sequence.
In general, the dominant soil types in central to southern Mongolia are dry-steppe
Kastanozems. Other common soil types are Chernozems/dark Kastanozems in the forest-
steppe zone as well as brown semi-desert soils (Tamura et al., 2012). The modern vegetation
follows a north-south transect from mountain taiga, forest steppe, grass steppe, desert steppe
62
and finally to desert communities (Fig. 5-1A; Hilbig, 1995; Gunin et al., 1999). Detailed
modern vegetation of the Valley of Gobi Lakes see Felauer (2011). In the forest steppes of the
Khangai and Altai Mountains, Larix sibirica is the dominating tree species on the northern
and eastern slopes, while steppe prevail the sun-exposed southern and western slopes (Miehe
et al., 2007). Pinus sibirica can be found in the restricted mountain taiga of the Khangai
Mountains (Hilbig, 1995). The uppermost boundary of the alpine meadows is ~2,900 m a.s.l.
(Lehmkuhl and Lang, 2001). Most of the lowland regions in the basin system are
characterized by open desert steppes and bare gobi surface. Dwarf bushes and reed-halophytes
are the dominant communities in the lower reaches of the Orog Nuur catchment (Murad,
2011).
5.2.3. Paleo- and modern glacial setting
As the depositional basin of Orog Nuur is linked to the higher Khangai Mountains via Tuyn
Gol, Quaternary glacial variance may play a pivotal role in terms of water supply and the
clastic delivery. In modern times, only the western Khangai has small ice caps and the
average equilibrium line altitude (ELA) was estimated in a range from 3,900 to 4,000 m a.s.l.
(Fig. 5-1B; Rother et al., 2014). The modern periglacial zone reaches down to 2,700 m a.s.l.
(Lehmkuhl and Lang, 2001). A set of Last Glacial Maximum (LGM) moraines at an altitude
of ~2,900 m. a.s.l. in the southern Khangai Mountains was dated thereafter to >21 ka
(Lehmkuhl and Lang, 2001). In addition, Ritz et al. (2006) determined ages of alluvial
sediments of the forelands of Gurvan Bogd (bogd = massif) by 10
Be cosmogenic nuclides
exposure dating and supposed an aggradation of sediments in the context of the global glacial
terminations. In the Gobi Altai, permafrost developed at ca. 22-15 ka and degraded since ~13
ka, and was thereafter diminished since the early Holocene (Owen et al., 1998).
5.3. Material and methods
5.3.1. Cores retrieval and sampling strategy
Two parallel sediment cores (ONW I: 6.00 m, 45°03’48”N, 100°34’39”E; ONW II: 13.35 m,
45°04’28”N, 100°35’08”E, 1,219 m a.s.l.) are retrieved from the western part of Orog Nuur
during the playa phase (Figs. 5-1A and 5-2). The core was opened, described and documented
in the field. Samples were separated and transported to University of Göttingen, Free
University of Berlin and the Alfred Wegener Institute in Bremerhaven for palynological,
ostracod, X-ray fluorescence and X-ray powder diffraction analyses. The remaining material
63
of the cores is preserved at RWTH Aachen University for grain size and TOC analysis. The
paleoenvironmental reconstruction is carried out primarily based on the longer core ONW II.
Table 5-1 The AMS 14
C ages were calibrated to calendar years with 2 σ standard deviation
using the CALIB rev. 7.1 (Stuiver et al., 1998) with the latest IntCal13.14c (Reimer et al.,
2013). According to the estimated real age based on the lithostratigraphy, raw radiocarbon
ages are subtracted by a reservoir effect of ~3,400±2,100 a BP before computing to
calibrated ages and generating the Bayesian age-depth model as given in Fig. 5-4.
Core
Nr.
Dept
h
(cm)
Lab Nr. Dating
material
14C ages
(a BP)
δ13C
(%)
2σ (cal a
BP)
(95.4 %)*
Estimated
real age
according to
lithostratigr
aphy
(cal a BP)*
Calibrated
Age based on
Bayesian age-
depth
modelling (cal
a BP)
Median Age
based on
Bayesian
age-depth
modelling
(cal a BP)
ONW
II
94 Erl-15622 Bulk
material
12,581±
103
-25.4 14,325-
15,192
- 5,054-16,854 10,697
ONW
II
199 Erl-15623 Bulk
material
13,242±
85
-24.2 15,691-
16,138
11,000-
13,000
5,988-17,523 11,499
ONW
II
271 Erl-15624 Bulk
material
17,733±
149
-25.4 21,042-
21,819
13,000-
18,000
10,905-22,893 17,703
ONW
II
392 Erl-15625 Bulk
material
17,713±
180
-24.5 20,945-
21,857
18,000-
19,000
10,827-22,924 17,046
ONW
II
571 Erl-15626 Bulk
material
19,738±
179
-23.8 23,344-
24,150
- 13,528-25,249 19,604
ONW
II
778 Erl-15627 Bulk
material
21,501±
217
-24.2 25,386-
26,122
- 15,408-27,018 21,685
ONW
II
1,19
2
Erl-15628 Bulk
material
46,103±
2,281
-25.4 44,908-
49,914
- 37,748-49,716 45,303
ONW
II
1,27
2
Erl-15629 Bulk
material
40,429±
1,340
-24.9 42,221-
46,226
- 34,226-47,355 40,873
ONW
I
386 Erl-12107 Bulk
material
16,020±
105
-28.1 19,049-
19,560
18,000-
19,000
- -
ONW
I
588 Erl-12108 Bulk
material
17,642±
112
-23.4 21,020-
21,653
- - -
* The reservoir effect is determined by taking average of the difference between the boldface ages in these two columns.
5.3.2. Lithology and chronology
In total ten radiocarbon ages were determined from bulk organic materials (Tab. 5-1) using
accelerator mass spectrometry (AMS) at the University of Erlangen-Nürnberg and
subsequently calibrated to calendar years using CALIB rev. 7.1 (Stuiver et al., 1998) with the
latest IntCal 13.14c calibration curve (Reimer et al., 2013). All radiocarbon ages are presented
as calibrated years (cal a BP) with a 2 σ error bar. The upper 24 cm of the core ONW II were
not retrieved. The R package “Bchron” (Parnell et al., 2008) was employed here to set up a
Bayesian age-depth model for core ONW II (Fig. 5-4) including its calibration using the
IntCal calibration curve mentioned above. Reservoir effects at different anchor points were
assessed by (i) identifying Termination I in bulk-geochemical and palynological sequences,
and (ii) comparing the Younger Dryas (YD) - related sand layer in Orog Nuur and Ulaan
64
Nuur (Fig. 5-1A; ~200 km northeast of Orog Nuur; Lee et al., 2011, 2013). All of the
radiocarbon ages were first subtracted by the reservoir effect and then computed to calibrated
calendar years and used in the establishment of the Bayesian age-depth model. Two
radiocarbon ages from core ONW I (386 cm, 588 cm) are employed to compare timing of the
stratigraphic units relative to ages of counterpart depths in core ONW II (Tab. 5-1; Fig. 5-4).
Fig. 5-4: Polylinear regression age-depth model of core ONW II generated from the
radiocarbon ages. Reservoir effect is corrected by (i) late Pleistocene / Holocene transition
(Termination I) as inferred from the suite of granulometric, palynological, ostracod and
geochemical studies (marked as black triangle), and (ii) the Younger Dryas related sand layer
(Ulaan Nuur, Lee et al., 2013). Frequency-dependent magnetic susceptibility (χFD), electrical
conductivity (EC), CaCO3, TOC and C/Natomic ratios of parallel core ONW I are employed to
cross-validate the age model of core ONW II. More details with respect to the
lithostratigraphy and chronological framework see text in Chapter 5.4.1.
5.3.3. Grain size analysis
Grain Size Distributions (GSD) of all samples with 5 cm intervals (114 samples for ONW I;
258 samples for ONW II) were measured using a Beckman Coulter LS13320 laser diffraction
particle size analyzer with a detection range of 0.04-2,000 µm. Preparation of samples follows
Konert and Vandenberghe (1997). Before measuring, a parallel test (HCl/H2O2- and H2O2-
only-treatment) was done to test the impact of possible incorporated calcium carbonate on the
65
resulting GSD, revealing however no pronounced differences (Schulte et al., 2016). Thus, all
measurements were performed uniformly without hydrochloric acid treatment. For clayey
sediments subsamples of 0.1 g and for coarse sands 1 g were utilized. 700 µl of 35 %
hydrogen peroxide was added to remove the organic components. Samples were then dried at
70 °C for two days. Sodium polyphosphate was added afterwards to avoid coagulation. The
Mie Theory was applied for GSD calculations (Özer et al., 2010; Schulte et al., 2016). The
final GSD represents the average of two subsamples, each of which was measured twice to
ensure reliability. In case notable offsets existed between subsamples, the measurement
procedure was repeated for the sample.
Fig. 5-5: Lithologic units of the core ONW II, and corresponding granulometric,
geochemical, and color variances. The grey bars depict the primary sand layers inferred from
the granulometric and lithostratigraphic characteristics of the core.
5.3.4. Electrical conductivity and magnetic susceptibility measurements
Electrical conductivity (EC, here equals specific conductivity) and magnetic susceptibility
(MS) were carried out exclusively on poweder sediment from core ONW I as an
environmental and salinity proxy. 50 ml water and 0.01 g KCl were added for each sample,
the EC with 10 cm interval (1 cm thick each subsample) was measured after 30 min using a
WTW LF 196 probe. MS at 1 cm interval was measured using a Barrington MS2 with a MS2
E sensor.
66
5.3.5. Carbon, nitrogen, sulfur, TOC and CaCO3 analyses
Carbon (TC), nitrogen (TN), sulfur (TS) concentrations, and the Total Organic Carbon (TOC)
content were determined, in order to gain a better understanding of the geochemical habitats
of the former water sediment interface. Samples were dried at 36 °C for 24 hours. The
samples in zinc capsules were subsequently analyzed in CHNS Analyzer EA3000. The
Scheibler gas method (DIN 19684) was employed to calculate the CaCO3 content, and 1-5 g
samples were utilized respectively. Calculation equation is as follows:
𝐶𝑎𝐶𝑂3 (%) = 𝑉 ∗ 𝑝 ∗ 0.1602/(𝑡 + 273) ∗ 𝐸 ∗ 𝐾
Where V is the volume of CO2 (cm3), p represents the atmospheric pressure (mm Hg), t
denotes room temperature (°C), E is the loss of weight (g) and K exhibits the correction factor
(here 2 is used). TOC was subsequently computed following Scheffer and Schachtschabel
(2002). The C/Natomic ratios throughout the ONW II core were computed and examined for
further interpretations (Meyers and Teranes, 2001).
5.3.6. X-ray fluorescence analysis, color analysis and multivariate statistics
The X-ray fluorescence (XRF) analysis was carried out in Alfred Wegner Institute (AWI) for
Polar and Marine Research in Bremerhaven, Germany, using an Avaatech XRF Core Scanner
configured with Canberra X-Pips 1500-1.5 detector (slit 10 mm, 10, 30 keV, 300 and 700
µA). The scanning interval is 1 cm, resulting in 1,335 measurements for the core ONW II.
Processes comprising subtracting a background curve, applying statistical corrections for
physical processes in the detector and deconvolution of overlapping peaks were performed
using scanner equipped WinAxil package (NIOZ and Avaatech, 2007). To gain a direct
knowledge about the depositional environment of former sediment-water interface, two
factors were computed based on the element dataset using factor analysis given in Yu et al.
(2016). Thereby, high loading elements for each factor in conjunction with the factor scores
provide intriguing insights into the sedimentary processes (Yu et al., 2016). In addition, X-ray
diffraction (XRD) for 14 samples at different depths was performed to assess the general
mineral composition and provide additional information for the interpretation of bulk
elemental compositions. The sediment color (RGB model) was scanned using a CCD line
scan camera.
67
Fig. 5-6: Diagram of analyzed taxa of pollen, fungal spores, aquatic algae and non-pollen
palynomorphs through the core ONW II plotted against the age and depth. All taxa were
aggregated into groups consist of arboreal plants (trees), shrubs, subshrubs/herbs/grasses,
aquatics, as well as coprophilous fungi and Glomus.
5.3.7. Palynology
In total 123 sediment subsamples of 1-2 cm3 were acquired in 5-10 cm intervals from core
ONW II and treated with KOH, HCl, HF and subsequent acetolysis for palynological analyses
(Erdtman, 1960; Moore et al., 1991). Lycopodium spores were added as exotic marker to
calculate pollen concentration (n/ml). With few exceptions, at least 400 pollen of terrestrial
plant were counted per sample. Pollen grains in clumps were counted separately (Schlütz and
Lehmkuhl, 2007). A total of about 50 pollen and 40 non-pollen palynomorphs (NPP: spores,
algae, etc.) were identified. Based on a variety of specific literatures (Müller, 1970; Vanky,
1994; Wang et al., 1995; Beug, 2004; Van Geel and Aptroot, 2006) and a collection of more
than 5,000 type slides, selected taxa and groups are arranged and presented in ecological
groups. All percentages of pollen and NPPs refer to the pollen sum of terrestrial plants. Beside
presented (Fig. 5-6), the tree taxa also comprise low abundances of Quercus, Ulmus, Tilia and
Alnus. The group of coprophilous fungi covers spore types related to the genera Arnium,
Cercophora, Delitschia, Podospora, Sordaria, Sporormiella, and Trichodelitschia. In
addition, the concentration of the pollen sum and of burnt plant particles (“charcoal”) as well
the ratio of Artemisia to Chenopodiaceae (A/C ratio) are given (see supplementary material).
The average of A/C ratio is marked by a line at 5.8 (Fig. 5-6). The pollen diagram was plotted
using the software C2 version 1.5 (Juggins, 2007) and was based on changes in taxa
68
abundance divided into 9 local pollen assemblage zone (LPZ), mostly in conformity with the
stratigraphic units.
5.3.8. Ostracod analysis
A total of 131 sub-samples from core ONW II were collected at 10 cm intervals for ostracod
analysis in order to examine and verify the paleohydrological conditions. The sediment was
treated with 3 % H2O2 for 48 hours and washed through 0.25 and 0.1 mm meshes. All
ostracod valves were picked from the dried sieved residues and identified according to Meisch
(2000) and Mischke and Zhang (2011). Further inferences are mainly based on Hiller (1972),
Hammer (1986), Meisch (2000) and Mischke et al. (2005).
5.4. Results
5.4.1. Bayesian chronology and lithostratigraphic units
According to the Bayesian age-depth model, the basal age of the core ONW II was
determined to be between 38 and 52 ka (Fig. 5-4). For lacustrine deposits in the Valley of
Gobi Lakes, lack of datable organic matter and old carbon effects may hamper the discerning
of reliable chronological framework. The Termination I has manifested remarkable
consistency in a complete set of palynological, geochemical and ostracod studies (i.e., abrupt
increase of pollen concentration, CaCO3 abundance, and ostracod valves, respectively after
the Termination I; Figs. 5-4, 5-5, 5-6 and 5-8) on core ONW II, and thereby validate the onset
of the Holocene stratigraphy in our age model. Thus, the sediments in a depth of ~205 cm are
presumed to be ~11,000 a BP old), which is ~4,600 years younger than that in our model. In
order to further corroborate the Termination I, Younger Dryas-related sand deposits in Ulaan
Nuur sediments dated by optically stimulated luminescence (OSL) is applied (Fig. 5-1A). The
chronology of the 600 cm Ulaan Nuur core was determined by 12 luminescence ages and the
sand layer regarding the Pleistocene and Holocene transition was determined to ca. 13-11 ka
(Fig. 5-4). Thereby, an age of 13,000 a BP could be assigned to sediments in ~248 cm depth,
which is ca. 3,500 years younger than that in the age model. In the light of Lee et al. (2011)
and Mischke et al. (2013), high reservoir effect in a scale of greater than 3,000 years in the
Orog Nuur sediments is highly feasible. Likewise, based on the estimation of the real ages of
the lithostratigraphy, the raw radiocarbon ages were subtracted by a reservoir effect of c.
3,400±2,100 yrs (Tab. 5-1) and then computed to calibrated calendar years and employed in
the establishment of the Bayesian age-depth model (Fig. 5-4).
69
Fig. 5-7: Scanning electron micrographs of ostracod valves derived from core ONW II
(external views). 1, juvenile Candona neglecta left valve (LV); 2-3, Leucocythere
dorsotuberosa, 2, female right valve (RV), 3, male LV; 4-11, Limnocythere inopinata, 4,
female LV, 5, female RV, 6, noded female LV, 7, noded female RV, 8, male LV, 9, male RV,
10, juvenile LV with spines along posteroventral margin, 11, juvenile RV with spines along
posteroventral margin; 12, juvenile Pseudocandona sp. LV; 13, Ilyocypris cf. inermis RV, 14,
Ilyocypris manasensis var. cornae LV, 15, Ilyocypris cf. bradyi LV.
Subsequently, based on lithostratigraphic, together with granulometric, and geochemical
characteristics, the entire sequence is delimited into nine units as follows (Fig. 5-3):
(1) Unit 1 (1,335-1,235 cm; ~50-~43 cal ka BP) is a greyish silty-clay layer with more than
50 % of silt and clay fraction. U1 is interbedded by a 20 cm (1,315-1,290 cm)
predominant coarse sand layer. CaCO3, C/Natomic along with TOC portray extremely low
values with respect to the sand layer and gradually increase upward (Fig. 5-5).
70
(2) Unit 2 (1,235-1,120 cm; ~43-~37 cal ka BP) is dominated by dark greyish clayey-silty
sediments (60-80 % of silt to clay proportion) with several intercalated brownish sand
layers (Figs. 5-3 and 5-4). CaCO3 retains roughly stable within U2, while C/Natomic ratio
manifests a more varied pattern, with values at gyttja-like laminae (~1,120 cm) greater
than 20 (Fig. 5-5). The C/Natomic ratios together with S content in rest depth of the unit
delineate generally low values.
(3) Unit 3 (1,120-1,057 cm; ~37-~35 cal ka BP) is a light greyish silty-clay stratum with
several intercalated brownish sand layers (Fig. 5-3). The C/Natomic ratios and TOC
progressively attenuate upcore and increase slightly in the uppermost U3. S and N
contents depict higher abundances than preceding units (Fig. 5-5).
(4) Unit 4 (1,057-660 cm; ~35-~24 cal ka BP) is a dark greyish silty-clay stratum with
intercalated sand layers at ~940 cm and ~840 cm, as well as several sinuously intercalated
layers with light greyish color (~750-730 cm). TC and CaCO3 concentration illustrate
relative low values with slight variability. Two vigorous spikes of TOC and C/Natomic ratio
occur at ~820 cm and ~720 cm (Fig. 5-5), albeit no counterpart phenomenon is manifested
in lithofacies and granulometric composition (Figs. 5-3 and 5-4).
(5) Unit 5 (660-390 cm; ~24-~19 cal ka BP) is a greyish silty-clay layer, which is intercalated
by sand layers at ~540 cm and ~460 cm (Fig. 5-3). Unlike U4, the TOC and C/Natomic
ratios represent quasi-constant values. In particular, the basal fraction of U5 is laminae of
dark brownish gyttja-like sediment characterized by pronounced high S and TOC content
(Fig. 5-5). Considering their counterpart stratigraphy in the core ONWI, spikes of
magnetic susceptibility (MS) in conjunction with slightly higher EC values in the
uppermost part of U5 are illustrated (Fig. 5-4).
(6) Unit 6 (390-350 cm; ~19-~18 cal ka BP) is a salient brownish coarse sand layer which is
also captured by the parallel core ONW I (Fig. 5-4). The sand fraction ranges from 91.5 %
to 96.1 %. CaCO3 abundance exhibits extremely low values whilst the C/Natomic ratios
illustrate high values with oscillations (Fig. 5-5).
(7) Unit 7 (350-248 cm; ~18-~13 cal ka BP) is a light greyish clayey-silty layer similar to U1.
The sand fraction ranges from 10 % to 35 % with an abrupt decrease in the basal part of
U7 to ~35 % and a subsequent decrease to 10 % at the depth of 283 cm. The CaCO3 and
C/Natomic ratio depict similar patterns as U1.
(8) Unit 8 (248-205 cm; ~13,000-~11,000 cal a BP) is dominated by the sand fraction (50-90
%). This sand layer is also documented in the parallel core ONW I and the adjacent Ulaan
Nuur (Fig. 5-1A). CaCO3 abundance remains analogue to U7, while the C/Natomic ratio
71
shows more fluctuations similar to the global LGM phase (U6). Throughout U8, S content
exhibits remarkable low values (Fig. 5-5).
(9) Unit 9 (205-25 cm; ~11-? cal ka BP) is marked by fine sediments comprising the highest
clay fractions (30-50 %) and the lowest sand proportion (1-10 %). An abrupt increase of
the CaCO3 (i.e., calcite, unpublished XRD data) and concomitantly diminished S content
are represented in U9. C/Natomic ratios decrease from ca. 20 to <10 upward and increase
incrementally approaching top of the core.
5.4.2. Bulk-geochemistry of the lacustrine sediments
Two factors were derived based on the multivariate analysis (Yu et al., 2016) on the bulk-
geochemistry of the lacustrine sequence. Factor 1 denotes high loadings of Fe, Mn and Al,
while factor 2 manifests particularly high loadings for Ca, Sr and Cl. Scores of each factor are
given in Fig. 5-9. Four concurrent periods exhibiting low values of factors 1 and 2 are
delineated in U1 (~1,300 cm), U2 (~1,120 cm), U6 (390-350 cm) and U8 (248-205 cm) (see
yellow bars in Fig. 5-9). In the Holocene (U9), factor 1 has extremely low values while factor
2 exhibits high values. Compared with the uppermost portion, the basal part of U9 represents
lower values for factor 1 and higher values for factor 2.
5.4.3. Palynological results
With values around 0.5 % tree pollen is infrequent throughout the whole archive and never
reaching more than 3.5 % (Fig. 5-6). Findings of Hippophae shrubs are more abundant for
most of the lower part at around 1.4 % (max. ca. 8 %) and Ephedra values exceed in the upper
part over 45 %. The genus Artemisia, includes several species of subshrubs and herbs, is
absolutely predominant with values around 70 % (max. 83.5 %). Chenopodiaceae are the
second common taxon. Their values are around 12 % but increase to 71.5 % when Artemisia
decreases at the top of the profile. For most of the profile the A/C ratio fluctuates between
0.13 and 14.5, but shows a clear trend to lower values and lower variability approaching the
top. Beside Artemisia and Chenopodiaceae only Poaceae occur in every of the 123 samples,
mostly with around 2.5 % and never but not reaching much more than 9 %. The pollen of
sedges (Cyperaceae) and some groups of Asteraceae (Matricaria-type, Liguliflorae) occurs in
about 120 samples respectively, while Rheum and Caryophyllaceae are represented in nearly
110 samples, Brassicaceae and the Senecio-type (Asteraceae) occur in around 100 samples. A
maximum of more than 10 % is reached only by the Cyperaceae and the Matricaria-type. The
pollen concentration is around 5,000 grains per ml (n/ml) but reaches up to greater than
72
41,000 n/ml in the upper part of the core (Fig. 5-6). In addition, nine local pollen zones
(LPZs) are mostly in conformity with the stratigraphic units delimited in Chapter 5.4.1 (Fig.
5-6). Pollen concentration (n/ml) and A/C ratios are employed to generally constrain semi-
quantified thermal (T) and effective moisture (M) anomalies (Fig. 9; Ma et al., 2008, 2013;
Yang and Scuderi, 2010; Zhao et al., 2012).
5.4.3.1. Unit 1 (LPZ 1; 1,335-1,235 cm; ~50-~43 cal ka BP)
Artemisia dominates with pollen percentages at around 70 %, while Chenopodiaceae stay
below 10 %. The A/C ratio increases, while percentages of spores (coprophilous fungi,
Glomus-type) and aquatics (Botryococcus, Pediastrum) are low.
Fig. 5-8: Absolute abundances of determined ostracod species, number of taxa and number of
valves plotted against lithologic units.
73
5.4.3.2. Unit 2 (LPZ 2; 1,235-1,120 cm; ~43-~37 cal ka BP)
Chenopodiaceae increase to 30 %, Artemisia falls below 50% and the A/C ratio to 1.6. Values
of spores and most aquatics increase considerably in the second half.
5.4.3.3. Unit 3 (LPZ 3; 1,120-1,057 cm; ~37-~35 cal ka BP)
Values of Artemisia are around 70 %, Chenopodiaceae are below 20 %. Spores stay quite
common, while some green algae (Botryococcus) and rotifer resting eggs (cf. Trichocerca
cylindrica) decrease considerably. Other green algae (Pediastrum) remain on a low level and
the amount of mandibles of Chironomidae is from now on recurrent over 1 %.
5.4.3.4. Unit 4 (LPZ 4; 1,057-660 cm; ~35-~24 cal ka BP)
In general, the abundance of Artemisia increases slightly reaching values around 80 % while
percentages of Chenopodiaceae decrease weakly, leading to some high A/C ratios in the
middle of LPZ 4 (including the maximum A/C ratio of 14.5 through the core). After a short
suspend the before sporadic finds of Salix pollen become more frequent. Aquatics like rotifer
resting eggs (55 %) and Pediastrum (43 %) reach their absolute maxima before the middle of
LPZ 4 and decrease substantially thereafter. In addition, only the upper boundary of the LPZ 4
shows slightly different depth compared with that of the Unit 4 in lithostratigraphy (Figs. 5-2
and 5-6). To provide a consistent outline in the following discussions, time slices of the
lithostratigraphic units are employed given that there is no unambiguous boundary taxa-
marker through those depths.
5.4.3.5. Unit 5 (LPZ 5; 660-390 cm; ~24-~19 cal ka BP)
Percentages of Artemisia are reduced around the middle of LPZ 5 while Chenopodiaceae
values increase and therefore the A/C ratio falls to values below 4. Finds of green algae
(Botryococcus, Pediastrum) and rotifer resting eggs (cf. T. cylindrica) strongly reduce or even
disappear around the turn to LPZ 5. Short after spore values are reduced as well. The
continuous finds of Chironomidae since LPZ 3 expires abruptly at the end of LPZ 5 for the
rest of the record. The pollen grain concentration increases to values of greater than 8,000
n/ml and up to 17,000 n/ml short before the end of LPZ 5.
74
5.4.3.6. Unit 6 (LPZ 6; 390-350 cm; ~19-~18 cal ka BP)
In Fig. 5-6, the LPZ 6 is represented by a single sample (372 cm) of low pollen concentration
(400 n/ml) and a low pollen sum of 200 grains instead of more than 400 in the samples below
and above. Due to insufficient pollen content, two further analyzed samples are not plotted.
The amount of Hippophae pollen seems to be quite high in and around LPZ 6 and the low
values of cf. T. cylindrica and Pediastrum continue the trend from the end of LPZ 5.
5.4.3.7. Unit 7 (LPZ 7; 350-248 cm; ~18-~13 cal ka BP)
With values of some 10,000 n/ml, the pollen concentration is not only much higher than in
LPZ 6 but even considerable higher than in LPZ 5. While the curves of Artemisia and
Hippophae decline towards the end of LPZ 7 and the curve of Salix gets disrupted, pollen of
Ephedra, including the E. distachya-type and the E. fragilis-type, increases for the first time
to above 5 %. The A/C ratio drops markedly at the top of LPZ 7 below its mean level (5.8)
and coprophilous fungi vanish for nearly the rest of the record. Botryococcus and Pediastrum,
after reaching high values again, nearly disappear at the end of LPZ 7.
5.4.3.8. Unit 8 (LPZ 8; 248-205 cm; ~13-~11 cal ka BP)
The pollen concentration is reduced and Artemisia and Hippophae drop to their lowest values
till then while Chenopodiaceae pollen becomes much more common. The A/C ratio falls
sharply to lowest values (0.4-1.7) so far and Ephedra increases for the first time to over 30 %.
Algae and resting eggs are present in small numbers. Pollen of the Sparganium-type, here
locally named Typha angustifolia/australis, increases drastically to its highest amounts (max.
13 %), while it occurred only very sporadically in the preceding record.
5.4.3.9. Unit 9 (LPZ 9; 205-25 cm; ~11-? cal ka BP)
After a sharp rise the Artemisia curve falls again and Chenopodiaceae become dominant
resulting in A/C ratios <1 and <0.4 lastly. While the record of Hippophae ends with the onset
of the LPZ 9, Ephedra curve reaches its highest values. Tribulus terrestris, sporadically till
then, exhibits a more closed curve in LPZ 9, but never exceeds 1.5 %. Finds of the Juniper-
type occur for the first time, but only very sporadically. After a strong increase, Botryococcus
finds disappear. T. angustifolia/australis values decrease considerably and remain below 3 %.
75
Furthermore, a salient increase of the pollen concentration from some 5,000 n/ml to >41,000
n/ml occurs at the onset of LPZ 9 (Fig. 5-6).
5.4.4. Ostracod species and valve abundances
Valves of eight ostracod species were identified from the sediments of core ONW II:
Limnocythere inopinata (unnoded valves of female and male specimens, and noded female
specimens), Ilyocypris cf. bradyi, Ilyocypris cf. inermis, Ilyocypris manasensis var. cornae,
Sarscypridopsis aculeata, Pseudocandona cf. compressa, Candona neglecta and
Leucocythere dorsotuberosa (female and male valves) (Fig. 5-7). A total of nine samples did
not contain any ostracod valves. The maximum abundance of 380 valves per sample is
recorded at 187 cm. Valves of L. inopinata represent the dominant taxon throughout the core.
The other taxa are only sporadically recorded (Fig. 5-8):
(1) Unit 1 (1,335-1,235 cm; ~50-~43 cal ka BP): L. inopinata is the predominant species in
U1. The number of valves displays an increasing tendency upcore and approaches 142 at
1,244 cm. Two carapaces of L. inopinata are preserved at 1,284 cm.
(2) Unit 2 (1,235-1,120 cm; ~43-~37 cal ka BP): The ostracods exhibit minimum valve
number at 1,158 cm (5) and a maximum at 1,124 cm (157). Eight carapaces of L.
inopinata are recorded at ~1,190 cm.
(3) Unit 3 (1,120-1,057 cm; ~37-~35 cal ka BP): U3 is marked by an incipient increase of the
valve number (generally >150). One to sixteen valves of I. cf. inermis are recorded at the
upper part of U3 (1,074-1,057 cm).
(4) Unit 4 (1,057-660 cm; ~35-~24 cal ka BP): A significantly high valve number (309) is
achieved in the basal part of U4 (1,034 cm). Specifically, C. neglecta and L.
dorsotuberosa occur at 877-827 cm (Fig. 5-8). One valve of I. cf. bradyi appears at 794
cm and one valve of I. cf. inermis is represented at 683 cm.
(5) Unit 5 (660-390 cm; ~24-~19 cal ka BP): Two carapaces of L. inopinata were recorded in
the basal part of U5 (653 cm). a high valve number (312) was recorded at 415 cm. This
layer is overlain by sediments with I. cf. bradyi at 407 cm.
(6) Unit 6 (390-350 cm; ~19-~18 cal ka BP): U6 is marked by a low abundance of valves.
One valve of I. cf. inermis is preserved at 373 cm. L. inopinata has vanished throughout
this unit.
(7) Unit 7 (350-248 cm; ~18-~13 cal ka BP): L. inopinata is recovered from the very
beginning of U7, albeit the valve number remains relatively low. One valve of I. cf.
inermis occurs at 285 cm and 257 cm, respectively.
76
(8) Unit 8 (248-205 cm; ~13-~11 cal ka BP): U8 is marked by frequent appearance of I. cf.
bradyi at 227-207 cm. A suite of species comprising I. manasensis var. cornae, S.
aculeata and P. cf. compressa are represented for the first time in core at 207 cm.
(9) Unit 9 (205-25 cm; ~11-? cal ka BP): U9 is characterized by a transient increase of total
taxa of ostracod as well as the number of valves (Fig. 5-8). The valve number per sample
reaches its maximum (380) of the core at 187 cm. I. cf. bradyi and I. manasensis var.
cornae are preserved at 202 cm. In the uppermost part of the core (31 cm), three valves of
I. cf. bradyi are represented.
5.5. Discussion
5.5.1. Vegetation dynamics and hydrologic history of the Orog Nuur
Biomes and corresponding environmental conditions can be derived from palynofacies (Figs.
5-6 and 5-9; e.g., Tarasov et al., 2011). However, beside the ostracod fauna (Fig. 5-8), in
terms of direct hydrological signals of the lacustrine sediments, bulk-geochemical fingerprints
would be a vital indicator:
(1) For the high loading elements of factor 1 (i.e., Fe, Mn and Al), aluminosilicates and micas
in clayey sediments were recognized as the main host (Millot, 1970). Considering the
behavior of Mn in the pelagic realm, insoluble oxi-hydroxides (Mn3+
and Mn4+
) are
represented in oxygenated environments, while soluble Mn2+
occurs in anaerobic
environments (Calvert and Pedersen, 2007). In terms of higher lake level i.e.,
suboxic/anoxic water bottoms, more soluble Mn will be readily engaged into carbonate
lattices and thereby will share analogue variance pattern as CaO or CaCO3, which seems
largely untenable in this study (Ca has high loading for factor 2). This is consistent with
the C/Natomic ratios of the bulk material, those values greater than 20 can be ascribed to the
frequent input of allochthonous materials (Fig. 5-5; Meyers and Lallier-Vergès, 1999). In
summary, factor 1 may point to the redox state of the depositional environment, from
which higher scores indicate reduced environments.
(2) Those elements for factor 2 (i.e., Ca, Sr and Cl) are always associated with carbonates
(Tucker and Wright, 1990). The analogue pattern between calcite and the CaCO3 along
with the absence of the dolomite and aragonite (unpublished XRD data) indicate that the
carbonates in the Orog Nuur are mostly presented as calcite. As suggested by Wünnemann
et al. (2010), calcite is practically authigenic precipitation in the lacustrine environment.
In addition, Yu et al. (2016) suggest that the aeolian activity hasn’t been significantly
77
altered. This is also demonstrated by the largely unchanged quartz and K-feldspar contents
determined by the XRD (see Chapter 6, and Fig. 6-3). Hence, factor 2 may indicate the
downcore variability of the authigenic productivity.
Based on the entire dataset, a comprehensive view of vegetation dynamics, hydrologic history
and climate developments are provided as follows:
5.5.1.1. Unit 1 (~50-~43 cal ka BP): relatively humid Artemisia steppe around a shallow
lake
As the amount of tree pollen is low and dominated by wind pollinated taxa, the wider area
around the Orog Nuur was most likely treeless. Shrubs of sea buckthorn (Hippophae) were
quite common and most probably growing on unconsolidated sand and gravels along the Tuyn
Gol and other inflows and/or the Orog Nuur shore. The buckthorn may have been
accompanied by some willows (Salix). Dry minerogenic habitats carried xeromorphic shrubs
of Ephedra and Nitraria.
As for most of the late Pleistocene, steppes were the dominating vegetation type during Unit
1. They were very rich in Artemisia, accompanied by some Chenopodiaceae. Regarding to
their potential high pollen representation due to wind transport, grasses (Poaceae, Cyperaceae)
must have been quiet sparse while insect pollinated herbs like different kinds of Asteraceae
(Liguliflorae, Matricaria-type, Senecio-type) and others (Rheum, Caryophyllaceae,
Brassicaceae) must have been more common than the grasses.
The small amounts of green algae (Botryococcus, Pediastrum), rotifer resting eggs (cf. T.
cylindrica) and chironomid mandibles (Chironomidae) suggest a lake environment. The
monospecific occurrence of L. inopinata in the lowermost unit and samples without ostracod
valves indicate a fluctuating and possibly temporary water body (Meisch, 2000; cf., grey
horizontal bars in Fig. 5-5). Increasing valve numbers from the base to the top of the unit
suggest a gradually increasing stability of the water body.
78
Fig. 5-9: Semi-quantified thermal, moisture and hydrogeochemical history as inferred from
the palynological and geochemical studies. Palynological indices (curves a and b) are
inferred from pollen concentration and Artemisia/Chenopodiaceae ratios, respectively, whilst
the geochemical indices (curves c and d) i.e., factor scores, are entrained from multivariate
statistics based on the bulk-geochemistry of the sediments (Yu et al., 2016). Fossil pollen
concentration is linked to the thermal anomalies (e.g., Conroy et al., 2009). Considering the
authigenic productivity, the Holocene may experience a distinct lacustrine phase with higher
content of calcite and carbonates. In this study, the vertical blue bars depict humid pulses,
while yellow bars denote the playa phase inferred from the granulometric and
lithostratigraphic characteristics of the core. Furthermore, as stated in Chapter 5.4.3, the
pollen assemblages preserved in the lacustrine archive may indicate merely local vegetation
signals surrounding the lower catchment of the Orog Nuur. Therefore, inconsistency between
the reconstructed effective moisture and lake level fluctuations may occur. Northern
hemisphere temperature (e): Johnsen et al. (2001), H events: Bond et al. (1993), 45 °N
summer insolation (f): Whitlock and Bartlein (1997), west subtropical pacific SST (g) and sea
level changes (h): Tudhope et al. (2001). In addition, the MIS 3/MIS 2 transition in this study
is some 24 cal ka BP, which is largely in agreement with that in Martinson et al. (1987).
5.5.1.2. Unit 2 (~43-~37 cal ka BP): relatively dry and fluctuating Artemisia steppe and
water surplus to the lake
Regarding the decreasing and strongly fluctuating Artemisia curve, the overall climatic
conditions in Unit 2 were unstable. While increases in Poaceae and Asteraceae indicate more
humid pulses, a higher abundances of Chenopodiaceae point to dryer or locally more salty
79
conditions. The increase of aquatics hints at a more stable water body of the lake. The
synchronously increase of spores of coprophilous fungi and spores of the Glomus-type
document a higher water inflow, as those fungi spores are mostly transported into lakes by
water (Ahlborn et al. 2015; Shumilovskikh et al. 2016).
The ostracod assemblage in Unit 2 is similar to those of Unit 1 apart from the general
occurrence of L. inopinata valves in all samples. Slightly more stable conditions are
suggested. Although it may be preserved in the catchment at any time in the past, the
occurrence of carapaces of L. inopinata probably results from temporarily high sediment
accumulation rates due to the sporadic delivery of large amounts of sediment during flood
events. The higher water income as documented by aquatics, fungi spores and ostracods may
indicate melt-water impulses either from the Khangai via the Tuyn Gol or by smaller streams
from the neighboring Gobi Altai. A playa phase during the upper U2 (~37 ka) is also
documented by oxidizing environment and low authigenic productivity (Fig. 5-9).
5.5.1.3. Unit 3 (~37-~35 cal ka BP): relatively dry Artemisia steppe and lake stabilization
Artemisia-steppes are again the prevailing vegetation type. Fungi spores still indicate ongoing
water inflow into the Orog Nuur. From now on, chironomids (Insecta: Diptera) became well
established in the lake for most of the late Pleistocene, possibly indicating slightly less
brackish conditions (Chen, 2009). As the A/C ratios during Unit 3 and in the prevailing time
of Unit 2 are low, the river discharge documented by the fungi spores might be more
generated by precipitation in the higher elevations of the catchment/pastures (Khangai, Gobi
Altai) than in the low lands surrounding the lake.
L. inopinata reaches higher abundances in Unit 3, indicating a more stable environment
and/or possibly a lower sediment accumulation rate. The portion of male valves of L.
inopinata increases towards the top of the unit. More alkaline conditions were apparently
established following a period with more Cl- or SO4-dominated lake waters (see Chapter 6,
and Fig. 6-2). Higher runoff to the lake might have probably caused a dilution of the more
saline lake waters, which is also indicated by the occurrence of I. cf. inermis near the top of
Unit 3. The species typically prefers spring habitats and waters flowing from springs (Victor
and Fernando, 1981; Meisch, 2000; Mischke et al., 2005). Springs are situated today at the
southern shore of the Orog Nuur fed by water from the flanking Gobi Altai.
80
Fig. 5-10: Synthesis and comparison of paleoenvironmental variability in Mongolia and
adjacent regions since the Marine Isotope Stage 3 as developed in this study and other
selected records from literatures: 1, Kanas Glacial (Xu et al., 2009; Zhao et al., 2013); 2,
Manas Lake (Rhodes et al., 1996); 3, Darhad Glacial (Gillespie et al., 2008); 4, Hovsgol
Nuur (Murakami et al., 2010); 5, Luanhaizi Lake core LH2 (Mischke et al., 2005b); 6, Baikal
Lake (Williams et al., 1997; Prokopenko et al., 2001); 7, Kotokel Lake (Shichi et al., 2009); 8,
Retreat of southern boundary of the Gobi Desert (Feng et al., 2007); 9, Shaamar Section (Ma
et al., 2013); 10, Wuliangsu Lake (Selvaraj et al., 2012); 11, Wulagai Lake (Yu et al., 2014);
12, Biwa Lake (Xiao et al., 1997); 13, Japan Sea (Nagashima et al., 2007); 14, Dust model in
central Asian desert (Nilson and Lehmkuhl, 2001). Here, the vertical blue bars depict humid
pulses, while yellow bars denote the playa phase inferred from the granulometric and
81
lithostratigraphic characteristics of the core. Calibrated radiocarbon ages were labeled as
black triangles near the bottom axis. Climate intervals including the Younger Dryas (YD) and
Last Glacial Maximum (LGM) were demarcated near the uppermost axis. More details
concerning the proxies of each archive refer to Tab. 5-2 and locations refer to Fig. 5-1A.
5.5.1.4. Unit 4 (~35-~24 cal ka BP): relatively humid Artemisia steppe and transition
from maximum high to quite low lake levels
Higher A/C ratios point to somewhat less arid conditions in the landscape around. With regard
to the spores, the water inflow into the lake underwent no substantial changes. In the first half
of Unit 4 extremely high frequencies of rotifer eggs and Pediastrum point to an amelioration
of living conditions for water organisms. This might especially include much less brackish
conditions implying a fresh to oligohaline Orog Nuur of greater water depth (Jiang et al.,
2006, Zhao et al., 2007; Kramer et al., 2010). I. cf. inermis is present at the base of the unit,
suggesting substantial inflows and lower salinity levels (Victor and Fernando, 1981; Meisch,
2000; Mischke et al., 2005). The mostly monospecific ostracod assemblage and low valve
abundance afterwards indicates a return to less stable lake conditions and a higher salinity.
The few shells of C. neglecta and L. dorsotuberosa recorded at ca. 28 ka (Fig. 5-8) were
possibly washed to the lake from neighboring habitats during floods or may represent a few
species living at the extreme ends of their tolerance ranges.
The Orog Nuur experienced a higher lake level and somewhat fresh water conditions in the
beginning of Unit 3 (~ 35 ka) until about 30 ka BP. This MIS 3 lake high stand seems to be a
characteristic for arid central Asia as well as the Tibetan Plateau (Feng et al., 2007), albeit
debate still exists as the ages may be biased as determined by different chronological methods
(Lai et al., 2014; Long and Shen, 2015), which is out of the scope of this study. As the A/C
ratios point to a relatively humid landscape, the effective moisture must have increased in
general, possibly by lower temperatures documented in the altitudinal down move of the
landscape belts (Fig. 5-11; e.g., Lehmkuhl and Haselein, 2000).
5.5.1.5. Unit 5 (~24-~19 cal ka BP): Artemisia steppe and playa to shallow lake
While the A/C ratios indicate relative humid conditions, fungi spores point to lasting river
water inflow, nevertheless low and respectively interrupted evidences of the aquatics hint at a
deterioration of the lake environment in the beginning of Unit 5. Probably glaciers as water
resource have diminished by the end of the prevailing Unit 4. The maximum peak of the
82
Glomus-type might document short-lived run-off events with fast soil erosion but overall low
water surplus. Subsequent algae and rotifers were quite common again while chironomids
seem to diminish during Unit 5 before they disappear permanently. Chironomids
disappearance and the synchronous reduction of rotifers and Pediastrum may result from
changes in the salinity. Slightly higher valve abundances in Unit 5 indicate a diminished
sediment accumulation rate and/or slightly more stable environmental conditions. Lower
abundances of male valves of L. inopinata closer to the top of Unit 5 probably result from an
increase in salinity and predominance of Cl- or SO4-dominated lake waters.
5.5.1.6. Unit 6 (~19-~18 cal ka BP): Artemisia steppe and sand accumulation
From three pollen samples in Unit 6 only one (372 cm) yielded a minimum of palynological
remains. The overall low pollen concentration coincides with sand accumulation in the lake.
The relatively abundant pollen of Rheum might came with the sand by strong winds into the
playa basin, as Rheum nanum and most other rhubarbs of Mongolia grow in desert habitats,
from where sand is blown out (Hilbig, 1995; Grubov, 2001). As chironomids are eliminated
and demanding aquatics (rotifers, Pediastrum) are low, the water quality and amount may
have been limited, possibly caused by a decreasing inflow (low fungi spores). The almost
monospecific occurrence of L. inopinata, lowest valve numbers and low numbers of male
valves of L. inopinata suggest unstable conditions and Cl- or SO4-dominated, relatively saline
lake waters.
5.5.1.7. Unit 7 (~18-~13 cal ka BP): Artemisia steppe, higher lake level and decreasing
river influence
The landscape was still dominated by Artemisia steppes. Some amelioration of the lake
ecosystem is indicated by higher Pediastrum abundance, while the stay away repopulation by
chironomids point to quite salty conditions. One could speculate that an inhospitable brackish
water body was seasonally overlaid by light fresh water, making a blooming of Pediastrum
possible. At the end of Unit 7 the decrease of Hippophae and Salix together with the offset of
coprophilous spores marks a strong decrease in river discharge into the western basin of the
Orog Nuur. The contemporaneous increase in Chenopodiaceae and Ephedra indicates the end
of Artemisia steppe dominance. The ostracod assemblage of Unit 7 is almost identical to those
of Unit 6 and conditions apparently remained similar. A few valves of I. cf. inermis in the
upper part of the unit probably result from sporadic flood events.
83
5.5.1.8. Unit 8 (~13-~11 cal ka BP): Establishment of deserts around a strongly shrinking
lake
Unit 8 stands for the displacement of Artemisia steppe by desert communities. The spreading
of Chenopodiaceae reflect the desiccation of the wider landscape possibly including the
establishment of salt tolerant Chenopodiaceae species on the salty playa enclosing the
shrinking Orog Nuur. Ephedra includes typical desert species, which are less salt tolerant and
often inhabit places with strong physical weathering like rocks and pebbles (Grubov, 2001;
Schlütz and Lehmkuhl, 2007). The desertification of the landscape came together with low
river influence (Hippophae, Salix, Glomus-type) leading to a nearly disappearing of algae and
rotifers. The sudden spreading of T. angustifolia and/or T. australis - two highly salt tolerant
cattails - and the only representatives of the Sparganium-type at the Orog Nuur (Hilbig, 1995)
indicate marshlands near the core site. The occurrences of valves of I. cf. bradyi, I.
manasensis var. cornea, S. aculeata and P. cf. compressa in the upper part of Unit 8 indicate a
decreasing salinity in the lake and apparently wetter conditions. Recorded valves of I. cf.
bradyi and S. aculeata suggest that flowing waters entered a relatively brackish lake. I. cf.
bradyi is known as typical stream dweller whilst S. aculeata prefers slightly brackish
(oligohaline to mesohaline) stagnant waters (Ganning, 1971; Meisch, 2000; Mischke et al.,
2005). In summary, the YD event correlated phase is marked by a playa to shallow swamp
habitat, influenced by sporadic pulses of fluvial inputs. This is corroborated by the low values
of redox and authigenic productivity (Fig. 5-9).
5.5.1.9. Unit 9 (~11-? cal ka BP): desert steppe and a shallow lake of high salinity and
alkalinity
The abruptly increased pollen concentration (Fig. 5-9) points to overall higher plant
productivity. This may be associated to the improved climatic conditions and mark the
inception of the Holocene period (Fig. 5-9; e.g., Mackay et al., 2012). Likewise, this is in
concordance with the somewhat higher occurrence of trees probably indicating more effective
moisture in higher elevations. While birches (Betula) may have grown in the nearby Gobi
Altai, where small relicts of Betula exist today (Fig. 5-11), pollen of conifers (Pinus, Picea,
Abies) comes most probably from remote mountain areas (e.g., Ma et al., 2008). Artemisia-
steppes recovered in the beginning, indicating higher effective moisture, but did not become
dominating again. As documented by Chenopodiaceae and Ephedra, the lower elevations
stayed arid. The reestablished steppe may have allowed a higher density of wild and/or
domestic animals, leading to an increasing grazing pressure in the dry habitats documented by
84
the expansion of the ectozoochorous grazing weed T. terrestris (Miehe et al. 2007). In
addition, Juniper shrubs (Juniperus-type) might have been favored by grazing (Miehe et al.
2009). In terms of ostracod records, the I. cf. bradyi and I. manasensis var. cornea occur only
in the lowermost part of Unit 9, indicating relatively low salinities and higher runoff to the
lake. Afterwards, the almost monospecific ostracod assemblage of L. inopinata valves, the
absence of male valves of the species and a few samples lacking ostracod valves indicate
harsh fluctuating environmental conditions and the establishment of generally Cl- or SO4-
dominated, relatively saline lake. In the modern context, note that the Tuyn Gol flows into the
eastern main basin of the Orog Nuur until today, the offset of the Hippophae and Glomus-type
finds may indicate the establishment of the recently active sediment barrier, segmenting the
small western basin including the coring sites from the direct influence of the Tuyn Gol.
Today the water in the western basin comes in addition from springs, located at the margin as
well as inside the basin, and with a small creek fed by the precipitation in the Gobi Altai. To
the end, our archive documents a strong decrease and the expansion of Chenopodiaceae
deserts, the still today predominating vegetation (Fig. 5-1B).
Likewise, in the perspective of bulk-geochemistry, sediments exhibit particularly high
authigenic productivity in the early Holocene and slightly decreased afterwards (Fig. 5-9).
The higher authigenic productivity is characterized by high abundance of Ca and Sr in the
sediments. The Holocene water body is presumably an alkaline habitat with higher
concentrations of cations that can be bound to chloride. However, this high alkalinity or
salinity in the water body may not necessarily result from high temperatures. As illustrated in
Fig. 5-9, the reconstructed thermal condition of the Holocene appears to be slightly better than
that during the MIS 3. This mild temperature typically favors the flourishing of Betula in
northeastern Asia biomes (Fig. 5-6; Heusser, 1989). Hence, rather than temperature, a
significant change of the sediment provenance might have contributed to the distinctive saline
and alkaline environment in the Holocene, albeit assessment of the provenance change is out
of the scope of this study. On the other hand, the supply of the meltwater may provide
abruptly increased riverine inflows into the sedimentary basin and thereby destroy the former
established suboxic habitats, and invoke low values of redox conditions through the Holocene
(Fig. 5-9). In summary, the relatively higher lake level in the early Holocene might be
explained by climate-induced higher meltwater flux from ice, snow and frozen ground in the
higher catchment, and subsequent drying till today as a result of diminishing inflow and
higher evaporations.
85
Tab. 5-3: Synthesis of lacustrine, pelagic, aeolian and glacial sequences (spanning at least
the MIS 3) in the vicinity of the Gobi Desert. For locations of each site refer to Fig. 5-1A.
Nr. Name Archive a
Lat.
(°N)
Long.
(°E)
Chronology b
Time
span
Analytical
techniques
and proxies c
Reference
1 Kanas
Basin
G 48°41’ 87°01’ OSL 0-50
ka
M Xu et al. (2009); Zhao
et al. (2013)
2 Darhad
Basin
G 51.3° 99.5° 14C, CRN 0-150
ka
ELAs, sh Gillespie et al., (2008)
3 Hovsgol
Nuur
L 51°53’ 100°21’ 14C 0-27
ka
ICP-MS,
AAS, TOC
Fedotov et al. (2008);
Hovsgol Drilling
Project Members
(2009); Murakami et al.
(2010)
4 Shaamar
Section
A 50.2° 105.2° 14C 0-35
ka
p, ms, gs,
CaCO3
Feng et al. (2007); Ma
et al. (2013)
5 Baikal
Lake
L 52°32’ 106°12’ 14C, mag 0-75
ka
d, BSi, Prokopenko et al.
(2001)
6 Kotokel
Lake
L 52°45’ 108°05’ 14C 0-50
ka
p, ch, BSi Shichi et al. (2009)
7 Wulagai
Lake
L 45°25’ 117°29’ 14C 0-48.5
ka
loi, gs Yu et al. (2014)
8 Manas
Lake
L 45°45’ 86°00’ 14C 0-37.8
ka
p, d, XRD,
δ13C, 18O
Rhodes et al. (1996)
9 Luanhaizi
Lake
L 37°35’ 101°12’ 14C, TIMS 0-50
ka
os, ICP-AES,
thmag
Mischke et al. (2005)
10 Wuliangsu
Lake
L 40°58’ 108°54’ 14C 0-36.5
ka
ms, gs, XRF,
CaCO3
Selvaraj et al. (2012)
11 Japan Sea O 37°04’ 134°42’ 14C 0-
144.4
ka
ESR, CI, ms Nagashima et al. (2007)
12 Biwa Lake L 35°15’ 136°01’ tephro 0-145
ka
EQF, SEM, gs Xiao et al. (1997)
13 Khangai
Glacier
G 46°-48° 96°-103° CRN 0-45
ka
M Rother et al. (2014);
Lehmkuhl et al. (2015)
14 Altai
Glacier
G 46°-52° 82°-95° - 0-
>132
ka
ELAs Lehmkuhl et al. (2011)
Notes:
a Archives: L, lacustrine; G, paleoglacial; A, aeolian loess and interbedded paleosol; O, oceanic material.
b Chronology methods: mag, paleomagnetic events/reversals; OSL, optical stimulated luminescence dating;
IRSL, infrared-stimulated luminescence dating; CRN, beryllium-10 cosmogenic nuclide dating; TIMS, thermal
ionisation mass spectrometry.
c Analytical techniques and proxies: d, diatom abundance; BSi, biogenic silica content; loi, loss on ignition; gs,
grain size distribution; p, pollen spectra; m, glacial moraines; ch, charcoal; os, ostracod; thmag, thermomagnetic
measurements to check the Curie Temperature of each sample; XRF, X-ray fluorescence analysis; XRD, X-ray
diffraction analysis; ms, mass magnetic susceptibility; AAS, atomic absorption spectrometry; ICP-MS,
inductively coupled plasma mass spectrometer; ICP-AES, inductively coupled plasma atomic emission
spectroscopy. ELAs, equilibrium-line altitudes; sh, paleolake shoreline; SEM, scanning electron microscopic
photographs; TOC, total organic carbon; ESR, electron spin resonance; CI, crystallinity of quartz; EQF, aeolian
quartz flux.
86
Notably, the palynofacies (i.e., local pollen zones/LPZs in Chapter 5.4.3) employed here may
only reveal the vegetation evolution in the lower catchment surrounding the lake. Direct
hydrologic signatures could merely be referred from algae, ostracod specimens and bulk-
geochemical characteristics of the lacustrine sediments. Hence, not surprisingly, geochemical
and palynological indices may occasionally result in inconsistent or controversial
interpretations regarding the past environmental changes (Fig. 5-9). This specious mismatch
between palynological and geochemical signals may be attributed to a nonlinear response of
the catchment biomes to the orbital scale insolation modulations (Schwanghart et al., 2009;
Wang and Feng, 2013). For instance, in the Holocene, high temperature induced higher
evapouration may reduce the annual moisture and thereby the A/C ratios. However, the
thermal characteristics may exert only limited impacts on lakes levels and accompanied
geochemical nature of the core sediments. A holistic view of different proxies as well as
geomorphological features is therefore indispensable in attempts to reconcile the
inconsistency, and interpret sound and reliable paleoenvironments. On the other hand, in
contrary to the multiproxy reconstruction for the hydrological/moisture conditions, credible
paleo-thermal reconstruction in the lacustrine or terrestrial realm still awaits novel techniques.
The testified functions as given in Ma et al. (2008, 2013) seem not applicable in this study due
to lack of pivotal taxa. Apart from the palynomorph- (Fig. 5-9), chironomid-, and diatom-
based reconstructions, pilot studies on (i) fluid inclusions (Lowenstein and Brennan, 2001)
and (ii) organic signatures of branched glycerol dialkyl glycerol tetraethers (brGDGTs;
Tierney et al., 2010) preserved in lacustrine sequences would be practical and promising in
achieving sound thermal signals, albeit the following discussions have focused more on
moisture signals in terms of the broadly arid condition in the Gobi Desert of Mongolia.
5.5.2. Geomorphic evidence of the past environmental change in the Orog Nuur
catchment
In the scenario of Orog Nuur catchment, past glacial moraines in the higher elevated Khangai
Mountains and shorelines of the Orog Nuur in lower catchment area (Figs 5-1 and 5-2) are
pivotal aid that could be employed in paleoenvironmental reconstructions.
5.5.2.1. Glacial advances in the higher reaches of the Orog Nuur catchment
Glaciology and permafrost study is an essential complement to gain a more comprehensive
knowledge of the past environment in the higher reach of Orog Nuur catchment (Fig. 5-1B).
In the Khangai Mountains (above 3,000 m a.s.l.), as determined by the cosmogenic nuclide
87
dating of the terminal moraine boulders (Lehmkuhl et al., 2016), the oldest detected glacial
advance was dated in the westernmost part of the Khangai to ~40 ka, which roughly
corresponds to the uppermost of U2 (Fig. 5-11). Thus, in the western Khangai Mountains, ca.
40 ka marked the inception of the glacial advance in MIS 3. In addition, two granite erratic
boulders (47.85°N, 97.31°E; 47.68°N, 97.21°E) from terminal moraines of Otgon Tenger in
the western Khangai were dated using 10
Be/26
Al exposure dating, yielding an age of 30.5±1.4
ka and 37±2.7 ka (Lehmkuhl et al., 2016). Moreover, the MIS 3 glacial advances were also
suggested in (i) western Khangai (Rother et al., 2014), (ii) Chinese Altai (Xu et al., 2009;
Zhao et al., 2013), and in (iii) Darhad Basin (Fig. 5-1A; Gillespie et al., 2008), implying that
these MIS 3 glacial advances may be a common phenomenon in a greater spatial scale in the
arid central Asia. Interestingly, the glacial expansion during the MIS 3 interstadial is even
larger than that during the LGM (Rother et al., 2014), albeit the MIS 3 is a relatively warm
interstadial (Dansgaard et al., 1993). During the MIS 3, the time span of the glacial advance is
in phase with the lacustrine period in this study, whereas the LGM and YD glacial advances
are accompanied by playa phases as inferred from the core and the accumulation of dune
sediments in the adjacent sections of the Orog Nuur (Section A1 in Fig. 5-2; Figs. 5-10 and 5-
11). For the Khangai Mountains and adjacent regions, a suite of the compilations from
Lehmkuhl et al. (2011, 2016) and Rother et al. (2014) have implied that nival and periglacial
features together with major glacial expansions occurred between 28 and 24 ka, and thereafter
a dry and cold phase (24-15 ka) accompanied by loess accumulations is inferred.
Consequently, the considerable humid pulse during the mid- to late-MIS 3 (~36-~24 ka as in
this study) may be the main driving mechanism for MIS 3 glacial advance, whereas it is not
pertained in case of the paucity of moisture in the LGM, when lower temperature in particular
in the high elevated eastern Khangai Mountains would have been the main forcing factor
(Rother et al., 2014; Lehmkuhl et al., 2016). On the other hand, no glacial advance was
detected in the higher eastern Khangai Mountains, where merely patches of undated
periglacial remains were observed (Fig. 5-11), which may be attributed to the unfavored
thermal amelioration and hence the elevated ELA since the early Holocene. In southern
mountain ranges (i.e., Gobi Altai) of the Orog Nuur, the degradation of permafrost since
Termination I was concluded by Owen et al. (1998), which coincides with the fewer
occurrences of periglacial features on the southern slopes of eastern Khangai Mountains (Fig.
5-11).
88
5.5.2.2. Ancient shorelines of the Orog Nuur
Although it might be slightly altered by neotectonic events, evidences of former sand beaches
of the Orog Nuur can still shed light on the paleohydrologic conditions of the lake. The oldest
remnants of beach sediments can be found 57-62 m above the present lake-level (L.L.3).
Section A1 (Fig. 5-2; 45°11’N, 100°46’E) provides two luminescence ages, namely HDS 047
and HDS 049 (at depth of ~0.5 m and ~3 m, respectively; Lehmkuhl and Lang, 2001). The
age of ~70 ka (HDS 047: 75±14 ka; HDS 049: 71±11 ka) serves as evidence for the highest
former lake level (L.L.3, 1280 m a.s.l.). Hence, the highest beach ridges may indicate high
lake levels in the early part of the last glacial or even the Eemian period, and these phases are
also supported by floodplain sediments in the Mongol Els (300 km west of the Orog Nuur;
Stolz et al., 2012). Consequently, the reconstructed MIS 3 lake level may be slightly lower
than the early last glacial paleolake. Considering the lower sand ridges in Fig. 5-2, recessional
beach lines reveal that the shrinking of the lake can be identified at 20 m (L.L.2), 10-16 m
(L.L.1) and 3 m above the modern lake-level. The L.L.2 and L.L.1 may be indicative of a
more or less stable lake corresponding to MIS 3 and early Holocene humid pulses,
respectively, albeit no detailed chronology is available here. Moreover, in the study of
Komatsu et al. (2001), based on the remote sensing investigations of the paleoshorelines in
the catchment and nearby basins, the stable paleolakes were estimated at MIS 3. In addition,
in the Valley of Gobi Lakes, Owen et al. (1997) suggest that more humid conditions have
prevailed between 40 and 23 ka. On the southern slopes of the eastern Khangai Mountains, as
concluded by Lehmkuhl and Lang (2001), high humidity-induced slope processes such as
sheet wash was stronger in the early Holocene.
5.5.3. Regional synthesis - humid pulses inferred from different archives in the vicinity
of the Gobi Desert
In the Orog Nuur, two chief humid pulses (~36-~24 ka, ~11-~? ka) and four relatively short
playa phases (~47 ka, ~37 ka, ~19 ka and ~13-~11 ka) were determined (Figs 5-9, 5-10 and 5-
11). Several more thin coarse-grained sediment layers can be identified through the MIS 3
humid pulses, they are however less significant as aforementioned playa phases (Fig. 5-5).
Furthermore, rather than pure aeolian sediments, this layers might be attributed to fluvial
materials as determined by geochemical compositions (see Chapter 6.5.2.4, and Fig. 6-3),
albeit their granolometric composition share similar chracteristics with aeolian sands (Yu et
al., 2016). In order to gain a holistic paleoenvironmental view in a greater spatial scale, an
array of studies in the proximity to the Gobi Desert is compiled and evaluated (Fig. 5-10).
89
5.5.3.1. Marine Isotope Stage 3
Humid conditions during the middle and late MIS 3 were recorded in northern Chinese
deserts and northern Mongolia by several works based on diverse archives and proxies
(Herzschuh, 2006; Yang et al., 2011). As illustrated in Fig. 5-10, the higher moisture signals
along with glacial advances during mid- to late MIS 3 are documented in the Kanas Basin (Xu
et al., 2009; Zhao et al., 2013), Manas Lake (Rhodes et al., 2006), Darhad Basin (Gillespie et
al., 2008), Wuliangsu Lake (Selvaraj et al., 2012), Wulagai Lake (Yu et al., 2014), Biwa Lake
(Xiao et al., 1997) and Shaamar loess section (Feng et al., 2007; Ma et al., 2013). This entire
set of records hints at a humid pulse during the MIS 3 in arid northern China and northwest
Pacific (Tab. 5-2; Figs. 5-1 and 5-10). Considering other records in Tengger Desert and
drylands of northern China, most of the high lake-level periods have also been dated to the
main interstadial of the last glaciation i.e., MIS 3 (Pachur and Wünnemann, 1995; Lehmkuhl
and Haselein, 2000), albeit age difference may occur as determined by different chronological
methods (Lai et al., 2014; Long and Shen, 2015). More specifically, a higher lake level at
Gaxun Nur was determined to 41-33 ka (Fig. 5-1A; Wünnemann and Pachur, 1998).
Likewise, a marked expansion of needle-leaved forest in the southern Mongolian Plateau and
northern China in the late MIS 3 were suggested by several studies (Pachur and Wünnemann,
1995; Ma et al., 2013). This MIS 3 humid pulse is also corroborated by low dust supply as
suggested by the model of Nilson and Lehmkuhl (2001) and in the northwest Pacific (Leinen,
1989) (Fig. 5-10). However, whether the high lake levels of Qinghai Lake have to be assigned
to MIS 3 or MIS 5 still remains elusive (Colman et al., 2007; Madsen et al., 2008; Liu et al.,
2010).
On the other hand, in the Baikal catchments and northern Mongolia, Baikal core GC-1
(Williams et al., 1997; Prokopenko et al., 2001), Kotokel Lake (Shichi et al., 2009) and
Hovsgol Nuur (Murakami et al., 2010), no humid pulses during the MIS 3 is displayed,
suggesting a distinct moisture pattern compared with those in northern China and northwest
Pacific (Fig. 5-10).
In summary, aquatic organisms such as Pediastrum and Botryococcus, as well as relative
haigh A/C ratios have revealed a humid pulse during the MIS 3 (Fig. 5-6; Unit 4 in the core
sequence), albeit this phase is not well presented in other plynological and geochemical
fingerprints (Fig. 5-9). Although there exist certain inconsistency between all this suites of
imprints, we need to focus on the direct signals such as aquatic organisms in order to better
discern the hydrological state of the Orog Nuur in the past.
90
5.5.3.2. Marine Isotope Stage 2
A fluctuating shallow lake together with a moisture deficit in the LGM and YD were implied
in the studies of Manas Lake (Rhodes et al., 1996), Luanhaizi Lake (Mischke et al., 2005),
Wuliangsu Lake (Selvaraj et al., 2012), Wulagai Lake (Yu et al., 2014), Biwa Lake (Xiao et
al., 1997) and Schaamar loess section (Feng et al., 2007; Ma et al., 2013) (Fig. 5-10). Arid
LGM conditions were previously suggested for the Asian interior by numerous works (Lu and
Sun, 2000; Bush, 2004). After the LGM, a stepwise climate amelioration was conceived by
Herzschuh (2006) as such can be correlated to U7 in our study (Fig. 5-9). Interestingly, the
reconstructed authigenic productivity curve (Fig. 5-9) exhibit broadly similar downcore
variability as west Subtropical sea surface temperature (SST) and sea level variances
(Tudhope et al., 2001), indicating certain links between the moisture supply in the Gobi
Desert and the northwest Pacific, both of which lie beneath the pathways of the boreal
westerlies and EASM throughout the late Quaternary period (Nagashima et al., 2007).
5.5.3.3. The Holocene
As illustrated by geochemical indices (Fig. 5-9), the higher effective moisture and authigenic
productivity in the early Holocene corroborates the lake expansion phase postulated in
Lehmkuhl and Lang (2001). This is also in line with a suite of studies in Luanhaizi Lake
(Mischke et al., 2005), Baahr Nuur (Feng et al., 2005), Khyaraany loess-paleosol sequence
(Feng, 2001), Qilian Mountain loess sequences (Nottebaum et al., 2015), Yili loess-paleosol
sequence (Li et al., 2011) and other westerlies domain signals (Arz et al., 2003; Ilyashuk and
Ilyashuk, 2007), albeit Herzschuh (2006) synthesized the palynologcal signals in this area and
conceived that the early Holocene optimum may not be a uniform phenomenon in the entire
westerlies domain. However, as reconstructed by palynofacies (Fig. 5-9), the increasing
temperature and decreasing moisture in the early Holocene is concordant with the Altai region
(Demske et al., 2005; Rudaya et al., 2009). To gain a broad view, a wealth of palynological
studies with focus on Mongolia was carried out by Tarasov et al. (2000, 2007), assembling the
vegetation history of Mongolia and Baikal catchment and reconstructing a broadly warm and
humid early Holocene and a deteriorated climate since the mid-Holocene. Likewise, Miehe et
al. (2007) investigated forest patches in the Gobi Altai and concluded a shift from dark taiga
to a steppe environment over the last 5 ka. In the Holocene, the greatest dust fluxes from Asia
into the northwest Pacific are estimated to be in the mid-Holocene (Leinen, 1989). A dry mid-
Holocene mega-thermal that may favor dust storms was also evidenced in studies in Inner
Mongolia (Chen et al., 2003). Moreover, late Holocene dune sediments were uncovered in the
91
sections around the Orog Nuur catchments during our field investigations (Fig. 5-2),
indicating a less favored environment after the mid-Holocene and in modern times. However,
due to the absence of at least the late Holocene sediments (the uppermost 24 cm of core ONW
II), interpretations for this time slice in our study are restricted.
In addition, as aforemented, the high temperature induced higher evapouration might have
reduced the annual moisture in the catchment, shifted the vegetation to desert steppe (e.g., the
increses in Ephedra, Chenopodiaceae, and Nitraria; see supplementary materials) and thereby
reduced the A/C ratios in the Holocene (Yang et al., 2010; Zhao et al., 2012). However, the
thermal characteristics may exert only limited impacts on lakes levels and accompanied
geochemical nature (higher contents of carbonate) of the core sediments (Fig. 5-9).
5.5.4. Potential driving mechanisms for the late glacial climate change in the Gobi Desert
From an arid central Asia perspective, the moisture signature is of particular importance with
respect to the dust activity in the Asian interior as well as for the northwest Pacific (Duce et
al., 1980; Leinen, 1989; Pye and Zhou, 1989; Nakai et al., 1993; Nilson and Lehmkuhl, 2001;
Nagashima et al., 2007). A general assertion is that the moisture signatures here have an out-
of-phase relationship with the EASM domain (Chen et al., 2008). At least in the western part
of arid central Asia, the moisture signal is believed to be brought by the westerlies
(Vandenberghe et al., 2006; Chen et al., 2008). Nonetheless, recently, based on the analysis of
modern precipitation signals, Huang et al. (2015) demonstrated that the Gobi Desert of
southern Mongolia is outside of the core region of westerlies-dominated arid central Asia (50-
90 °E, 36-54 °N). In their study, the southern Mongolian Plateau portrays a modern
precipitation variation pattern analogue to the EASM-influenced China, while an anti-
correlated relationship is obtained in contrast to the core region of the westerlies (50-90 °E,
36-54 °N). The early Holocene moisture optimum is at odds with the dry pattern in the
westerlies-dominated Hovsgol Nuur (Fig. 5-1; Prokopenko et al., 2007; Rudaya et al., 2009).
On the other hand, the reconstructed indices (Fig. 5-9) imply intimate connections between
hydrochemical conditions of the Orog Nuur and the west subtropical Pacific signals. Hence,
partially contrary to the envisaged assertion, it is likely that thermal and moisture signals in
the Gobi Desert may not be driven by unitary mechanisms. In other words, the Gobi Desert is
rather affected by an atmospheric mode comprising both the EASM and the westerlies, which
as a dynamically coupled system, is governed by the nature of boreal insolation variances
(Fig. 5-9).
92
Fig. 5-11: Synoptic compilation of hydrologic, vegetation and geomorphic history of the Orog
Nuur catchment over the last ~50 ka. Playa & dune phase is recovered from the
granulometric and lithostratigraphic characteristics of the core ONW II. More details see
Chapter 5.5.1. Glacial advance in Khangai Mountains refer to Rother et al. (2014) and
Lehmkuhl et al. (2016). As mentioned in Chapter 5.5.3.3, in the Holocene, the high
termpertature induced higher evapouration might have triggered lower annual moisture in
the catchment (see A/C ratios in Fig. 5-9), it has however less impacts on the better
hydrological condition of the water body as revealed by higher authigenic productivity (Fig.
5-9) in the more alkaline water column (see Chapter 6.5.2.2, and Fig. 6-6).
5.5.4.1. Humid pulses in the Gobi Desert
The asynchronous Holocene optimum of East Asia was demonstrated by An et al. (2000),
Kerr (2003) and Chen et al. (2008), concluding that the moisture from the northwest Pacific
can be transported into continental Asia. On the other hand, the westerlies were also
suggested as a feasible moisture supplier. For instance, a weakening of the Siberian winter
anticyclone coupled with a retreat of the northern hemisphere ice sheet would have acted as a
93
forcing factor that permits more moisture to penetrate into the Asian interior by both Atlantic
cyclone activity and the EASM (cf., Moros et al., 2004; Peltier and Fairbanks, 2006). Boyle
and Keigwin (1987) reported the connection between the north Atlantic thermohaline
circulation - namely Atlantic meridional overturning circulation (AMOC) - and temperature in
high-latitude regions. In the scale of the last glacial period, the massive iceberg discharges
may trigger global scale climate change via alteration of the AMOC (Bond et al., 1993;
Broecker, 1994; Porter and An, 1995; Böhm et al., 2015). The prominent decay of ice sheets
and concomitant weakening or shutdown of AMOC (Ding et al., 1995) were demonstrated to
be the conceivable driving mechanism for the global scale transition during the last
deglaciation (Rodwell et al., 1999; Rahmstorf, 2002; Liu et al., 2009; Clark et al., 2012).
Furthermore, the moisture history of the north Atlantic may exert fundamental impacts on the
EASM signals via the teleconnected interactions (Ivanova, 2009). In this study, the higher
lake level in the MIS 3 and early Holocene implies a broadly resembling pattern with the
higher values of 45°N summer insolation (Fig. 5-9; Whitlock and Bartlein, 1997). Likewise,
further western Altai depicts a similar and only slightly lagged pattern compared with the
boreal insolation curve (Eichler et al., 2009). Interestingly, this early Holocene optimum is
also documented in the Indian Monsoon domain (Sirocko et al., 1993; Fleitmann et al., 2003;
Gupta et al., 2003; Liu, 2011), leading to our assumption that, the Gobi Desert is governed by
a coupled Asian monsoon system that is largely modulated by boreal insolation variances.
Presumably, in the mid-latitudes, higher insolation forcing during the MIS 3 and early
Holocene has supplied more moisture into the Asian interior via pathways of EASM or
westerlies (Cheng et al., 2016).
5.5.4.2. Playa phases in the Gobi Desert
Considering the aridity of the Asian interior, Bush (2004) suggests that the arid conditions in
the LGM may result from significantly declined moisture transferred from the North Atlantic
Ocean due to the orographic blocking (establishment of the northern European ice sheet) of
the westerlies. Meanwhile, the weakening or shutdown of the AMOC may induce the
mitigation of the ocean-continental pressure gradients (Rodwell et al., 1999) and thereafter
diminish the moisture delivered by both the westerlies and EASM (Wu and Wang, 2002;
Ivanova, 2009). It is postulated that, during the YD event, the relationship between the
Rossby wave pattern of the upper-level westerlies and the tropical convection intensity may
exert an influence on the precipitation regime over the low latitude Asia and thereby promote
widespread droughts (Staubwasser and Weiss, 2006). Moreover, impeded moisture conveying
94
by the westerlies (Chiang et al., 2015) along with the southward displacement of summer
mean latitudinal position of Inter Tropical Convergence Zone (ITCZ) (Haug et al., 2001;
Fleitmann et al., 2003; Broccoli et al., 2006; Yancheva et al., 2007) would have exerted a
pivotal influence on the less moisture supply of the Asian monsoon system. Furthermore, in
this study, the four playa phases exhibit broadly concurrent phases of low values on northern
Hemisphere temperature and insolation curves (see yellow bars in Fig. 5-9), suggesting
moisture deficits in response to the coupled oceanic circulation and boreal summer insolation
variances.
5.6. Conclusions
A multidisciplinary investigation is conducted on a 13.35 m lacustrine core retrieved from
Orog Nuur, in the Gobi Desert of Mongolia. Methods embracing sedimentological,
geochemical, palynological and ostracod studies are combined with geomorphological
evidence (sets of dated terrace ridges and moraines) in order to illustrate the vegetation
development and hydrologic history during the last ~ 50 ka. For the first time, in the Gobi
Desert, semi-quantified moisture and thermal sequences that trace back to the MIS 3 are
presented. The main conclusions are summarized as follows:
In Gobi Desert of Mongolia, the MIS 3 experienced sufficient moisture supply in particular
between ~36 ka and ~24 ka; MIS 2 was subjected to cool temperature and moisture-deficient,
which was interrupted by two exceedingly cold and dry playa phases related to the LGM and
YD event; the early Holocene exhibited ameliorated climatic condition characterized by
higher lake levels. Moreover, the merely local vegetation imprints (palynological spectrums)
may be responsible for the inconsistency or even controversy between the palynologically and
geochemically reconstructed hydrological signals. Thus, in this arid realm, a holistic view of
different proxies in conjunction with the consideration of geomorphological features
surrounding the lake as well as in the higher catchment is necessary. Furthermore, we need to
bear in mind that palynological imprints indicate merely the vegetation characteristics in the
catchment. Geochemical factors suggest the redox and antigenic state of the core sediments,
they are however not direct fingerprints of the lake level variances. In order to better discern
hydrological states, direct imprints such as aquatic organisms need to be focused on.
A sharp transition from the late Pleistocene to the Holocene (i.e., Termination I) is illuminated
by palynological and geochemical imprints. Lower area of the Orog Nuur catchment was
dominated by Artemisia steppe in the late Pleistocene and was altered to Chenopodiaceae
95
desert steppe in the Holocene. The water body in the Holocene appears to be a distinct
alkaline environment which was subjected to frequently allogenic input and disturbance of the
late Pleistocene anoxic states.
The main humid pulse in MIS 3 might have been the main driving mechanism for the MIS 3
glacial advance, while the pronounced low temperature in the higher elevated catchment in
the eastern Khangai Mountains is presumably the forcing factor for the LGM glacial advance.
The early Holocene in the Gobi Desert experienced the other humid pulse, which was
concurrent with lacustrine conditions and the degradation of the permafrost features as well as
the glacial retreat.
Four major arid playa phases (~47 ka, ~37 ka, ~19 ka and ~13-~11 ka) were determined, of
which the latter two sand layers (i.e., the LGM, YD event, respectively) may provide an
opportunity to be labelled as chronological benchmarks for other lacustrine sequences in the
Gobi Desert of Mongolia. Nonetheless, further investigations still need to be carried out to
test its reliability in a larger spatial scale.
In the central to southern Mongolia, the late Quaternary moisture and thermal history may be
modulated, if not controlled, by coupled atmospheric components embracing both westerlies
and the propagation of the East Asian Summer Monsoon into the Asian interior, albeit more
details with respect to the quantified contribution from these systems remain an open
question.
96
Fig. 5-S1: Diagram of analyzed taxa of pollen, fungal spores, aquatic algae and non-pollen
palynomorphs through the core ONW II plotted against the age and depth. All taxa were
aggregated into groups consist of panel (A) arboreal plants, humidity indicators, aquatic
algae, and panel (B) aridity indicators and grazing indicators.
97
“It is now clear that lacustrine sediments and
sedimentary rocks represent one of the best archives for
paleoenvironmental information available within the
entire realm of terrestrial settings” (William M. Last and
John P. Smol, 2002)
6. Geochemical imprints of coupled paleoenvironmental and provenance change in the
lacustrine sequence of Orog Nuur, Gobi Desert of Mongolia
Kaifeng Yu 1*
, Frank Lehmkuhl 1,Bernhard Diekmann
2, Christian Zeeden
1, Veit Nottebaum
1, Georg Stauch
1
1 Department of Geography, RWTH Aachen University, Templergraben 55, 52056 Aachen,
Germany
2 Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Telegrafenberg
A43, 14473 Potsdam, Germany
In the arid environment, due to the scarcity of a continuous terrestrial archive, lacustrine
sequences are often employed as a paleoenvironmental repository. However, numerous spatial
and temporal heterogeneities exist concerning previously studied sites in arid central Asia.
Furthermore, surveys using a XRF core scanning technique on lacustrine sequences retrieved
in hyperarid desert settings are largely rare. Hence, two parallel sediment cores (ONW I;
ONW II) were retrieved from Orog Nuur, in the Gobi Desert of Mongolia. Continuous, high-
resolution elemental abundances at a 1 cm scanning step size were examined in core ONW II
using XRF core scanning. Based on multivariate statistical evaluation, the bulk-geochemistry
of the core sediments are governed by (i) grain-size composition, (ii) authigenic productivity
(Ca, Cl, CaCO3) in an alkaline environment, (iii) allochthonous organic material (TOC and
C/Natomic), and (iv) terrigenous input via fluvial inflows, as well as quasi-constant aeolian
input through the late Quaternary (Al, Si, K, Ti, and Fe). To constrain the data quality,
elements with high error margins relative to measured peak areas and those elements/proxies
below the significance level during the multivariate statistics are excluded for
environmental/provenance implications. Disparate source lithotypes, as well as authigenic
productivity of the lake system existed before and after Termination I. The Holocene was
dominated by a distinct high productivity alkaline environment with more felsic and alkaline
input relative to the late Pleistocene. This might be attributed to an increased hydrodynamic
98
strength of riverine inflow and/or intensified erosion and weathering of felsic source rocks in
the upper catchment of the Orog Nuur. Therefore, in order to gain a better understanding of
the bulk-geochemistry of lake sediments, the coupled provenance and environmental
signatures, as well as land surface processes in the catchment need to be systematically
discerned. Thus, the XRF core scanning data obtained in this study would have practical and
complimentary merit for other lacustrine studies focused on the desert realm across the globe.
6.1. Introduction
Lacustrine sequences are critical archives for the reconstruction of climate and provenance
signatures. In particular, in arid central Asia, due to a scarcity of continuous loess-paleosol or
oceanic archives, lacustrine records were often employed as Quaternary paleoenvironmental
repositories (Boyle, 2001; Mischke et al., 2005). Southern Mongolia is located on the margin
of the westerlies-dominated arid central Asia and the East Asian Summer Monsoon domain of
eastern Asia (Chen et al., 2008). Acquisition of a continuous and chronologically reliable past
environmental record in this region is of substantial importance in refining our understanding
of comprehensive paleoenvironmental patterns and possible driving mechanisms. However,
numerous spatial and temporal heterogeneities exist concerning the lacustrine sequences here.
Compared with more intensively studied lake records in northern China and northern
Mongolia/Lake Baikal catchment of Russia, due to the remoteness of the region, only two
continuous lacustrine records were previously reported in the Gobi Desert of Mongolia,
namely Bayan Tohomin Nuur (nuur = lake; Felauer, 2011) and Ulaan Nuur (Lee et al., 2011).
Nonetheless, these two cores cover only the last ~15 ka. Furthermore, a commonly high
reservoir effect (contributing to 14
C dating uncertainty) of the non-varved lacustrine
sediments, as well as a lack of datable organic material in this arid context have largely
hampered a robust age-depth reconstruction (Felauer, 2011; Lee et al., 2011). A longer record
along with a well constrained chronological model (for instance using Bayesian age-depth
modelling) is therefore indispensable in providing a complementary repository to unravel the
aforementioned issues.
99
Fig. 6-1. Present-day distribution of geologic terranes in the Orog Nuur catchment. Panel A:
simplified land cover transect of Mongolia: mountain taiga, forest steppe, steppe, desert
steppe, and Gobi Desert in the south. Panel B: schematic geological setting of the catchment,
which is marked by dashed line. Northern region of catchment is dominated with Devonian-
Triassic felsic quartz syenite, granite, plagiogranite, and alkaline sediments, accompanied by
patchy intermediate mafic fractions. The southern region of Orog Nuur exhibits more of
mafic/ultramafic basalt and andesite-basalt rocks relative to the northern catchment. Alkaline
syenite occurs sporadically in the lower reach of Orog Nuur catchments. The depositional
basin is bounded by eastern Khangai in the north and the Gobi Altai Mountains in the south.
Among a suite of multidisciplinary studies on argillaceous sediments, geochemistry appears
to be a promising tool for deciphering the interplay between environmental change, source
lithotypes and sediment bulk-composition (Boyle, 2001). When considering late Quaternary
100
lacustrine sediments, the bulk-geochemistry may be controlled by source terranes, authigenic
or allogenic input, which may be modulated by past environmental conditions, while
pedogenesis and diagenesis exert merely limited overprints (Yu et al., 2016). Knowledge of
the downcore variability of major, trace, and minor element abundance along with field
investigation and careful examination of previous geologic mapping will enable us to
decipher the climate-induced provenance change throughout the depositional processes. On
the other hand, surveys considering the bulk-geochemistry and corresponding environmental
interpretations in the marine realm have been systematically reviewed (Calvert and Pedersen,
2007), whilst elucidations of the elemental fingerprints incorporated in the lacustrine
sediments still await more investigation (Roser and Korsch, 1988; Norman and De Deckker,
1990; Sinha et al., 2006). In particular, in contrast to conventional XRF measurement using
pressed pellets, the application of high resolution, time saving, and continuous XRF core
scanning to lake sediments has only attracted limited attention in the less than ten years since
its earlier applications in the marine realm (Melles et al., 2012). The XRF scanning technique
has not yielded a complete consensus on how the provenance, depositional environment, and
corresponding earth surface processes affect a suite of elements in different lacustrine settings
(Richter et al., 2006; Shanahan et al., 2008). A recent review by Davies et al. (2015)
highlights that several studies have been conducted to interpret elements, ratios and associated
environmental interpretations in the lacustrine realm. However, those implications should not
be taken as universally applicable, as there is to date rare XRF core scanning data that has
been generated in the hyperarid (desert) setting where largely no varved laminae can be
observed in the lacustrine sequences.
This work aims to provide a complementary XRF scanning logged record to fill in the gaps in
the above mentioned spatial/temporal heterogeneity of data repositories in the hyperarid
desert setting. In this study, major and trace element contents accompanied by calcium
carbonate concentration and C/Natomic ratios of the Orog Nuur lacustrine sequence are
examined in an attempt to: (i) test the possible plots of element ratios that could be employed
to extract the broad pattern of diversified source regions throughout the depositional period;
and (ii) ultimately evaluate the set of multi-proxy fingerprints and parse out the interplay
between the coupled past environmental processes, land surface processes, and provenance
change in the arid depositional system of the Orog Nuur catchment.
101
6.2. Regional setting
The Orog Nuur (45°01’-45°04’N 100°33’-100°53’E; ~1,219 m a.s.l.) is located in a
hydrologically closed basin system in the Valley of Gobi Lakes (Fig. 6-1). It is a brackish lake
subject to desiccation and occasionally turns into playa system. The Tuyn Gol (gol = river) is
the main inflow originating from the southern slopes of the Khangai Mountains around 220
km north of the lake. The continental climate of Gobi Desert is characterized by a dry / cold
winter with limited snow. More than 65% of the rainfall occurs in the summer. Annual
precipitation reaches ~100 mm in the vicinity of the Orog Nuur in the Gobi Desert of
Mongolia, while the higher elevated Khangai Mountains receive up to ~400 mm/a. The mean
annual air temperature is -2 to 5 °C. The mean air temperatures during July and January in the
Gobi Desert are ~16 °C and ~-20 °C, respectively (Felauer, 2011). The Valley of Gobi Lakes
(1,400-1,800 m a.s.l.) is an elongated intramontane depression between the Siberian Craton
and the Tarim and Sino-Korean Cratons (Baljinnyam et al., 1993; Cunningham et al., 2005).
Paleozoic volcanic and plutonic rocks are exposed in the basin (Fig. 6-1). The southern part of
the Orog Nuur watershed is represented by the tectonic escarpment of the Gobi Altai, as well
as gently inclined alluvial fans (Baljinnyam et al., 1993). As illustrated in Fig. 6-1, the
northern catchment (Tuyn Gol watershed) is dominated with Devonian-Triassic felsic quartz
syenite, granite, plagiogranite, and alkaline sediments, accompanied by minor proportions of
(intermediate) mafic rocks. The southern watershed exhibits more mafic to ultramafic basalt
and andesite-basalt rocks relative to the northern catchment. The Orog Nuur might have
occupied a much larger area in the Eemian and Marine Isotope Stage 3 (Lehmkuhl and Lang,
2001).
6.3. Material and methods
6.3.1. Core retrieval and Bayesian age-depth modelling
During the playa phase in 2007 and 2008, two parallel sediment cores (ONW I: 6.00 m,
45°03’48”N, 100°34’39”E; ONW II: 13.35 m, 45°04’28”N, 100°35’08”E, 1,219 m a.s.l.)
were recovered from the western part of Orog Nuur (Fig. 6-1B). The core was opened,
described and documented in the lab. Samples were separated and transported to (i) RWTH
for grain size and TOC analyses, and (ii) AWI Bremerhaven for X-ray fluorescence scanning
and X-ray powder diffraction analyses. The study here is conducted primarily on the longer
core ONW II.
102
Fig. 6-2. Lithostratigraphy and Bayesian age-depth modelling for core ONW II. R package
Bchron (Parnell et al., 2008) was employed. Gray shaded area represents maximum and
minimum age-depth estimates based on 100,000 smooth spline fits through the calibrated age
distributions (95% highest density region). The Bayesian age-depth model was further cross-
validated by several independent approaches: (i) two ages from the parallel core ONW I
(marked as black rectangles), (ii) sand layer and luminescence-determined age model of
Ulaan Nuur (Lee et al., 2011), (iii) downcore variance of CaCO3 concentration.
In total ten radiocarbon ages were determined from bulk materials (Tab. 6-1; Fig. 6-2) using
accelerator mass spectrometry (AMS) at the Erlangen-Nürnberg University and subsequently
calibrated to calendar years using CALIB rev. 7.1 (Stuiver et al., 1998) with the latest IntCal
13.14c calibration curve (Reimer et al., 2013). All radiocarbon ages are presented as
calibrated years (cal a BP) with a 2σ error bar (Tab. 6-1). The upper 24 cm of the core ONW
II were not retrieved. The R package “Bchron” (Parnell et al., 2008) was employed here to set
up a Bayesian age-depth model for core ONW II (Tab. 6-1; Fig. 6-2) including its calibration
using the IntCal calibration curve mentioned above. Reservoir effects at different anchor
points were assessed by (i) identifying Termination I in bulk-geochemical (sharp increase of
Ca peak areas, and CaCO3 %; Lauterbach et al. 2011) and palynological sequences (sharp
increase of pollen grains/concentration; Murad, 2011), and (ii) comparing the Younger Dryas-
related sand layer in Orog Nuur and Ulaan Nuur (Fig. 6-1A; Lee et al., 2011). All of the
radiocarbon ages were first subtracted by the reservoir effect and then computed to calibrated
103
calendar years and used in the establishment of the Bayesian age-depth model (Tab. 6-1; Fig.
6-2). The exact implementation procedures can be reproduced using appended R script. In
addition, two radiocarbon ages were determined for core ONW I (386 cm, 588 cm) to
compare and validate the timing of stratigraphic units of the counterpart depths in core ONW
II (Fig. 6-2).
Table 6-1 The AMS 14
C ages were calibrated to calendar years with 2 σ standard deviation
using the CALIB rev. 7.1 (Stuiver et al., 1998) with the latest IntCal13.14c (Reimer et al.,
2013). According to the estimated real age based on the lithostratigraphy, raw radiocarbon
ages are subtracted by a reservoir effect of ~3,400±2,100 a BP before computing to
calibrated ages and generating the Bayesian age-depth model as given in Fig. 6-2.
Core
Nr.
Dept
h
(cm)
Lab Nr. Dating
material
14C ages
(a BP)
δ13C
(%)
2σ (cal a
BP)
(95.4 %)*
Estimated
real age
according to
lithostratigr
aphy
(cal a BP)*
Calibrated
Age based on
Bayesian age-
depth
modelling (cal
a BP)
Median Age
based on
Bayesian age-
depth
modelling (cal
a BP)
ONW
II
94 Erl-15622 Bulk
material
12,581±
103
-25.4 14,325-
15,192
- 5,054-16,854 10,697
ONW
II
199 Erl-15623 Bulk
material
13,242±
85
-24.2 15,691-
16,138
11,000-
13,000
5,988-17,523 11,499
ONW
II
271 Erl-15624 Bulk
material
17,733±
149
-25.4 21,042-
21,819
13,000-
18,000
10,905-22,893 17,703
ONW
II
392 Erl-15625 Bulk
material
17,713±
180
-24.5 20,945-
21,857
18,000-
19,000
10,827-22,924 17,046
ONW
II
571 Erl-15626 Bulk
material
19,738±
179
-23.8 23,344-
24,150
- 13,528-25,249 19,604
ONW
II
778 Erl-15627 Bulk
material
21,501±
217
-24.2 25,386-
26,122
- 15,408-27,018 21,685
ONW
II
1,19
2
Erl-15628 Bulk
material
46,103±
2,281
-25.4 44,908-
49,914
- 37,748-49,716 45,303
ONW
II
1,27
2
Erl-15629 Bulk
material
40,429±
1,340
-24.9 42,221-
46,226
- 34,226-47,355 40,873
ONW
I
386 Erl-12107 Bulk
material
16,020±
105
-28.1 19,049-
19,560
18,000-
19,000
- -
ONW
I
588 Erl-12108 Bulk
material
17,642±
112
-23.4 21,020-
21,653
- - -
* The reservoir effect is determined by taking average of the difference between the boldface ages in these two columns.
6.3.2. Grain size analysis
The grain size distributions (GSDs) of 258 samples from ONW II and 114 samples from
ONW I at a 5 cm interval were determined using a Beckman Coulter LS13320 Laser
Diffraction Particle Size Analyzer. All measurements were performed uniformly without
hydrochloric acid treatment (Felauer, 2011; Schulte et al., 2016). 700 µl of 35% H2O2 was
added to remove the organic components. Samples were subsequently dried at 70 °C for two
days. Sodium pyrophosphate was added to avoid coagulation. The final GSD represents the
average of two subsamples. Each of them was measured twice to ensure the reliability. In any
104
case of conspicuous offsets exist between subsamples, the procedure was repeated for the
sample (Schulte et al., 2016).
6.3.3. TOC, CaCO3 and C/Natomic analyses
Fig. 6-3. Downcore variance of abundance of the major and trace elements expressed by
integrated peak areas (total counts per second), accompanied by the C/Natomic ratios, CaCO3
content, Rb/Sr ratio (lower values= higher catchment weathering; Davies et al., 2015), Al/Si
ratio (lower values=higher coarse-grained sands; Davies et al., 2015), and the XRD
determined minerals in sparser intervals. Silicon and K share similar patterns as Al, whilst
Mn and Co share similar patterns as Fe. Further details are presented in the supplementary
material of this paper. The grey bars depict the sand layers inferred from the granulometric
and lithostratigraphic characteristics of the core, and the dashed line mark the transition of
Termination I. The consistency between the grey bars and the elements spikes implies that the
sand fractions (Factor 1 as determined by robust statistics; Fig. 6-4) have played a pivotal
role in the alteration of bulk-geochemistry of the lacustrine sediments.
In total 258 samples (ONW II) were dried at 36 °C for 24 hours. The prepared samples in zinc
capsules were analyzed in a CHNS Analyzer EA3000. The Scheibler gas method (DIN
19684) was used to calculate the CaCO3 content. Total organic carbon (TOC) was computed
following Scheffer and Schachtschabel (2002). The C/Natomic ratios of core ONW II were
calculated for the following discussion (Meyers and Lallier-Vergès, 1999).
105
6.3.4. X-ray fluorescence scanning and X-ray powder diffraction analysis
The X-ray fluorescence (XRF) analysis was conducted using an Avaatech XRF Core Scanner
configured with a Canberra X-Pips 1500-1.5 detector (20 s dwell time, slit 10 mm, 10, 30
keV, 300 and 700 µA) (Richter et al., 2006) at the AWI Bremerhaven. For core ONW II, in
total 1,335 results at a 1 cm scanning step size were retrieved. Subtraction of a background
curve, application of statistical corrections for physical processes in the detector, and
deconvolution of overlapping peaks were performed using a scanner equipped WinAxil
package (NIOZ and Avaatech, 2007). Element abundance is given in integrated peak areas
(total counts per second or cps). To help discern their environmental and/or provenance
implications, the whole set of elements were further divided into four groups based on robust
multivariate statistics as outlined in next chapter (Fig. 6-3).
To further interpret the bulk-geochemical composition of samples from different
sedimentological settings, a standard X-ray diffraction (XRD) technique using a Philips
X’Pert MPD diffractometer with a divergence slit using array Cu Kα radiation (40 kV, 50mA)
was employed to detect the bulk mineralogical composition of 14 samples at the depth of 50,
200, 300, 350, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300 cm, respectively (Fig. 6-
3). Minerals were identified from XRD patterns of samples at 3.34 Å (quartz), 3.24 Å (K-
feldspar), 3.19 Å (plagioclase), 3.024 Å (calcite), 6.15 Å (mica), 14/7.02/4.72 Å (kaolinite-
chlorite/chlorite), 3.57 Å (kaolinite) 8.47 Å (hornblende), and minor spikes at 10/5 Å (illite).
The measurement was performed from 2-35° 2θ with scan speed of 0.02° 2θ/2 sec. The
integrated peak areas (total counts) of the above mineral groups were calculated and
transformed into mineral percentages using the freeware MacDiff (Petschick et al., 1996). A
suite of original measurements of Stein et al. (1994) and Vogt (1997) that were previously
carried out at AWI were compared to ensure the comparability between the peak areas and
percent calculations.
6.3.5. Robust multivariate statistics
To provide a quantitative manner in which to segregate the whole set of multi-proxies into
detailed assemblages, a robust multivariate statistical analysis is computed using the R
package “Robustfa” (https://cran.r-project.org/web/packages/robustfa/robustfa.pdf). A
detailed computing process and the manner of data interpretation were given in Yu et al.
(2016). The robust evaluation parameters for each factor and sediment sample are presented
in Tab. 6-2. Those elements with high positive or negative (> 0.75) loadings are shown in
106
boldface and will be included for further discussion regarding their integrated environmental
processes, provenance, and land surface processes.
Table 6-2 Standard deviation, variance/cumulative proportion, multi-proxies loading for each
factor, and communalities for each proxy generated by robust multivariate statistics. High
positive or negative (> 0.75) loadings are marked in boldface. Blank values represent those
loadings which are under significance level in robust multivariate statistics. Communalities
for each element are computed by taking sum of the seared loadings, it can be referred to the
length of the element arrows in loadings plot (Fig. 6-4A), a value greater than 0.90 suggests a
well representative of this proxy in the statistical model. Factors 1 (26.4%) and 4 (25.9%)
explain more than have of the variance, they are therefore illustrated in the biplots of Fig. 6-4
for further implications. More details concerning the statistics refer to Yu et al. (2016).
Multi-proxies Factor 1: Sand
fraction
Factor 2: Authigenic
productivity
Factor 3: Organic
material
Factor 4:
Terrigenous input
Communalit
y estimates
Al -0.249 -0.129 - 0.930 0.944
Si - -0.117 - 0.911 0.844
S - -0.448 - - 0.201
Cl - 0.756 - -0.118 0.585
K -0.340 - - 0.935 0.990
Ca -0.494 0.780 - - 0.852
Ti -0.459 -0.105 - 0.826 0.904
Cr -0.243 0.197 - 0.194 0.135
Fe -0.554 - - 0.773 0.904
Rb - -0.367 - 0.675 0.590
Sr -0.108 0.697 - -0.153 0.521
Zr - -0.109 - 0.724 0.536
N (CNS) -0.804 -0.147 0.280 0.141 0.766
CaCO3 -0.548 0.779 - -0.244 0.967
TOC -0.382 - 0.954 - 1.056
C/Natomic - - 0.818 - 0.669
Mean grain-size 0.914 -0.242 - -0.234 0.949
Clay fraction -0.780 0.470 - - 0.829
Silt fraction -0.926 0.122 - 0.269 0.945
Sand fraction 0.934 -0.258 - -0.212 0.984
Standard
deviation
5.281 3.097 1.685 5.172 -
Variance
proportions/%
26.4 15.5 8.4 25.9 -
Cumulative
proportions/%
26.4 41.9 50.3 76.2 -
6.4. Results
6.4.1. Lithostratigraphic units and Bayesian chronology
According to the Bayesian age-depth model, the basal age of the core ONW II was
determined to be between 38 and 52 ka (Fig. 6-2). Termination I manifests as a remarkable
transition in geochemical patterns in core ONW II (Fig. 6-3), namely an abrupt increase of
CaCO3, indicating the onset of the Holocene unit in the age model (Fig. 6-2) (Lauterbach et
107
al., 2011). To further corroborate the depth of Termination I, a luminescence-constrained
Younger Dryas sand layer in Ulaan Nuur sediments (Fig. 6-1A) is used. In this adjacent core,
the sand layer was determined to be some 13-11 ka (Fig. 6-2). Thus, ~205 cm is presumed to
be ~11,000 a BP, which is ~4,900 years younger than that in the age model. The age of
sediment at ~248 cm is assigned to ~13,000 a BP, which is ~3,000 yrs younger than in the
Bayesian age model. Likewise, based on the estimation of the real ages of the
lithostratigraphy, the raw radiocarbon ages were subtracted by a reservoir effect of c.
3,400±2,100 yrs (Tab. 6-2) and then computed to calibrated calendar years and employed in
the establishment of the Bayesian age-depth model (Fig. 6-2). In light of Felauer (2011) and
Lee et al. (2011), a reservoir effect of greater than 3,000 yrs in the Orog Nuur cores is highly
feasible. Furthermore, the lowermost two ages are near the limit of radiocarbon dating.
However, the application of the newly established calculation curve IntCall13, as well as the
employment of the Bayesian modeling still assures a relatively reliable basal age that is
younger than ~50 ka (Tab. 6-1; Fig. 6-2).
On the basis of lithostratigraphic, granulometric, and geochemical characteristics, the entire
sequence is delimited into five units:
Unit I (1,335-390 cm; ~50-~19 cal ka BP)
Unit I is dominated by greyish clayey-silty sediments (on average 60-80%; Fig. 6-2) with
intercalations of several brownish sand layers that are marked as grey bars in Fig. 6-3. CaCO3
remains generally stable with low values (~10%) within Unit I, while the C/Natomic ratio
displays a relatively varied pattern (Fig. 6-3) with several laminations with values greater than
20.
Unit II (390-350 cm, ~19-~18 cal ka BP)
Unit II is a salient brownish coarse sand layer which is also captured by the parallel core
ONW I (Fig. 6-2). The sand fraction ranges from 91.5% to 96.1%. CaCO3 abundance exhibits
extremely low values while C/Natomic ratios display high values with oscillations (Fig. 6-2).
Unit III (350-248 cm; ~18-~13 cal ka BP)
Unit III is a dark greyish clayey-silty layer similar to Unit I. The sand fraction ranges from
10% to 35% with an abrupt increase in the basal part of Unit III to ~35% and a subsequent
decrease to 10% at 283 cm. The CaCO3 and C/Natomic ratio depict similar patterns to Unit I.
108
Unit IV (248-205 cm; ~13-~11 ca ka BP)
Unit IV is dominated by the sand proportion (50-90%). The sand layer is also present in the
parallel core ONW I and the adjacent Ulaan Nuur (Fig. 6-1; Lee et al., 2011). CaCO3 content
remains similar to Unit III, while the C/Natomic ratio shows more fluctuations similar to Unit II.
Throughout Unit IV, the S content exhibits low values (Fig. 6-3).
Unit V (205-25 cm; <~11 cal ka BP)
Unit V is characterized by fine sediments with the highest clay proportion (30-50%) and the
lowest sand fraction (1-10%). A sharp increase in CaCO3 (calcite; Fig. 6-3) and concomitantly
diminished S contents are present in Unit V. C/Natomic ratios decrease from ~20 to <10 upward
and increase incrementally approaching the top of the core.
6.4.2. Elements/minerals downcore variance and multi-proxy assemblages revealed by
multivariate statistics
The major and trace element concentrations, as well as mineral compositions throughout the
core ONW II were plotted against the depths and stratigraphic units (Fig. 6-3). In light of the
multivariate statistics (Fig. 6-4; Tab. 6-2), the whole set of elemental compositions and other
proxies are evaluated using a robust factor analysis. They are divided into four factors: (1)
Factor 1 (variance proportion: 26.4%) is positively correlated with mean grain-size and sand
percentages of the sediments and negatively correlated with the N content and silt/clay
fraction of the sediments. (2) Factor 2 (15.5%) exhibits significantly high loadings of Cl, Ca
and CaCO3 content. In general, Ca and Sr concentrations display a unique pattern that
resembles CaCO3 and hornblende, with relatively low abundances throughout the late
Pleistocene and sharp increases after Termination I. Cl exhibits a long-term trend of upcore
increase along with superimposed fluctuations. In general, the factor is an indicator for the
authigenic productivity of the lake system (see following discussion). (3) Factor 3 (8.4%)
delineates higher loadings for TOC and C/Natomic and an insignificant correlation with
elemental compositions and grain-size composition. (4) Factor 4 (25.9%) has significantly
high loadings of Al, Si, K, Ti, and Fe. This set of elements exhibits higher abundance in Units
I, III and V (relatively lower in Unit I), while the contents in Units II and IV are markedly
lower. They share broadly similar patterns to mica and chlorite. This factor is explained as
terrigenous input brought by two pathways: (i) riverine inflows via Tuyn Gol, and (ii) quasi-
constant aeolian inputs. In addition, note the relatively high variability of the element
109
concentrations of, in particular, Unit I (Fig. 6-3), which may result from the frequently
occurrence of sand layers as illustrated by the grey bars in Fig. 6-3. In this scenario, insight
into the bulk-geochemistry of each unit is more readily obtained in the dispersion plots,
wherein Units I and III share broadly similar median values and upper / lower quartiles (Fig.
6-3; supplementary figure). Factors 1 (26.4%), 4 (25.9%), and 3 (15.5%) explain ~70% of the
multi-proxy variations; they are the primary governing factors for the sediment bulk-
geochemistry.
Fig. 6-4. Loadings and scores plot of the multi-proxy data set. Panel A: loading plot of the
robust Factor 1 (grain-size) vs. 4 (terrigenous input). Panel B: score plot of the robust Factor
1 vs. 4. In multivariate statistics, the maximum direction of variance is regarded as axes.
Rotation is performed to get varimax rotated axis (x- and y-axis in Panel A) during the
analysis attempting to archive a higher loading for each elements (Tab. 6-2). Cosine of the
angle between the proxies and varimax rotated axes are factor loadings, length of the arrows
are corresponding to the proxy communalities. In panel B, all units of samples are defined
based on their lithostratigraphic units.
In terms of the minerals, mica, chlorite, quartz, plagioclase, K-feldspar, hornblende, and
calcite are determined at coarser intervals throughout the core ONW II (Fig. 6-3). Amongst
those minerals, (1) quartz and plagioclase display only minor variation through the core; (2)
mica and chlorite exhibit a highly coupled pattern that has higher values in the lake phases
(Unit I, III, and V); (3) calcite and hornblende have a similar pattern with higher values
specifically in the Holocene (Unit V) relative to the Pleistocene units; (4) K-feldspar denotes
110
a broadly reversed pattern compared with that of mica and chlorite, and appears to have a
higher content corresponding to the sand layers (grey bars in Fig. 6-3). In general, the set of
XRD data shed light on the general mineralogical composition of the studied core, and
thereby aid in further interpretation of the XRF scanning data.
6.5. Discussion
6.5.1. Evaluating the quality of the X-ray scanning data
As mentioned above, the retrieved XRF core scanning data are expressed in semi-quantified
integrated peak area/total counts per second (cps) without conversion to oxide wt % or molar
abundance.
Amongst the entire suite of elements, Ni, Cu, Zn, Ga, Br, Au, Pb, and Bi have a relatively
high error margin compared to their measured peak areas. They are therefore removed from
the multivariate statistics (for detailed data and error margin see the supplementary material of
this paper). In the statistical report (Tab. 6-2), the proxies that are under significance level are
ruled out for the following discussions as well. The remaining set of elements show measured
peak areas that are well above the theoretical detection limit of the Avaatech XRF scanning
infrastructure (Richter et al., 2006; NIOZ and Avaatech, 2007). Certain low count rates (in
particular for light elements such as Si) may be ascribed to intervals with very coarse-grained
sediments such as those in Unit II and Unit IV in this core (Richter et al., 2006; Shanahan et
al., 2008; Weltje and Tjallingii, 2008; Ohlendorf et al., 2015). However, as demonstrated in
the recently published monograph concerning the XRF scanning technique and its
applications on marine, fluvial, and lacustrine sediments (Bertrand et al., 2015), in general,
the precision of data obtained by XRF core scanning is not significantly altered by grain-size
variations. They correct the XRF peak areas for water content and grain-size, which only
slightly improves the correlation between XRF peak areas and Inductively Coupled Plasma
Mass Spectrometry (ICP-MS) determined bulk-geochemistry concentrations. This
improvement is, however, relatively minor; the difference between the correlation coefficients
is never significant at p < 0.05 level (Bertrand et al., 2015). Furthermore, Schillereff et al.
(2015) demonstrate for the first time that the employment of different XRF scanning
instruments (mainly Avaatech and Itrax, etc.) yields similar elemental patterns, implying a
robust and sound quality of the retrieved data. Meanwhile, Dulski et al. (2015) analyzed
parallel subsamples using XRF scanning and ICP-MS, also revealing a systematic relationship
between the scanned data and element concentrations.
111
In terms of late Quaternary lacustrine sediments, although diagenesis may indeed exert certain
influence on the fate of bulk-composition (Johnsson, 1993), it is, however, a less crucial
aspect compared with the alteration of paleoenvironment and source lithotypes in the entire
catchment system. Pettijohn (1973) concluded that due to the limited burial time, calcite
cements along with the negligible quartz overgrowths are virtually the only diagenetic
overprints. Thus, source terranes, paleoenvironment-induced weathering and transportation
adaptations are more likely the governing factors for the late Quaternary lake sediments. On
this account, the following discussion is generally demarcated and outlined in twofold: (i) the
paleoenvironmental (weathering, land surface processes) implications, and (ii) provenance
signals.
6.5.2. Governing factors for sediment bulk-geochemistry
In the marine realm, researches have been systematically undertaken to examining the
sediment bulk-geochemistry and its environmental interpretations (Calvert and Pedersen,
2007; Diekmann et al., 2008; Martinez-Ruiz et al., 2015). It has been suggested that
assemblages of the elements exhibit specific indications of the redox condition (Mn and Co),
diagenetic processes (Fe), authigenic productivity (Al and Ba) and the allogenic
aeolian/fluvial inputs (Zr and Rb) during sedimentary processes. Here, in the lacustrine realm,
a holistically refined view of the governing factors of sediment bulk-geochemistry, taken in
consideration of other multidisciplinary proxies, is employed using robust multivariate
statistics as a prerequisite for the following discussions.
6.5.2.1. Factor 1 (26.4%): Grain-size variation of the lacustrine sediments
This factor has the highest proportion, 26.4%, as determined by the factor analysis (Tab. 6-2).
In arid central Asia, aeolian sand plays a primary role in the terrestrial context (Kazancı et al.,
2016) and the northwest Pacific pelagic sediments (Pye and Zhou, 1989). The abundance of
the sand percentage (63-2,000 µm fractions) is also well presented as spikes for Al, Fe, and
Al/Si ratios (Fig. 6-3). In order to examine the sand-induced influence on the bulk-
geochemistry, all samples are plotted in the scores plot based on the multivariate statistics
(Fig. 6-4B). Samples with a great contribution from (aeolian/fluvial) sand fractions
particularly approach the positive end of Factor 1, while those samples of clay or silty-clay
sediments are scattered at intermediate to negative positions on the Factor 1 axis.
Interestingly, all coarse-grained samples from the Unit II (LGM) strata are relatively
clustered, while those from the Unit IV (YD) are more scattered. This may be because the
112
Unit IV strata correspond to a playa phase that is more frequently influenced by the riverine
input (mixture of both fluvial sands and finer suspended river sediments; Fig. 6-2), instead of
predominantly coarse-grained sands as in Unit II. In summary, the coarse sands have a large
influence on the sediment bulk-geochemistry via (i) fluvial inflows, and (ii) direct aeolian
inputs. However, it must also be remembered that the sediment bulk-geochemistry is not
solely a reflection of the sediment grain-size composition, indicated by the fact that that no
elements in Factor 1 are well above the significance level (Tab. 6-2).
6.5.2.2. Factor 2 (15.5%): Authigenic productivity of the saline/alkaline lacustrine
environment
Factor 2 has significantly high loadings of Cl, Ca, and CaCO3 (Tab. 6-2). Ca is generally
included in carbonates which are also common minerals in lacustrine environment (Tucker
and Wright, 1990). Calcite, low-Mg calcite, and rarely occurring aragonite are generally
authigenic precipitates in lake sediments while dolomite (along with quartz and feldspar)
could be regarded as detrital input (Sinha et al., 2006; Wünnemann et al., 2010). In core ONW
II, the abundance of calcite, Ca and CaCO3 share analogous patterns, implying that in this
study Ca is present mainly as calcite, and Unit V (Holocene) depicts notably higher authigenic
productivity relative to the late Pleistocene epoch (Fig. 6-3). In contrast, Al and Si display
lower values in the Holocene, acting as an analogue for plagioclase and K-feldspar (Fig. 6-3),
suggesting a non-productivity signature. Therefore, compared with the marine pelagic realm,
Al is not an indicator for the authigenic productivity. On the other hand, Sr has relatively high
loadings, but its content variation is still under significance level (Tab. 6-2). Sr behaves quite
similarly to Ca due to their similar hydro-geochemical characteristics (Calvert and Pedersen,
2007; Kylander et al., 2011). Likewise, Davies et al. (2015) also suggest that the presence of
Ca and Sr is commonly associated with authigenic carbonate minerals in catchments located
in arid and carbonate environments. In the lacustrine realm, halite is a ubiquitous species that
may partly be generated by re-precipitation from pore solutions (Sinha et al., 2006). Similar to
halite, the halogen element bromine may also be readily incorporated in halide salts. The
upcore increase of these halogen elements (Fig. 6-3) implies a higher salinity/alkalinity
approaching the upper part of core ONW II. Particularly in the Holocene, this high salinity
and/or alkalinity are corroborated by the significantly elevated CaCO3 abundance (Fig. 6-3).
In addition, Sulfur is in part negatively correlated with the Factor 2, albeit under the
significance level (Tab. 6-2). Sulfur might be present as sulfate (gypsum and anhydrite),
sulfide, and pyrite (Millot, 1970). As illustrated in Fig. 6-3, S exhibits higher content in Units
113
I-III, low values in Unit IV and is slightly elevated in the uppermost unit. In the late
Pleistocene units, the less disturbed lake states may have led to a relatively higher content of
sulfide and pyrite precipitation at the sediment-water interface. The sulfide minerals were then
almost entirely oxygenated when exposed in the sand/playa layer and subsequently produced
sulfate precipitation in the alkaline environment of Unit V. Alternatively, the sporadically
deposited gypsum and mirabilite in such a cold, dry lake system may also account for these S
spikes determined in Fig. 6-3. However, above all, the insignificance level of S loading for
Factor 2 (Tab. 6-2) suggests that sulfide or sulfate mineral genesis is of minor importance for
the bulk-geochemistry. This is also corroborated by clear evidence that above mentioned
minerals are not detected by the XRD analysis in this study (Fig. 6-3).
6.5.2.3. Factor 3 (8.4%): Organic material content
Factor 3 is represented by significantly high loadings of TOC and C/Natomic (Tab. 6-2). The
TOC content incorporated in the core sediments is relatively low (Fig. 6-2). The coupled
variation of TOC and C/Natomic values implies that the lacustrine system has merely minor
biogenic activity, and that the low content of the organic matter incorporated in the core was
brought into the depocenter via allogenic fluvial processes, given that C/Natomic ratios greater
than 20 indicate allochthonous input into the lacustrine system (Meyers and Lallier-Vergès,
1999).
6.5.2.4. Factor 4 (25.9%): Terrigenous components via riverine input and quasi-constant
aeolian input
Factor 4 has high loadings for Al, Si, K, Ti and Fe (Tab. 6-2). Clay or silty-clay is the
predominant sediment in the lacustrine environment (Millot, 1970). The fine detrital matrix
formed mainly from the weathering decomposition of the primary aluminosilicates, which are
the main host for Al (Calvert and Pedersen, 2007). On the other hand, Al may also be
incorporated in feldspar and micas (Millot, 1970). In core ONW II, Al and Si display broadly
identical patterns (Fig. 6-3), indicating a close link due to similar host minerals in fine
sediments, either in a feldspathic structure or as a set of clay minerals in water bodies (Millot,
1970). In addition, in an arid context such as the Gobi Desert, in situ evaporated alkaline
water was reported to be rich in Si and depleted in Al (Millot, 1970), which may account for
the lower Al abundance in Unit V when calcite or carbonates are the predominant minerals in
the water body (Fig. 6-3). In addition, several works suggest that the organic content in a
lacustrine environment may exert strong influence on the Al abundance (Davies et al., 2015).
114
However, in the arid context of the Orog Nuur, the TOC values are broadly no greater than 2-
3% (Fig. 6-2), thus making the above Factor 2 less important.
Due to the complex characteristics of its provenance ranging from fine clays to coarse sands
(Yu et al., 2016), Si presents an unclear indication of the grain-size composition (unpresented
in Factor 1; Tab. 6-2). Indeed, aeolian sands exhibit higher amounts of SiO2 (Yu et al., 2016).
However, in this context in Orog Nuur, Units II and IV may not be ascribed to purely aeolian
sand. Grain-size alone cannot be used precisely to conform that the coarse-grained layers in
this study are purely aeolian sands (Confroy et al., 2013). In a recent study on the Gobi Desert
archives, SiO2 content was found to be 71% (aeolian sands), 55% (lacustrine clay), 47%
(fluvial sands), 69% (sandy loess), and 36% (alluvial gravels), respectively (Yu et al., 2016).
This relatively lower Si content in the coarser-grained fluvial sand layer is also suggested by
Dulski et al. (2015) based on scanning of the Piànico paleolake sequence. Likewise, Hunt et
al. (2015) also demonstrate that increasing grain-size composition will not necessarily result
in an elevated Si value. Thus, the fluvial sands may indeed display lower Si abundance
relative to lacustrine clays in the core. In addition, as given in Yu et al. (2016), the sand
fraction of the fluvial sands may be as high as that of the aeolian sand, albeit more spikes in
finer fractions may be observed in the granulometic curves of fluvial sands. Thus, the
complex provenance of lacustrine sediments from both coarse sands and alluminosilicate
clays leads us to assume that the relatively coarse-grained layers (Units II and IV) may be
largely attributed to fluvial transportation, rather than purely aeolian sands. On the other hand,
in this aeolian sand and silt source region, the fluvial system normally experiences multi-cycle
deposition of the coarse material. The SiO2 values in this aeolian material show a significant
decrease through long-term weathering processes (Bridge and Demicco, 2008), rendering a
considerably lower SiO2 abundance of the fluvial sands detected by the core scanning in this
study. Multi-cycle deposition would account for the relatively lower SiO2 values in those
coarse-grained layers relative to the lacustrine clays in other units. Furthermore, the various
Al/Si ratios through the core indicate that the Si pattern is also not governed by the
terrigenous aluminosilicate constituents (Fig. 6-5; Richer et al., 2006), demonstrating a
twofold, mixed provenance for Si: (i) quartz in aeolian sands, and (ii) fine-grained terrigenous
aluminosilicates.
115
Fig. 6-5. Bivariate plots of major and trace elements in peaks areas (y-axis) against Al/Si (x-
axis) according to their stratigraphic units. Al/Si ratios indicate generally the grain-size
compositions of the bulk sediments, which display lower values/spikes according to the
coarse-grained sand layers (Fig. 6-3). The biplot of Ca vs. Al/Si seems like a useful tool to
properly discriminate the instinct (i) source rocks changes, and (ii) authigenic productivity in
comparison with the late Pleistocene units. This distinct Holocene samples characteristics are
more clearly elaborated in the scores plot of Fig. 6-4B.
In this study, K displays a divergent variance pattern compared with Ca and reveals
convergent characteristics with Si, Al and Fe (Figs. 6-3 and 6-4). The behavior may result
from mechanisms suggested by Millot (1970), namely, in young aqueous sediments, Ca is
preferentially fixed into carbonates while K enters silicates. Furthermore, as illustrated in Fig.
6-3, the most likely host for K in the Orog Nuur sediments is K-feldspar with partial
contributions from micas or chlorite, which may all be associated with allogenic fluvial
inputs, as well as the aeolian processes (Costa et al., 2014).
In core ONW II, hornblende and micas are the potential hosts for Iron (Fig. 6-3). In general,
hornblende is the main constituent of certain mafic source terranes in the catchments (Fig. 6-
1B) and has weak resistance to weathering (Millot, 1970). Consequently, decomposed and
retained hornblende together with micas all concentrate in fine clay sediments which are
liable to be transported into the Orog Nuur by hydraulic flow and/or mass movement (Nesbitt
116
and Young, 1996) from southern alluvial fans (Fig. 6-1). In general, Fe has two modes of
occurrence, namely the trivalent state and bivalent state when it accompanies Mg or K
(Millot, 1970). As illustrated in Fig. 6-3, Fe acts in a manner analogous to Al and Si. Thus,
rather than primary hornblende, Fe is mainly found in the micas and chlorite in the clayey
sediments, which seems to be the same case with Ti, Rb and Co (Fig. 6-3). Due to the short
burial time and resulting weak diagenetic influence, Fe may not be an indicator of diagenetic
processes in the lacustrine realm.
Furthermore, several other elements share similar patterns as that of the above elements, they
illustrate insignificant loadings for Factor 4. (1) Zirconium: there is ample evidence that Zr is
relatively stable and is almost exclusively mechanically transported and fractionated
(Pettijohn et al., 1973). Mukherji (1970) determined that in an acid aqueous media, Zr may
also exist in polymeric species, e.g., zirconyl halides in the case of higher Cl anion abundance
(Fig. 6-3). However, in terms of alkaline environments with higher concentrations of calcite
or carbonate (higher abundance of [HCO3−]+2[CO3
2−]; Chilingar et al., 1979; Dapples, 1979;),
zirconyl halides seem not to be the host for Zr. Here, the downcore Zr variance reveals no
association between sand fractions and Zr abundance. However, it displays certain links with
the quartz, plagioclase and K-feldspar abundance throughout the core, implying that Zr may
be correlated to the precursor lithotype-governed allogenic fluvial clastic input, but is not
necessarily a faithful recorder of aeolian input (Sinha et al., 2006). (2) Manganese: in spite of
the two sand layers (Units II and IV), the lacustrine phase throughout the core depicts quasi-
constant Mn abundance. In general, insoluble oxi-hydroxides (Mn (III) and Mn (IV) ion)
occur in oxygenated environments while soluble Mn (II) occurs in anaerobic environments
(Calvert and Pedersen, 2007). Thus, in terms of higher lake levels with suboxic to anoxic
water bottoms, more soluble Mn will be readily incorporated into the carbonate lattice and
thereby share variance patterns similar to Ca or CaCO3, which seems largely untenable in this
study (Fig. 6-3). The Orog Nuur therefore represents a frequently riverine inflow-disturbed
shallow hydrological environment, rather than a stagnant water body. (3) Cobalt: the element
Co behaves similarly to Mn and is generally enriched in clayey deposits (Costa et al., 2014).
Both Mn and Co are therefore depleted in sand layers (Fig. 6-3). A slightly lower value in
Unit V can be observed with respect to Co, albeit the broad pattern remains analogous to Mn.
This lowering may be ascribed to the sensitive response of the elements to the slightly
decreasing mica abundance (Fig. 6-3).
117
In summary, Factor 4, represented by Al, Si, K, Ti, and Fe, indicates the allochthonous input
into the lacustrine system. This terrigenous input implication is consistent with several other
works, including Kylander et al. (2011) and Davies et al. (2015).
6.5.3. Biplots of elements and scores plot as indicators of a distinct provenance signal
and high authigenic productivity of the lake system in the Holocene
There is broad consensus that rare earth elements (REE), which are rarely influenced by
diagenesis and metamorphic processes, are common indicators for provenance change
(Pettijohn et al., 1973). Here, in terms of the dominating mudstone, ratios between major and
trace elements were computed in an attempt to examine the possible lithotype signatures (Fig.
6-5). As postulated by Pettijohn et al. (1973), the Al/Si ratio is the commonly applied value in
discriminating the provenance of sandstone and mudstones. In general, higher Al/Si denotes
more clayey or detrital aluminosilicates while the quartz-rich sandstones have low Al/Si ratios
due to the virtual absence of clay-bearing silicates (Davies et al., 2015).
Distinct assemblages related to the lithostratigraphic units are discriminated in the biplots
against Al/Si (Fig. 6-5). Three main groups have been recognized: (i) Fe (K with similar
pattern) abundances are broadly altered by silicate contents in authigenic mud and allogenic
fluvial clastics brought by the Tuyn Gol. Due to the lack of a clay fraction, the Last Glacial
Maximum (LGM) sediments (Unit II) are distinctly distributed with low Fe and Al/Si values,
whereas the mud dominant sediments from Units I and III occupy the opposite end of the
biplot. Furthermore, apart from the lacustrine sediments in this study, the quasi-linear
regression (r=0.66-0.97; R2=0.43-0.97) pattern between Al/Si and Fe was also delineated in
the sandstones and argillites, wherein both depositional conditions and provenance
fingerprints might have been incorporated (Roser and Korsch, 1988); (ii) Mn (Zr and Co with
similar patterns), similarly, is also governed by clay and silt fractions. However, through
sand-dominated sediments may confound the pattern of Mn (Fig. 6-5), data points of the
LGM sediments (Unit II) are more scattered compared with those of Fe. The entire set of data
points is therefore less linearly correlated (r=0.18-0.70; R2=0.03-0.57) relative to the first
group of elements. In addition, as stated above, the whole suite of samples in the biplot of Zr
vs. Al/Si present a slightly more horizontal and scattered regression (r=0.36-0.61; R2=0.13-
0.38), implying that Zr is hosted in both clay enriched and depleted sediments, which might
have complicated the biplot pattern; (iii) Ca appears to be the distinct element that allows us
to discriminate between late Pleistocene and Holocene signatures. Before Termination I, the
sediments exhibit a virtually linear regression (r=0.06-0.97; R2=0.00-0.95) in a manner
118
analogous to Fe, suggesting a quasi-consistent alteration kinetics governed by the clay and silt
fraction input (Fig. 6-5). Nevertheless, although they share similar granulometric
compositions, the Holocene sediments in Unit V exhibit distinctly higher Ca values relative to
the granulometrically similar Units I and III (r=-0.42; R2=0.17) (Fig. 6-5). On the other hand,
the LGM and Younger Dryas sand layers (Units II and IV) represent distinctly different
patterns, namely the Younger Dryas sediments are more scattered relative to LGM sediments
regarding the Al/Si axis. Unlike the dominantly playa condition during the LGM, the Younger
Dryas may have been subject to frequent riverine inflows, resulting in a broader covering of
mud-, silt- to sandstone suites (Fig. 6-2). As a consequence, compared with those in Unit II,
the set of Unit IV data points is more scattered in Fig. 6-5.
6.5.3.1. The disparate provenance signatures and authigenic productivity of the
Holocene sediments
The set of late Pleistocene sediments exhibits coherent regression patterns in the biplots (Fig.
6-5), indicating insignificantly alteration of source lithotypes through Units I-IV. This quasi-
constant provenance delivery/authigenic productivity through Unit I to IV is also documented
in the broadly unbiased quartz, plagioclase, hornblende and minor biased Rb/Sr ratios
(catchment weathering) throughout the late Pleistocene (Fig. 6-3). Apart from Ca, all of the
above three groups of elements display a tendency of quasi-linear regression which is altered
by the amount of clay and silty-clay proportions, albeit Zr is slightly biased and scattered due
to contributions from both finer and coarse sand fractions. The constant delivery of riverine
inflows during the lake phase may have transported the felsic and weathered intermediate or
mafic plutonic rocks into the Orog Nuur (Fig. 6-1B), although this phase was interrupted by
two desiccated playa periods (the local LGM and Younger Dryas) with a sporadic or cessation
of riverine inflows. Alternatively, in this hyperarid environment, airborne material is a
permanent, vital input for the catchment depocenter. The minor variance of quartz and
plagioclase content implies that the aeolian activity that conveyed coarse-grained sediments
into the Orog Nuur catchment basin was quasi-constant through the late Quaternary.
Likewise, as demonstrated by robust multivariate statistics, in the context of the Eijina Basin,
there is no sharp variation of aeolian sands input through the late Quaternary (Yu et al., 2016),
albeit the LGM might have been subject to a slightly higher aeolian deflation in the arid
central Asia (Nilson and Lehmkuhl, 2001). This amount of airborne material was thus
incorporated into the sediment trap at a quasi-constant rate, in spite of the lacustrine setting,
119
playa, or other land surfaces. Thus, the sharp increase of Ca since the very beginning of the
Holocene seems not to have been caused solely by the quansi-constant aeolian activity.
From the onset of the Unit V, both hornblende and CaCO3 demonstrate a coeval abrupt
increase. This phenomenon is also documented in calcite and Ca (peak areas) (Fig. 6-3). The
distinct behavior of Ca in the Holocene sediments is also properly depicted in the biplot
against Al/Si (Fig. 6-5), as well as the scores plot revealed by robust multivariate statistics
(Fig. 6-4B). All of the evidence corroborates the theory that the past environment is not the
sole governing factor exerting influence on the sediment bulk-composition, and that
prominently different source lithotypes and/or higher authigenic productivity may have
existed before and after Termination I. This different provenance may be attributed to twofold
pathways given that the catchment basin is intimately linked to the higher catchment via the
Tuyn Gol: (i) in the stadial (Younger Dryas event) of the late glacial period, the glacial-
pluvial debris accumulated in the higher Khangai Mountains may not have been subject to
abrasion and transport into the Orog Nuur. Subsequently, immediately after Termination I,
due to climate amelioration-induced deglaciation and the hydrodynamically strengthened
riverine inflows, abrupt increases of clastic minerals were available for transport into the Orog
Nuur (Fig. 6-1B), resulting in a sharp increase of the Ca, calcite, and hornblende abundance in
the Holocene, as well as the distinct biplot pattern of Ca vs. Al/Si (Figs. 6-3 and 6-5).
Furthermore, this increased weathering and fluvial input is corroborated by the negative
values of Factor 4 (high terrigenous input) of the Holocene samples in the scores plot (Fig. 6-
4B) and the decreased Rb/Sr ratios of the Holocene samples (Fig. 6-3; Davies et al., 2015).
(ii) Due to the temperature amelioration and better moisture conditions, markedly intensified
chemical weathering (decrease of Rb/Sr) and denudation (increased mica, chlorite and
hornblende contents) occurred in the upper catchment of Orog Nuur, where the source
terranes were broadly occupied by felsic/alkaline and patchy mafic plutonic rocks (Fig. 6-1B
and 6-3). In addition, as suggested by Millot (1970), when hypersaline brines reach saturation,
alkaline earth carbonates will be the first precipitates followed by calcite and aragonite. Thus,
an immense amount of alkaline carbonates and subsequent authigenic calcite have been
generated from the felsic and alkaline precursors, causing a distinct alkaline environment
(higher authigenic productivity) in the Holocene. Thus, only the biplot of Ca vs. Al/Si has
rendered a sound and distinct picture of conditions of the Holocene relative to late Pleistocene
sediments.
120
Fig. 6-6. Schematic model of the integrated past environmental change, land surface
processes and provenance signals (carbonate geochemistry) of the Orog Nuur catchment over
the last ~50 ka. The eastern parts of Khangai Mountains (higher reach of the Orog Nuur
catchment) with altitudes between 3,500 m and 3,700 m asl. have no modern glaciers. More
details regarding glacial and vegetation developments in the catchment are given in
Lehmkuhl and Lang (2001), Rother et al. (2014), and Lehmkuhl et al. (2016). Distinct
geochemical signals for each phase also refer to the table in supplementary material of this
paper.
In summary, influences from the integrated past environment (weathering and land surface
processes) and provenance signals cannot be separately discerned in the arid context. They
more likely represent inherently intercorrelated mechanisms regarding the bulk-geochemistry
of the lacustrine sediments (Fig. 6-6).
121
6.5.4. Summary of coupled paleoenvironmental, weathering, catchment land surface
processes, and provenance signals over the past ~50 ka BP in the Orog Nuur catchment
The overall knowledge gained above has allowed gleaning of the hydro-geochemical
implications of the Orog Nuur water body, as well as the reconstruction of
paleoenvironmental conditions and provenance signals in the drainage catchment (Fig. 6-6).
6.5.4.1. Unit I (~50-~19 cal ka BP): shallow to lentic water body, moderate catchment
weathering
Ample proxy and modelling evidence illustrates that it was generally humid in arid
northwestern China over MIS 3 (Herzschuh, 2006; Yu et al., 2007). It has been suggested that
this may have been caused either by the strengthening of the Asian moisture-laden monsoon
or by a strengthened moisture supply by the westerlies (Yang and Scuderi, 2010). This
enhanced moisture supply is documented in the Orog Nuur sediment core by high amounts of
clay and silt, and is also indicated by a high abundance of the minerals mica and chlorite that
are fluvially transported to the lake. Factor 4 elements, plagioclase, and K-feldspar retain
generally high levels in Unit I, indicating allogenic fluvial input linked to adjacent source
lithotypes in the catchment (Fig. 6-6). On the other hand, however, several intercalated sand
layers with corresponding spikes in the C/Natomic ratio point to sporadic desiccation of the
water column and abrupt fluvial-induced allogenic terrestrial input. The depths of these sand
layers (playa phases) exhibit broad consistency with the spikes in the elemental variances and
the Al/Si ratio (Fig. 6-3). Apart from the sand layers, most phases in Unit I reveal a slightly
reducing environment as inferred from the Mn abundance (Fig. 6-3). A moderate weathering
rate is demonstrated by the largely higher values of the Rb/Sr ratios throughout Unit I. In
summary, Unit I developed in a humid environment with regular riverine inflows of the Tuyn
Gol. Throughout the time period of Unit I, the water body was generally shallow and
sporadically converted into playa conditions (Fig. 6-6). This generally humid phase in MIS 3
is corroborated by low dust supply in the northwestern Pacific pelagic sequences (Leinen,
1989; Nilson and Lehmkuhl, 2001).
6.5.4.2. Unit II (~19-~18 cal ka BP): playa phase and minor riverine inflow
This unit, related to the global LGM, is represented by a massive sand layer that marks an
abrupt deterioration of the hydro-environment in the catchment (Fig. 6-6). The Orog Nuur
was completely desiccated and changed to a playa environment, which served as an allogenic
122
dust sink with ephemeral alluvial/fluvial deposition. In a modern context, aeolian silts and
mobile dunes were generally accumulated in the (winter monsoon) downwind direction,
namely the southeastern section of the Orog Nuur (Lehmkuhl and Lang, 2001). The Factor 4
elements, mud clay, and fluvial clastic bearing minerals mica, chlorite, plagioclase, and
hornblende all exhibit drastically declining contents due to the virtual absence of argillaceous
sediments (Fig. 6-3). Conversely, allogenic K-feldspar displays an abrupt increase related to
the sharply increased contribution of feldspar-bearing sand. The C/Natomic ratios with broadly
greater values than 20 also suggest a more frequent input of allogenic matter. The slightly
reduced redox condition was broken down, as shown by extremely low concentrations of Mn
(Calvert and Pedersen, 2007; Wirth et al., 2013). The in situ weathered materials from the
higher catchment in the Khangai Mountains were preserved locally due to reduced fluvial
transport capacity, and thus were seldom transported into the Orog Nuur.
6.5.4.3. Unit III (~18-~13 cal ka BP): shallow saline lake, moderate weathering in higher
catchment
This period corresponds with the commencement of the last deglaciation in the southern
Mongolian Plateau. Climate amelioration after the LGM led to the melting of glaciers (Rother
et al., 2014) in the higher Khangai Mountains and resulted in a significantly raised amount of
riverine inflows into the Orog Nuur (Fig. 6-6; C/Natomic exhibits slightly higher values relative
to Unit I). The water body was instantly recovered to a state that is comparable with
hydrological conditions prior to the LGM. The relatively stagnant environment is also
demonstrated by high Mn abundance and low C/Natomic ratios (Fig. 6-3). The Factor 4
elements Si, Al, and Fe exhibit similar abundances relative to those in Unit I, suggesting
analogous hydro-geochemical and moderately higher catchment weathering conditions (Figs.
6-4B and 6-6). A slightly increased Cl abundance implies raised salinity of the water body in
contrast to Unit I (Sinha et al., 2006). In contrast, Factor 2 proxies Ca, calcite, and CaCO3 are
low compared to the older late Pleistocene units, indicating a broadly unchanged authigenic
condition within the lake system. Furthermore, similar Rb/Sr ratios relative to those in Unit I
also reflect a largely unchanged weathering intensity in the catchment.
6.5.4.4. Unit IV (~13-~11 cal ka BP): playa phase with slightly more riverine inflows
relative to LGM
This unit again, as in the LGM, is represented by a sand layer (Fig. 6-4B). It corresponds to a
climate deterioration episode associated with the late glacial Younger Dryas event. Although
123
the Orog Nuur system did not completely turn into a playa system as during the LGM (Unit
II; Fig. 6-4B), it experienced repeated desiccations giving rise to the deposition of coarse
sands brought in by fluvial and aeolian processes (Fig. 6-6). The sharp decrease in clay and
silt-clay is displayed by exceedingly low abundances of Fe, Mn and Co, whereas marked
fluctuations in C/Natomic ratios hint at the frequent occurrence of allogenic fluvial inputs into
the playa system (Fig. 6-3). In addition, the (i) sand layer, (ii) reduced run-off input, and (iii)
varved sediments altered to unvarved strata related to the Younger Dryas are also documented
in the nearby lacustrine sequence of Ulaan Nuur in the Valley of Gobi Lakes (Fig. 6-1A; Lee
et al., 2011), in the Lake Tana in northern Ethiopia (Lamb et al., 2007), and in the Lake
Mondsee in Europe (Lauterbach et al., 2011), respectively. These features presumably
characterize a benchmark lithofacies in the lacustrine sequences in the Gobi Desert of
Mongolia or even on a larger northern hemispheric scale. In particular, this YD event-related
Ca depletion with sharp boundaries at c. 11,500 and 12,500 cal a BP is also clearly recorded
in the varved lacustrine core from Lake Mondsee (Luterbach et al., 2011), albeit the
corresponding archive is not a sand layer as in this study in the desert realm.
6.5.4.5. Unit V (<~11 cal ka BP): lentic hypersaline lake with abruptly increased
terrigenous inputs and authigenic productivity
An abrupt recovery of lacustrine conditions marks the termination of the late glacial stage as a
chronological benchmark in the Orog Nuur catchment. This rapid increase of Ca abundance
linked to the ameliorated Holocene climate is also recorded in Lake Mondsee in the
northeastern Alps (Lauterbach et al., 2011). The granulometric composition is akin to that of
Units I and III with slightly higher clay and silt concentrations (Fig. 6-2; Al/Si ratio in Fig. 6-
3). The most remarkable feature of the Holocene phase is the amount of hornblende and
calcite corresponding to high Ca and CaCO3 concentrations that are significantly greater
relative to late Pleistocene units (Fig. 6-5). This feature suggests a considerably different
hydro-geochemical habitat associated with paleoclimatic amelioration. The characteristic
presence of carbonate indicates a predominant alkaline environment (higher Cl content) with
abundant moisture supply and raised authigenic productivity (Wünnemann et al., 2010). This
postulation is reinforced by the distinct assemblage of Ca in the biplot against Al/Si (Figs. 6-
4B and 6-5; Norman and De Deckker, 1990). Another reason for its occurrence, however, is
that the calcite may also result from its recrystallization from detrital precursors (neogenic
calcite; Pettijohn et al., 1973). In this case, more eroded clastic materials from the northern
felsic and alkaline source terranes were brought into the Orog Nuur (Figs. 6-1B and 6-6).
124
However, in terms of late Quaternary terrestrial (lacustrine) sediments, this diagenesis
(recrystallization) may only have exerted limited influence on the bulk-geochemistry relative
to the climate-induced calcite precipitation as well as allochthones input (Pettijohn, 1973; Yu
et al., 2016). Furthermore, the significantly increased input of weathering materials is also
demonstrated by the sharp increase of the Rb/Sr ratio (Fig. 6-3). In general, the higher
Holocene lake level is in agreement with that from Lehmkuhl and Lang (2001). In the Baikal
catchment further to the north (Fig. 6-1A), a wealth of palynological signals was assembled
and assessed by Tarasov et al. (2007), who revealed a broadly warm and humid early
Holocene as well as a deteriorated climate since the mid-Holocene. Nonetheless, in this study,
due to the loss of the uppermost 24 cm of sediments and a relatively high uncertainty in the
Holocene age in the Bayesian age model (Fig. 6-2), a feasible interpretation for the late
Holocene signals is difficult to construct. Accordingly, the lentic hypersaline habit proposed
here might be restrained to the early- to mid-Holocene period.
In summary, the distinct Holocene water body is attributed to (i) a more intensively weathered
felsic/alkaline material transported from the higher catchment into the Orog Nuur depocenter,
and (ii) sharply increased authigenic productivity of the alkaline environment thereafter.
6.6. Conclusions
We present a continuous, high-resolution elemental record attained in the lacustrine sequence
of Orog Nuur, southern Mongolia. An integrated paleoenvironmental and provenance history
in the Gobi Desert that trace back to the MIS 3 are outlined for the first time.
To constrain the data quality, elements with high error margins relative to measured peak
areas, and those elements/proxies under a significance level during the robust multivariate
statistics are ruled out for further implications. As determined by robust multivariate statistics,
the bulk-geochemistry of the Orog Nuur core sediments are governed by Factor 1 (grain-size
composition), Factor 2 (authigenic productivity in the saline/evaporitic environment: Ca, Cl,
CaCO3, Factor 3 (allochthonous organic material input: TOC, C/Natomic, and Factor 4 (fluvial
terrigenous input, as well as quasi-constant aeolian input through the late Quaternary period:
Al, Si, K, Ti, Fe, chlorite, and hornblende). As inferred from the biplot of Ca vs. Al/Si,
disparate source lithotypes along with authigenic productivity existed before and after
Termination I. In contrast to the late Pleistocene, the Holocene was dominated by a distinctly
high productivity alkaline environment due to the increased hydrodynamic strength of riverine
inflow and intensified source rock weathering/erosion in the upper catchments of Orog Nuur.
125
In order to gain a better understanding of the bulk-geochemistry of lake sediments, the
coupled provenance and environmental signatures, such as weathering and land surface
processes in the catchment, need to be systematically discerned. Thus, considering the bulk-
geochemistry of lacustrine sediments, paleoclimate would not be the sole governing factor;
the coupled alteration of precursor rocks and accompanying decomposition / denudation
intensity, as well as the transportation process may exert pivotal influences.
In the arid realm of Gobi Desert of Mongolia, two coarse sand layers corresponding to the
LGM and Younger Dryas are present. In the Gobi Desert, these two layers provide a potential
opportunity to act as chronological benchmarks. However, more investigation needs to be
carried out to test the reliability of these beds on larger spatial scales and their synchrony in
time.
Table 6-S1 Synoptic description of the coupled paleoenvironmental and provenance
signatures during the past ~50 ka BP as inferred from the lacustrine sequence of Orog Nuur.
A schematic model comprising these factors is proposed in Fig. 6-6 in the main text.
Lithostrati
graphic
units
Correspondi
ng ages (cal
ka BP)
Water column and
climatic interpretations
Broad source lithotypes and
land surface processes
Distinct bulk-geochemistry
I ~50-~19 shallow to lentic water
body
Weathering of felsic and few
mafic plutonic rocks
High S, Al, and Si; low Cl, Ca,
calcite and hornblende
II ~19-~18 arid playa phase Intensified aeolian sands
deposited in fluvial coarse-
grained sediments
High K-Feldspar, C/N ratio;
low terrestrial elements, mica,
chlorite, and calcite
III ~18-~13 shallow saline lake Felsic and few mafic plutonic
rocks similar like phase I
High S and Co; low Ca, calcite
and hornblende
IV ~13-~11 arid playa phase Intensified aeolian sands
input and seldom fluvial
activity
High C/N ratio; low terrestrial
elements and Ca/CaCO3
V <~11 lentic & hypersaline water
body
alkaline, felsic, and few mafic
plutonic rocks, together with
intensive erosion of bedrocks
High Ca, Cl, calcite, mica,
chlorite and hornblende; low S,
quartz, plagioclase, and K-
feldspar
126
Fig. 6-S1. Dispersion plots of the major and trace element concentrations (peak areas)
according to their stratigraphic units. Numbers of observations for each unit are marked on
the upmost axis. The median values are linked with dash lines, while the upper and lower
quartiles are marked as error bars.
127
7. Synthesis: Paleoclimatic implications from late Quaternary terrestrial archives in the
Gobi Desert
This dissertation presents results from the multidisciplinary study on terrestrial archives
embracing aeolian, fluvial, alluvial and lacustrine sediments in the arid realm, and their
corresponding thermal and moisture implications. To close the loop of this dissertation, main
thermal and moisture history of the Gobi Desert of Mongolia is illustrated in Fig. 7-1. The
core part is summarized as follows, reflecting the significant findings in this research.
Fig. 7-1: Synoptic compilation of hydrologic, vegetation and glacial history of the Orog Nuur
catchment over the last ~50 ka. Playa & dune phase is recovered from the granulometric and
lithostratigraphic characteristics of the core ONW II. Likewise, this late Glacial high lake
levels are also recorded in the Ejina Basin as lacustrine facies.
7.1. Bulk-geochemistry of different terrestrial archives in the arid realm and their
corresponding implications for the paleoenvironmental, pedogenesis and diagenesis
processes
A practical strategy is presented to discriminate sediment archive properties and thereafter
sequence the controlling factors of sedimentary processes. The considered records of northern
Ejina Basin can be discriminated into three broad lithological units: basal aeolian strata,
lacustrine strata and the uppermost poorly-sorted mixture of coarse sand and gravels.
128
Elemental characteristics in conjunction with the granulometric composition in different
sediment archives in the northern Ejina Basin are obtained. Aeolian sands have high contents
of Zr, Hf, Ba and Si. Especially Hf can be regarded as good indicator to discriminate the
coarse sand proportion. Sandy loess has high contents of Ca and Sr which both exhibit broad
correlations with medium to coarse silt proportions. Lacustrine clay has high contents of
felsic, ferromagnesian and mica source elements. Fluvial sands have distinctly high contents
of Mg, Cl and Na which are enriched in evaporate minerals. Alluvial gravels have especially
high contents of Cr which may originate from nearby Cr-rich bedrock.
Multivariate statistical methods applied to geochemical compositions is a useful tool to
discriminate archive types in our case. Considering the suite of late Quaternary sediments in
the arid realm, temporal variation of the bulk-geochemistry can be well explained by four
semi-quantified sediment components: (weak-) weathering intensity, silicate-bearing mineral
abundance, saline / alkaline influence of sediments, and the quasi-constant aeolian input into
the arid endorheic basin system. In contrast, pedogenesis and diagenesis exert only a limited
influence.
7.2. Sedimentological, palynological and ostracod studies of the lacustrine sediments and
their references to the paleohydrological and vegetation history
A multidisciplinary investigation is conducted on a 13.35 m lacustrine core retrieved from
Orog Nuur, in the Gobi Desert of Mongolia. Methods embracing sedimentological,
geochemical, palynological and ostracod studies combined with sets of dated terrace ridges
and moraines were conducted to illustrate the vegetation development, hydrologic and
paleoglaciation history during the last ~ 50 ka. For the first time, in the Gobi Desert, semi-
quantified moisture and thermal sequences that track back to the MIS 3 are presented.
In Gobi Desert of Mongolia, the MIS 3 experienced sufficient moisture supply in particular
between ~36 ka and ~24 ka; MIS 2 was subjected to cool temperature and moisture-deficient,
which was interrupted by two exceedingly cold and dry playa phases related to the LGM and
YD event; The early Holocene exhibited ameliorated climatic condition characterized by
higher lake levels. In addition, a sharp transition of Termination I is illuminated by
palynological and geochemical imprints. Lower area of the Orog Nuur catchment was
dominated by Artemisia steppe community in the late Pleistocene and altered to
Chenopodiaceae desert steppe in the Holocene. Water body in the Holocene appears to be a
129
distinct alkaline environment which was subjected to frequently allogenic input and
disturbance of the late Pleistocene anoxic states.
The main humid pulse in MIS 3 might have been the main driving mechanism for the MIS 3
glacial advance, while the pronounced low temperature in the higher elevated catchment in
the eastern Khangai Mountains is presumably the forcing factor for the LGM glacial advance.
The early Holocene in the Gobi Desert experienced the other humid pulse, which was
concurrent with the lacustrine condition and the degradation of the permafrost features as well
as the glacial retreat. On the other hand, four arid playa phases (~47 ka, ~37 ka, ~19 ka and
~13-~11 ka) were determined, of which the latter two sand layers (i.e., the LGM, YD event,
respectively) recorded in the Orog Nuur may provide an opportunity to be labelled as
chronological benchmarks for other lacustrine sequences in the Gobi Desert of Mongolia.
Nonetheless, further investigations still need to be carried out to test its reliability in a larger
spatial scale.
In the central to southern Mongolia, the late Quaternary moisture and thermal history may be
modulated, if not controlled, by coupled atmospheric components embracing both Westerlies
and the propagation of the East Asian Summer Monsoon into the Asian interior, albeit more
details with respect to the quantified contribution from these systems remain an open
question.
7.3. Geochemical imprints of the lacustrine sediments and integrated
paleoenvironmental and provenance implications
Based on a continuous, high-resolution elemental records attained in the lacustrine sequence
of Orog Nuur, Gobi Desert of Mongolia, the coupled paleoenvironmental and provenance
history are outlined. Due to the predominant sediments of mud- to siltstone, Al and Si display
broadly identical pattern in the lake sediments. Ca behaviors may be ascribed to the
authigenic calcite abundance. As equally applicable to pelagic sediments, Mn and Co may act
as indicator for the redox condition in lacustrine realm. On the other hand, owing to the short
burial time and weak diagenetic influence, Fe is not an indicator to the diagenetic processes.
Likewise, Zr may be associated to fluvial clastic in relation to the lithotypes but not
necessarily linked to the aeolian sands concentration as in the pelagic realm. Furthermore, S
in lake sediments may denote the redox condition and K is more likely linked to the K-
feldspar which is associated with the allogenic fluvial inputs.
130
The two sand laminations corresponding to the LGM and YD are dominated by coarse sands.
In the Gobi Desert of southern Mongolia, these two laminations provide a potential
opportunity to be regarded as chronological benchmarks. However, more investigation needs
to be conducted to test its reliability in larger spatial scales.
As inferred from the biplot between Ca and Al/Si, disparate source lithotypes may exist
before and after the Termination I. The Holocene appears to be a distinct alkaline
environment relative to the late Pleistocene. This may be ascribed to either strengthened
hydrodynamic strength of the riverine inflows and / or intensified source rocks erosion in the
upper catchments of Orog Nuur. In order to gain a better understanding of the bulk-
geochemistry of lake sediments, the coupled provenance and environmental signatures need
to be properly discerned. On the other hand, in arid realm as Gobi Desert of Mongolia, sands
may exert a considerable influence on the bulk-geochemistry of lacustrine sediments.
In summary, considering the bulk-geochemistry of lacustrine sediments, paleoclimate would
not be the solely governing factor, the coupled alteration of precursor rocks and
decomposition intensity may exert pivotal influences.
7.4. Outlook
For the upcoming decades, several pivotal but challenging tasks need to be carried out to
better decipher the paleoclimate signals and controlling atmospheric circulations in the arid
central Asia, on perspectives of both terrestrial and pelagic archives. A fundamental step is to
refine the understandings concerning the proxies and their corresponding paleoenvironmental
implications. The tasks are assembled as follows:
(1) As the purposes of the paleoclimatologist are primarily high resolution and longer time
spanning of the repository, it is therefore indispensable to take part in IODP / ECORD
excursion in e.g., NW Pacific, retrieving continuous, high resolution and well constrained
chronological framework pelagic sequences;
(2) Get innovative methods, e.g., neodymium or other isotopes signals incorporated in the
pelagic sediments, to discriminate Westerlies signals from EASM, and build thereby
robust Westerlies Intensity indices. Eventually, compare with our published arid central
Asia data in this dissertation. Thereafter, it is possible to define and decipher the moisture
provenance in the Gobi Desert of Mongolia;
131
(3) Investigate long time scale lacustrine core retrieved in southern Mongolia, from where
great scarcity of paleoenvironmental repository exists. Alternatively, terrestrial drilling
project (e.g., lacustrine, loess-paleosol sequences) could be carried out underneath the
pathway of the mid-latitude Westerlies. Compared to the pelagic sequences,
environmental interpretations concerning those elements such as trace and REE elements
abundance as well as non-conventional isotopes signals in lacustrine realm are less studied
and understood. A time spanning of greater than the late glacial period is in urgent need in
order to gain a comprehensive understanding of the kinetics of central to eastern Asian
paleoclimate patterns;
(4) Gain robust and quantitatively defined indices for thermal and moistures signals.
Promising proxies are geobiology (pollen / ostracod / diatom), geochemistry (elements,
minerals and non-conventional isotopes) and geophysics (paleomagnetic), of which the
paleomagnetic is of special importance because of its application of refinement of the
surface sediments’ age model and thereafter the estimation of reservoir effect from the
radiocarbon determined age model;
(5) In particular, the geologic repository may not illustrate complete consistency with the
numerical simulation results (e.g., Jiang et al., 2012). It is therefore indispensable to
provide high resolution, (semi-) quantified proxy sequence as parameters for the modelers.
In turn, the high resolution simulation results should be taken into account in trying to
better understand the atmospheric patterns and underlying mechanisms of the
paleoclimate changes.
The fulfillment of above points will largely fill the knowledge gaps in the arid central Asia
and therefore benefit the paleoclimatological communities.
132
References
Aitken, M.J., 1998. An Introduction to Optical Dating. Oxford University Press, Oxford, pp.
43-44.
Amorosi, A., Centineo, M.C., Dinelli, E., Lucchini, F. Tateo, F., 2002. Geochemical and
mineralogical variations as indicators of provenance changes in Late Quaternary
deposits of SE Po Plain. Sedimentary Geology 151, 273-292.
An, C.B., Chen, F.H., Barton, L., 2008. Holocene environmental changes in Mongolia: A
review. Global and Planetary Changes 63, 283-289.
An, C.B., Zhao, J.J., Tao, S.C., Lv, Y.B., Dong, W.M., Li, H., Jin, M., Wang, Z.L., 2011.
Dust variation recorded by lacustrine sediments from arid Central Asia since ~15 cal ka
BP and its implication for atmospheric circulation. Quaternary Research 75, 566-573.
An, Z.S., Li, L., Burr, G.S., Song, Y.G., Yan, L.B., Chang, H., Sun, Y.B., Cai, Y.J., Shi, Z.G.,
Xu, H., Zhao, H.L., Zhou, W.J., 2014. Introduction. In: An, Z.S., (Eds.). Late Cenozoic
Climate Change in Asia. Developments in Palaeoenvironmental Research 16, Springer,
Dordrecht, pp. 1-22.
An, Z.S., Porter, S.C., Kutzbach, J.E., Wu, X.H., Wang, S.M., Liu, X.D., Li, X.Q., Zhou,
W.J., 2000. Asynchronous Holocene optimum of the East Asian Monsoon. Quaternary
Science Reviews 19, 743-762.
Anadon, P., Utrilla, R., Julià, R., 1994. Palaeoenvironmental reconstruction of a Pleistocene
lacustrine sequence from faunal assemblages and ostracode shell geochemistry, Baza
Basin, SE Spain. Palaeogeography, Palaeoclimatology, Palaeoecology 111, 191-205.
Arz, H.W., Lamy, F., Pätzold, J., Müller, P.J., Prins, M., 2003. Mediterranean moisture source
for an Early-Holocene humid period in the Northern Red Sea. Science 300, 118-121.
Baljinnaym, I., Bayasgalan, A., Brorisov, B.A., Cisternas, A., Dem'yanovich, M.G.,
Ganbaatar, L., Kochetkov, V.M., Kurushin, R.A., Molnar, P., Philip, H., Vashchilov,
Y.Y., 1993. Ruptures of major earthquakes and active deformation in Mongolia and its
surroundings. Geology Society of America Memoirs 181, 26-52.
Barry, R.G., Chorley, R.J., 2009. Atmosphere, Weather and Climate. Routledge, Abingdon,
pp. 127-161.
Bayasgalan, A., Jackson, J., Ritz, J.-F., Carretier, S., 1999. “Forebergs”, flower structures, and
the development of large intra continental strike-slip faults: the Gurvan Bogd fault
system in Mongolia. Journal of Structural Geology 21, 1285-1302.
Becken, M., Hölz, S., Fiedler-Volmer, R., Hartmann, K., Wünnemann, B., Burkhardt, H.,
2007. Electrical resistivity image of the Jingsutu Graben at the NE margin of the Ejina
Basin (NW China) and implications for the basin development. Geophysical Research
Letters 34, doi: 10.1029/2007GL029412.
Benn, D.I., Owen, L.A., 1998. The role of the Indian Summer Monsoon and the mid-latitude
weterlies in Himalayan glaciation: review and speculative discussion. Journal of the
Geological Society, London 155, 353-363.
133
Berger, A., Loutre, M.F., 1991. Insolation values for the climate of the last 10 million years.
Quaternary Science Reviews 10, 297-317.
Bertrand, S., Hughen, K., Giosan, L., 2015. Limited Influence of Sediment Grain Size on
Elemental XRF Core Scanner Measurements. In: Croudace, I.W., Guy Rothwell, R.,
(eds) Micro-XRF Studies of Sediment Cores. Developments in Paleoenvironmental
Research 17, pp 473-490.
Bhatia, M.R., 1983. Plate tectonics and geochemical composition of sandstones. The Journal
of Geology 91, 611-627.
Blott, S.J., Pye, K., 2012. Particle size scales and classification of sediment types based on
particle size distributions: Review and recommended procedures. Sedimentology 59,
2071-2096.
Bond, G., Broecker, W., Johnsen, S., McManus, J., Labeie, L., Jouzel, J., Bonani, G., 1993.
Correlations between climate records from North Atlantic sediments and Greenland ice.
Nature 365, 143-147.
Bøtter-Jensen, L., Thomsen, K.J., Jain, M., 2010. Review of optically stimulated
luminescence (OSL) instrumental developments for retrospective dosimetry. Radiation
Measurements 45, 253-257.
Boyle, J.F., 2001. Inorganic geochemical methods in palaeolimnology. In: Last, W.M., Smol,
J.P., (Eds.). Tracking Environmental Change Using Lake Sediments Volume 2: Physical
and Geochemical Methods. Developments in Paleoenvironmental Research 2, pp. 83-
130.
Boyle, E.A., Keigwin, L., 1987. North Atlantic thermohaline circulation during the past
20,000 years linked to high-latitude surface temperature. Nature 330, 35-40.
Bridge, J.S., Demicco, R.V., 2008. Earth surface processes, landforms and sediment deposits.
Cambridge: Cambridge University Press, p 61.
Broccoli, A.J., Dahl, K.A., Stouffer, R.J., 2006. Response of the ITCZ to Northern
Hemisphere cooling. Geophysical Research Letters 33, L01702, doi:
10.1029/2005/2005GL024546.
Broecker, W.S., 1994. Massive iceberg discharges as triggers for global climate change.
Nature 372, 421-424.
Brooks, S.J., 2006, Fossil midges (Diptera: Chironomidae) as palaeoclimatic indicators for the
Eurasian region. Quaternary Science Reviews 25, 1894-1910.
Buggle, B., Glaser, B., Zöller, L., Hambach, U., Marković, S., Glaser, I., Gerasimenko, N.,
2008. Geochemical characterization and origin of Southeastern and Eastern European
loess (Serbia, Romania, Ukraine). Quaternary Science Reviews 27, 1058-1075.
Bush, A.B.G., 2004. Modelling of Late Quaternary climate over Asia: a synthesis. Boreas 33,
155-163.
Calvert, S.E., Pedersen, T.F., 2007. Elemental proxies for palaeoclimatic and
palaeoceanographic variability in marine sediments: Interpretation and application. In:
134
Hillaire-Marcel, C., De Vernal., A., (Eds.). Proxies in late Cenozoic paleoceanography.
Developments in Marine Geology 1, 567-625.
Chen, C.-T. A., Lan, H.-C., Lou, J.-Y., Chen, Y.-C., 2003. The dry Holocene megathermal in
Inner Mongolia. Palaeogeography, Palaeoclimatology, Palaeoecology 193, 181-200.
Chen, F.H., Dong, G.H., Zhang, D.J., Liu, X.Y., Jia, X., An, C.B., Ma, M.M., Xie, Y.W.,
Barton, L., Ren, X.Y., Zhao, Z.J., Wu, X.H., Jones, M.K., 2015. Agriculture facilitated
permanent human occupation of the Tibetan Plateau after 3600 B.P. Science 347, 248-
250.
Chen, F.H., Fan, Y.X., Chun, X., Madsen, D.B., Oviatt, C.G., Zhao, H., Yang, L.P., Sun, Y.,
2008a. Preliminary research on Megalake Jilantai-Hetao in the arid areas of China
during the Late Quaternary. Chinese Science Bulletin 53, 1725-1739.
Chen, F.H., Yu, Z.C., Yang, M.L., Ito, E., Wang, S.M., Madsen, D.B., Huang, X.Z., Zhao, Y.,
Sato, T., Birks, H.J.B., Bommer, I., Chen, J.H., An, C.B., Wünnemann, B., 2008b.
Holocene moisture evolution in arid central Asia and its out-of phase relationship with
Asian monsoon history. Quaternary Science Reviews 27, 351-364.
Chen, H.F., Song, S.R., Lee, T.Q., Löwemark, L., Chi, Z.Q., Wang, Y., Hong, E., 2010. A
multiproxy lake record from Inner Mongolia displays a late Holocene teleconnection
between Central Asian and North Atlantic climates. Quaternary International 227, 170-
182.
Chen, J., Li, G.J., 2011. Geochemical studies on the source region of Asian dust. Science
China Earth Sciences 54, 1279-1301.
Chen, J.H., 2009. Moisture variability over the last millennium recorded by chironomids from
lacustrine sediments in arid northwestern China. Dissertation to Lanzhou University.
Cheng, H., Spötl, C., Breitenbach, S.F.M., Sinha, A., Wassenburg, J.A., Jochum, K.P.,
Scholz, D., Li, X.L., Yi, L., Peng, Y.B., Lv, Y.B., Zhang, P.Z., Votintseva, A., Loginov,
V., Ning, Y.F., Kathayat, G., Edwards, R.L., 2016. Climate variations of Central Asia
on orbital to millennial timescales. Scientific Reports 6, 36975, doi: 10.1038/srep36975.
Chiang, J.C.H., Fung, I.Y., Wu, C.-H., Cai, Y.J., Edman, J.P., Liu, Y.W., Day J.A.,
Bhattacharya, T., Mondal, Y., Labrousse, C.A., 2015. Role of seasonal transitions and
westerly jets in East Asian paleoclimate. Quaternary Science Reviews 108, 111-129.
Chilingar, G.V., Zenger, D.H., Bissell, H.J., Wolf, K.H., 1979. Dolomites and dolomitization.
In: Larsen, G., Chilingar, G.V., (Eds.). Diagenesis in Sediments and Sedimentary
Rocks. Developments in Sedimentology 25A, pp. 428-536.
Clark, P.U., Shakun, J.D., Baker, P.A., Bartlein, P.J., Brewer, S., Brook, E., Carlson, A.E.,
Cheng, H., Kaufman, D.S., Liu, Z.Y., Marchitto, T.M., Mix, A.C., Morrill, C., Otto-
Bliesner, B.L., Pahnke, K., Russell, J.M., Whitlock, C., Adkins, J.F., Blois, J.L., Clark,
J., Colman, S.M., Curry, W.B., Flower, B.P., He, F., Johnson, T.C., Lynch-Stieglitz, J.,
Markgraf, V., McManus, J., Mitrovica, J.X., Moreno, P.I., Williams, J.W., 2012. Global
climate evolution during the last deglaciation. Proceedings of the National Academy of
Sciences 109, doi: 10.1073/pnas.1116619109.
135
Colman, S.M., Yu, S.Y., An, Z.S., Shen, J., Henderson, A.C.G., 2007. Late Cenozoic climate
changes in China’s western interior: a review of research on Lake Qinghai and
comparison with other records. Quaternary Science Reviews 26, 2281-2300.
Conroy, J.L., Restrepo, A., Overpeck, J.T., Steinitz-Kannan, M., Cole, J.E., Bush, M.B.,
Colinvaux, P.A., 2009. Unprecedented recent warming of surface temperatures in the
eastern tropical Pacific Ocean. Nature Geoscience 2, 46-50.
Costa, K.M., Russel, J.M., Vogel, H., Bijaksana, S., 2014. Hydrological connectivity and
mixing of Lake Towuti, Indonesia in response to paleoclimatic changes over the last
60,000 years. Palaeogeography Palaeoclimatology Palaeoecology 417, 467-475.
Cunningham,W.D., 2005. Active intracontinental transpressional mountain building in the
Mongolian Altai: Defining a new class of orogeny. Earth and Planetary Science Letters
240, 436-444.
Cunningham, W.D., 2013. Mountain building processes in intracontinental oblique
deformation belts: Lessons from the Gobi Corridor, Central Asia. Journal of Structural
Geology 46, 255-282.
Cunningham, W.D., Windley B.F., Dorjnamjaa, D., Badamgarov, J., Saandar, M., 1996. Late
Cenozoic transpression in southwestern Mongolia and the Gobi Altai-Tien Shan
connection. Earth and Planetary Science Letters 140, 67-81.
Cunningham, W.D., Windley, B.F., Owen, L.A., Barry, T., Dorjnamjaa, D., Badamagarav, J.,
1997. Geometry and style of partitioned deformation within a late Cenozoic
transpressional zone in the eastern Gobi Altai Mountains, Mongolia. Tectonophysics
277, 285-306.
Dansgaard, W., Johnsen, S.J., Clausen, H.B., Dahl-Jensen, D., Gundestrup, N.S., Hammer,
C.U., Hvldberg, C.S., Steffensen, J.P., Sveinbjörnsdottir, A.E., Jouzel, J., Bond, G.,
1993. Evidence for general instability of past climate from a 250-k ice-core record.
Nature 364, 218-220.
Dansgaard, W., White, J.W.C., Johnsen, S.J., 1989. The abrupt termination of the Younger
Dryas climate event. Nature 339, 532-534.
Dapples, E.C., 1979. Silica as an agent in diagenesis. In: Larsen, G., Chilingar, G.V., (Eds.).
Diagenesis in Sediments and Sedimentary Rocks. Developments in Sedimentology 25A,
pp. 99-142.
Davies, S.J., Lamb, H.F., Roberts, S.J., 2015. Micro-XRF core scanning in palaeolimnology:
recent developments. In: Croudace, I.W., Guy Rothwell, R., (Eds.). Micro-XRF Studies
of Sediment Cores. Developments in Paleoenvironmental Research 17, pp. 189-226.
Demske, D., Heumann, G., Granoszewski, W., Nita, M., Mamakowa, K., Tarasov, P.E.,
Oberhänsli, H., 2005. Late glacial and Holocene vegetation and regional climate
variability evidenced in high-resolution pollen records from Lake Baikal. Global and
Planetary Change 46, 255-279.
Derbyshire, E., Meng, X.M., Kemp, R.A., 1998. Provenance, transport and characteristics of
modern aeolian dust in western Gansu Province, China, and interpretation of the
Quaternary loess record. Journal of Arid Environments 39, 497-516.
136
Dietze, E., Maussion, F., Ahlborn, M., Diekmann, B., Hartmann, K., Henkel, K., Kasper, T.,
Lockot, G., Opitz, S., Haberzettl, T., 2014. Sediment transport processes across the
Tibetan Plateau inferred from robust grain-size end members in lake sediments. Climate
of the Past 10, 91-106.
Ding, Z.L., Liu, T.S., Rutter, N.W., Yu, Z.W., Guo, Z.T., 1995. Ice-volume forcing of East
Asian Winter Monsoon variations in the past 800,000 years. Quaternary Research 44,
149-159.
Divis, A.F., Anne McKenzie, J., 1975. Experimental authigenesis of phyllosilicates from
feldspathic sands. Sedimentology 22, 147-155.
Doberschütz, S., Frenzel, P., Haberzettl, T., Kasper, T., Wang, J.B., Zhu, L.P., Daut, G.,
Schwalb, A., Mäusbacher, R., 2013. Monsoonal forcing of Holocene
paleoenvironmental change on the central Tibetan Plateau using a sediment record from
Lake Nam Co (Xizang, China). Journal of Paleolimnology 51, 253-266.
Dorofeyuk, N.I., Tarasov, P.E., 1998. Vegetation and lake levels in Northern Mongolia in last
12,500 years as indicated by data of pollen and diatom analyses. Stratigraphy and
Geological Correlation 6, 70-83.
Duce, R.A., Unni, C.K., Ray, B.J., Prospero, J.M., Merrill, J.T., 1980. Long-range
atmospheric transport of soil dust from Asia to the tropical North Pacific: Temporal
variability. Science 209, 1522-1524.
Dulski, P., Brauer, A., Mangili, C., 2015. Combined µ-XRF and microfacies techniques for
lake sediment analyses. In: Croudace, I.W., Guy Rothwell, R., (eds) Micro-XRF Studies
of Sediment Cores. Developments in Paleoenvironmental Research 17, pp 325-349.
Egozcue, J.J., Pawlowsky-Clahn, V., Mateu-Figueras, G., Barceló-Vidal, C., 2003. Isometric
logratio transformations for compositional data analysis. Mathematical Geosciences 35,
279-230.
Eichler, A., Olivier, S., Henderson, K., Laube, A., Beer, J., Papina, T., Gäggeler, H.W.,
Schwikowski, M., 2009. Temperature response in the Altai region lags solar forcing.
Geophysical Research Letters 36, L01808, doi: 10.1029/2008GL035930.
Erdtman, G., 1960. The acetolysis method. Svensk Botanisk Tidskrift 54, 564-564.
Fedotov, A.P., Chebykin, E.P., Yu, S.M., Vorobyova, S.S., Yu, O.E., Golobokova, L.P.,
Pogodaeva, T.V., Zheleznyakova, T.O., Grachev, M.A., Tomurhuu, D., Oyunchimeg,
Ts., Narantsetseg, Ts., Tomurtogoo, O., Dolgikh, P.T., Arsenyuk, M.I., De Batist, M.,
2004. Changes in the volume and salinity of Lake Khubsugul (Mongolia) in response to
global climate changes in the upper Pleistocene and the Holocene. Palaeogeography,
Palaeoclimatology, Palaeoecology 209, 245-257.
Fedotov, A.P., Phedorin, M.A., De Batist, M., Ziborova, G.A., Yu, K.A., Yu., S.M.,
Matasova, G.G., Khabuev, A.V., Kugakolov, S.A., Rodyakin, S.V., Krapivina, S.M.,
Pouls, T., 2008. A 450-ka long record of glaciation in Northern Mongolia based on
studies at Lake Khubsugul: high-resolution reflection seismic data and grain-size
variations in cored sediments. Journal of Paleolimnology 39, 335-348.
137
Felauer, T., 2011. Jungquartäre Landschafts und klimagschichte der Südmongolei.
Dissertation zu Rheinishch-Westfälischen Technischen Hochshule Aachen.
Felauer, T., Schlütz, F., Murad, W., Mischke, S., Lehmkuhl, F., 2012. Late Quaternary
climate and landscape evolution in arid Central Asia: A multiproxy study of lake
archive Bayan Tohomin Nuur, Gobi desert, southern Mongolia. Journal of Asian Earth
Science 48, 125-135.
Feng, Z.D., Chen, F.H., Tang, L.Y., Kang, J.C., 1998. East Asian monsoon climates and Gobi
dynamics in marine isotope stages 4 and 3. Catena 33, 29-46.
Feng, Z.D., Wang, W.G., Guo, L.L., Khosbayar, P., Narantsetseg, T., Jull, A.J.T., An, C.B.,
Li, X.Q., Zhang, H.C., Ma, Y.Z., 2005. Lacustrine and eolian records of Holocene
climate changes in the Mongolian Plateau: preliminary results. Quaternary
International 136, 25-32.
Feng, Z.D., Zhai, X.W., Ma, Y.Z., Huang, X.Z., Wang, W.G., Zhang, H.C., Khosbayar, P.,
Narantsetseg, T., Liu, K.-B., Rutter, N.W., 2007. Eolian environmental changes in the
Northern Mongolian Plateau during the past ~35,000. Palaeogeography,
Palaeoclimatology, Palaeoecology 245, 505-517.
Filzmoser, P., Hron, K., Reimann, C., Garrett, R., 2009. Robust factor analysis for
compositional data. Computers & Geosciences 35, 1854-1861.
Fitzsimmons, K.E., Magee, J.W., Amos, K.J., 2009. Characterization of aeolian sediments
from the Strzelecki and Tirari Deserts, Australia: Implications for reconstructing
palaeoenvironmental conditions. Sedimentary Geology 218, 61-73.
Fleitmann, D., Burns, S.J., Mudelsee, M., Nef, U., Kramers, J., Mangini, A., Matter, A., 2003.
Holocene forcing of the Indian Monsoon recorded in a stalagmite from southern Oman.
Science 300, 1737-1739.
Folk, R.L., 1966. A review of grain-size parameters. Sedimentology 6, 73-93.
Forman, S.L., Pierson, J., Gómez, J., Brigham-Grette, J., Nowaczyk, N.R., Melles, M., 2007.
Luminescence geochronology for sediments from Lake Elgygytgyn, northeast Siberia,
Russia: constraining the timing of paleoenvironmental events for the past 200 ka.
Journal of Paleolimnology 37, 77-88.
Fowell, S.J., Hansen, B.C.S., Peck, J.A., Khosbayer, P., Ganbold, E., 2003. Mid to Late
Holocene climate evolution of the Lake Telmen Basin, north central Mongolia, based on
palynological data. Quaternary Research 59, 353-363.
Fumiko Watanabe, N., Watanabe, T., Kakegawa, T., Minoura, K., Imai, A., Fagel, N.,
Horiuchi, K., Nakamura, T., Kawai, T., 2014. Biological nitrate utilization in south
Siberian lakes (Baikal and Hovsgol) during the Last Glacial period: the influence of
climate change on primary productivity. Quaternary Science Reviews 90, 69-79.
Fralick, P.W., Kronberg, B.I., 1997. Geochemical discrimination of clastic sedimentary rock
sources. Sedimentary Geology 113, 111-124.
138
Franklin, S.B., Gibson, D.J., Robertson, P.A., Pohlmann, J.T., Fralish, J.S., 1995. Parallel
analysis: a method for determining significant principal components. Journal of
Vegetation Science 6, 99-106.
Gallet, S., Jahn, B., Van Vliet-Lanoë, B., Dia, A., Rossello, E., 1998. Loess geochemistry and
its implications for particle origin and composition of the upper continental crust. Earth
Planetary Science Letters 156, 157-172.
Ganning, B., 1971. On the ecology of Hetericyoris salinus, H. incongruens and Cypridopsis
aculeate (Crustacea: Ostracoda) from Baltic brackish-water rock pools. Marine Biology
8, 271-279.
Garzanti, E., Andò, S., France-Lanord, C., Vezzoli, G., 2009. Grain-size dependence of
sediment composition and environmental bias in provenance studies. Earth Planetary
Science Letters 277, 422-432.
Gillespie, A.R., Burke, R.M., Komatsu, G., Bayasgalan, A., 2008. Late Pleistocene glaciers in
Darhad Basin, northern Mongolia. Quaternary Research 69, 169-187.
Grunert, J., Lehmkuhl, F., Walther, M., 2000. Paleoclimatic evolution of the Uvs Nuur basin
and adjacent areas (western Mongolia). Quaternary International 65/66, 171-192.
Grunert, J., Stolz, C., Hempelmann, N., Hilgers, A., Hülle, D., Lehmkuhl, F., Felauer, T.,
Dasch, D., 2009. The evolution of small lake basins in the Gobi Desert in Mongolia.
Quaternary Sciences 29, 678-686.
Guérin, G., Mercier, N., Adamiec, G., 2011. Dose-rate conversion factors: update. Ancient TL
29, 5-8.
Gunin, P.D., Vostokova, E.A., Dorofeyuk, N.I., Tarasov, P.E., Black, C.C., 1999. Vegetation
dynamics of Mongolia. Geobotany 26, 233-238.
Guo, Y.J., Li, B.S., Wen, X.H., Wang, F.N., Niu, D.F., Shia, Y.J., Guo, Y.H., Jiang, S.P., Hu,
G.G., 2013. Holocene climate variation determined from rubidium and strontium
contents and ratios of sediments collected from the Badain Jaran Desert, Inner
Mongolia, China. Chemie der Erde-Geochemistry, doi: 10.1016/j.chemer.2013.09.001.
Gupta, A.K., Anderson, D.M., Overpeck J.T., 2003. Abrupt changes in the Asian southwest
monsoon during the Holocene and their links to the North Atlantic Ocean. Nature 421,
354-357.
Guttman, L., 1954. Some necessary conditions for common factor analysis. Psychometrika
19, 149-161.
Guy, A., Schulmann, K., Munschy, M., Miehe, J.-M., Edel, J.-B., Lexa, O., Fairhead, D.,
2014. Geophysical constraints for terrane boundaries in southern Mongolia. Journal of
Geophysical Research Solid Earth 119, 7966-7991.
Hammer, U.T., 1986. Saline lake ecosystems of the world. Monographiae Biologicae 59.
Kluwer Acad. Publ., Dordrecht.
139
Hartmann, K., Wünnemann, B., 2009. Hydrological changes and Holocene climate variations
in NW China, inferred from lake sediments of Juyanze palaeolake by factor analyses.
Quaternary International 194, 28-44.
Hartmann, K., Wünnemann, B., Hölz, S., Hrätschell, A., Zhang, H.C., 2011. Neotectonic
constraints on Gaxun Nur inland basin in north-central China, derived from remote
sensing, geomorphology and geophysical analyses. In: Gloaguen, R., Ratschbacher, L.,
(Eds.). Growth and collapse of the Tibetan Plateau. Geological Society London Special
Publications 353, 221-233.
Haug, G.H., Hughen, K.A., Sigman, D.M., Peterson, L.C., Röhl, U., 2001. Southward
migration of the Intertropical Convergence Zone through the Holocene. Science 293,
1304-1308.
Hempelmann, N.H., 2010. Aeolian geomorphodynamics in endorheic basins of Mongolian
Gobi Desert. Dissertation at Johannes Gutenberg-Universität Mainz, pp.31-57.
Herzschuh, U., 2006. Palaeo-moisture evolution in monsoonal Central Asia during the last
50,000 years. Quaternary Science Reviews 25, 163-178.
Heusser, L.E., 1989. Northeast Asian climatic change over the last 140,000 years inferred
from pollen in marine cores taken off the Pacific coast of Japan. In: Leinen, M.,
Sarnthein, M., (Eds.). Paleoclimatology and Paleometeorology: Modern and Past
Patterns of Global Atmospheric Transport. Dordrecht/Bosten/London, Kluwer
Academic Publishers, pp. 665-692.
Hilbig, W., 1995. Vegetation of Mongolia. SPB Academic Publishing, Amsterdam.
Hiller, D., 1972. Untersuchungen zur Biologie und zur Ökologie limnischer Ostracoden aus
der Umgebung von Hamburg. Archiv für Hydrobiologie, Supplement 40, 400-497.
Hillier, S., 1993. Origin, diagenesis, and mineralogy of chlorite minerals in Devonian
lacustrine mudrocks, Orcadian Basin, Scotland. Clays and Clay Minerals 41, 240-259.
Hölz, S., Polag, D., Becken, M., Fiedler-Volmer, R., Zhang, H.C., Hartmann, K., Burkhardt,
H., 2007. Electromagnetic and geoelectric investigation of the Gurinai Structure, Inner
Mongolia, NW China. Tectonophysics 445, 26-48.
Honda, M., Shimizu, H., 1998. Geochemical, mineralogical and sedimentological studies on
the Taklimakan Desert sands. Sedimentology 45, 1125-1143.
Honda, M., Yabuki, S., Shimizu, H., 2004. Geochemical and isotopic studies of aeolian
sediments in China. Sedimentology 51, 211-230.
Hong, B., Gasse, F., Uchida, M., Hong, Y.T., Leng, X.T., Shibata, Y., An, N., Zhu, Y.X.,
Wang, Y., 2014. Increasing summer rainfall in arid eastern-Central Asia over the past
8500 years. Scientific Report, doi:10.1038/srep05279.
Horiuchi, K., Minoura, K., Hoshino, K., Oda, T., Nakamura, T., Kawai, T., 2000.
Palaeoenvironmental history of Lake Baikal during the last 23,000 years.
Palaeogeography, Palaeoclimatology, Palaeoecology 157, 95-108.
140
Hövermann, J., 1988. The Sahara, Kalahari and Namib-Deserts: a geomorphological
comparison. In: Dardis, G.F., Moon, B.P., (Eds.). Geomorphological Studies in
Southern Africa. Balkema, Rotterdam, pp. 71-83.
Hovsgol Drilling Project Members, 2009. Sedimentary record from Lake Hovsgol, NW
Mongolia: Results from the HDP-04 and HDP-06 drill cores. Quaternary International
205, 21-37.
Hu, Z.X., Niu, Y.L., Liu, Y., Zhang, G.R., Sun, W.L., Ma, Y.X., 2014. Petrogenesis of
Ophiolite-type chromite deposits in China and some new perspectives. Geological
Journal of China Universities 20, 9-27.
Huang, W., Chen, J.H., Zhang, X.J., Feng, S., Chen, F.H., 2015. Definition of the core zone of
the “Westerlies-dominated climatic regime” and its controlling factors during the
instrumental period. Science China Earth Sciences 45, 379-388.
Hunt, J.E., Croudace, I.W., MacLachland, S.E., 2015. Use of calibrated ITRAX XRF data in
determining turbidite geochemistry and provenance in Agadir Basin, Northwest African
passive margin. In: Croudace, I.W., Guy Rothwell, R., (eds) Micro-XRF Studies of
Sediment Cores. Developments in Paleoenvironmental Research 17, pp 127-146.
Hülle, D., 2011. Lumineszenzdatierung von Sedimenten zur Rekonstruktion der jungquartären
Landschaftsentwicklung in der Mongolei. Dissertation zu Universität zu Köln.
IJmker, J.M., Stauch, G., Diekmann, B., Wünnemann, B., Lehmkuhl, F., 2012a. Dry periods
on the NE Tibetan Plateau during the late Quaternary. Palaeogeography,
Palaeoclimatology, Palaeoecology 346-347, 108-119.
IJmker, J.M., Stauch, G., Hartmann, K., Diekmann, B., Dietze, E., Opitz, S., Wünnemann, B.,
Lehmkuhl, F., 2012b. Environmental conditions in the Donggi Cona lake catchment,
NE Tibetan Plateau, based on factor analysis of geochemical data. Journal of Asian
Earth Sciences 44, 176-188.
Ilyashuk, B.P., Ilyashuk, E.A., 2007. Chironomid record of Late Quaternary climatic and
environmental changes from two sites in Central Asia (Tuva Republic, Russia) – local,
regional or global causes? Quaternary Science Reviews 26, 705-731.
ISO 14688-1, 2013. Geotechnical investigation and testing – Identification and classification
of soil – Part 1: Identification and description, ISO 14688-1: 2002 / Amd 1: 2013.
International Organization for Standardization, Geneva.
Ivanova, E.V., 2009. The Global Thermohaline Paleocirculation. Heidelberg, London, New
York, Springer Dordrecht.
Jahn, B.-M., Gallet, S., Han, J.M., 2001. Geochemical of the Xining, Xifeng and Jixian
sections, Loess Plateau of China: aeolian dust provenance and paleosol evolution during
the last 140 ka. Chemical Geology 178, 71-94.
Jankovská, V., Komárek, J., 2000. Indicative value of Pediastrum and other coccal green
algae in palaeoecology. Folia Geobotanica 35, 59-82.
141
Jiang, D.B., Lang, X.M., Tian, Z.P., Wang, T., 2012. Considerable model-data mismatch in
temperature over china during the Mid-Holocene: results of PMIP simulations. Journal
of Climate 25, 4135-4153.
Jiang, W.Y., Guo, Z.T., Sun, X.J., Wu, H.B., Chu, G.Q., Yuan, B.Y., Hatté, C., Guiot, J.,
2006. Reconstruction of climate and vegetation changes of Lake Bayanchagan (Inner
Mongolia): Holocene variability of the East Asian Monsoon. Quaternary Research 65,
411-420.
Jin, Z.D., An, Z.S., Yu, J.M., Li, F.C., Zhang, F., 2015. Lake Qinghai sediment geochemistry
linked to hydroclimate variability since the last glacial. Quaternary Science Reviews
122, 67-73.
Johnson, C.L., 2004. Polyphase evolution of the East Gobi basin: sedimentary and structural
records of Mesozoic-Cenozoic intraplate deformation in Mongolia. Basin Research 16,
79-99.
Johnsen, S.J., Dahl-Jensen, D., Gundestrup, N., Steffensen, J.P., Clausen, H.B., Miller, H.,
Masson-Delmotte, V., Sveinbjörnsdottir, A.E., White, J., 2001. Oxygen isotope and
palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3,
GRIP, GISP2, Renland and NorthGRIP. Journal of Quaternary Sciences 16, 299-307.
Johnsson, M.J.,1993. The system controlling the composition of clastic sediments. Geological
Society of America Special Paper 284, 1-20.
Juschus, O., Pavlov, M., Schwamborn, G., Preusser, F., Fedorov, G., Melles, M., 2011. Late
Quaternary lake-level changes of Lake El’gygytgyn, NE Siberia. Quaternary Research
76, 441-451.
Kaiser, H.F., 1958. The varimax criterion for analytic rotation in factor analysis.
Psychometrika 23, 187–200.
Kaiser, H.F., 1960. The application of electronic computers to factor analysis. Educational
and Psychological Measurement 20, 141-151.
Karabanov, E.B., Prokopenko, A.A., Williams, D.F., Khursevich, G.K., 2000. A new record
of Holocene climate change from the bottom sediments of Lake Baikal.
Palaeogeography, Palaeoclimatology, Palaeoecology 156, 211-224.
Karabanov, E.B., Williams, D., Kuzmin, M., Sideleva, V., Khursevich, G., Prokopenko, A.,
Solotchina, E., Tkachenko, L., Fedenya, S., Kerber, E., Gvozdkov, A., Khlustov, O.,
Bezrukova, E., Letunova, P., Krapivina, S., 2004. Ecological collapse of Lake Baikal
and Lake Hovsgol ecosystems during the Last Glacial and consequences for aquatic
species diversity. Palaeogeography, Palaeoclimatology, Palaeoecology 209, 227-243.
Kazancı, N., Gulbabazadeh, T., Leroy, S.A.G., Ataselim, Z., Gürbüz, A., 2016. Aeolian
control on the deposition of high altitude lacustrine basins in the Middle East: The case
of Lake Neor, NW Iran. Quaternary International, doi:
dx.doi.org/10.1016/j.quaint.2015.11.040.
Kerr, R.A., 2003. Tropical Pacific a key to deglaciation. Science 299, 183-184.
142
Klinge, M., Böhner, J., Lehmkuhl, F., 2003. Climate pattern, snow- and timberlines in the
Altai Mountains, central Asia. Erdkunde 57, 296-308.
Klinge, M., Lehmkuhl, F., 2013. Geomorphologic map of Tsetseg Nuur Basin, Mongolian
Altai-lake development, fluvial sedimentation and aeolian transport in a semi-arid
environment. Journal of Maps 9, 361-366.
Komatsu, G., Brantingham, P.J., Olsen, J.W., Baker, V.R., 2001. Paleoshoreline
geomorphology of Böön Tsagaan Nuur, Tsagann Nuur and Orog Nuur: the Valley of
Lakes, Mongolia. Geomrphology 39, 83-98.
Komatsu, T., Tsukamoto, S., 2015. Late Glacial lake-level changes in the Lake Karakul basin
(a closed glacierized-basin), eastern Pamirs, Tajikistan. Quaternary Research 83, 137-
149.
Konert, M., Vandenberghe, J., 1997. Comparison of laser grain size analysis with pipette and
sieve analysis: a solution for the underestimation of the clay fraction. Sedimentology 44,
523-535.
Kostrova, S.S., Meyer, H., Chapligin, B., Tarasov, P.E., Bezrikova, E.V., 2014. The last
glacial maximum and late glacial environmental and climate dynamics in the Baikal
region inferred from an oxygen isotope record of lacustrine diatom silica. Quaternary
International 348, 25-36.
Kovács, J., 2008. Grain-size analysis of the Neogene red clay formation in the Pannonian
Basin. International Journal of Earth Sciences 97, 171-178.
Kramer, A., Herzschuh, U., Mischke, S., Zhang, C.J., 2010. Late Quaternary environment
history of the south-eastern Tibetan plateau inferred from the lake Naleng non-pollen
palynomorph record. Vegetation History and Archaeobotany 19, 453-468.
Kylander, M.E., Ampel, L., Wohlfarth, B., Veres, D., 2011. High-resolution X-ray
fluorescence core scanning analysis of Les Echets (France) sedimentary sequence: new
insights from chemical proxies. Journal of Quaternary Science 26, 109-117.
Lai, Z.P., Mischke, S., Madson, D., 2014. Paleoenvironmental implications of new OSL dates
on the formation of the “Shell Bar” in the Qaidam Basin, northeastern Qinghai-Tibetan
Plateau. Journal of Paleolimnology 51, 197-210.
Lamb, H., Bates, C., Coombes, P., Marshall, M., Umer, M., Davies, S., Dejen, E., 2007. Late
Pleistocene desiccation of Lake Tana, source of the Blue Nile. Quaternary Science
Reviews 26, 287–299.
Last, W.M., 1990. Lacustrine dolomite-an overview of modern, Holocene, and Pleistocene
occurrences. Earth-Science Reviews 27, 211-263.
Lauterbach, S., Brauer, A., Andersen, N., Danielopol, D., Dulski, P., Hüls, M., Milecka, K.,
Namiotko, T., Obremska, M., Grafenstein, U., Participants, D., 2011. Environmental
responses to Lateglacial climatic fluctuations recorded in the sediments of pre-alpine
Lake Mondsee (northeastern Alps). Journal of Quaternary Science 26, 253–267.
143
Lee, M.K., Lee, Y.I., Lim, H.S., Lee, J.I., Choi, J.H., Yoon, H.I., 2011. Comparison of
radiocarbon and OSL dating methods for a Late Quaternary sediment core from Lake
Ulaan, Mongolia. Journal of Paleolimnology 45, 127-135.
Lee, M.K., Lee, Y.I., Lim, H.S., Lee, J.I., Yoon, H.I., 2013. Late Pleistocene-Holocene
records from Lake Ulaan, southern Mongolia: implications for East Asian
palaeomonsoonal climate changes. Journal of Quaternary Sciences 28, 370-378.
Lehmkuhl, F., 1997. Flächenhafte Erfassung der Landschaftsdegradation im Becken von
Zoige (Osttibet) mit Hilfe von Landsat-TM-Daten. Göttinger Geographische
Abhandlungen 100, 179-194.
Lehmkuhl, F., Böhner, J., Stauch, G., 2003. Geomorphologische Formungs- und
Prozessregionen in Zentralasien. Petermanns Geographische Mitteilungen 147, 6-13.
Lehmkuhl, F., Haselein, F., 2000. Quaternary paleoenvironmental change on the Tibetan
Plateau and adjacent areas (western China and western Mongolia). Quaternary
International 65/66, 121-145.
Lehmkuhl, F., Klinge, M., Rother, H., Hülle, D., 2015. Distribution and timing of Holocene
and late Pleistocene glacier fluctuations in western Mongolia. Annals of Glaciology 71,
doi: dx.doi.org/10.3189/2016AoG71A030.
Lehmkuhl, F., Klinge, M., Stauch, G., 2011. The extent and timing of Late Pleistocene
glaciations in the Altai and neighboring mountain systems. In: Ehlers, J., Gibbard, P.L.,
Hughes, P.D., (Eds.). Developments in Quaternary Sciences 15, Amsterdam, The
Netherlands, 967-979.
Lehmkuhl, F., Lang, A., 2001. Geomorphological investigations and luminescence dating in
the southern part of the Khangay and the Valley of the Gobi Lakes (Central Mongolia).
Journal of Quaternary Sciences 16, 69-87.
Lehmkuhl, F., Schulte, P., Zhao, H., Hülle, D., Protze, J., Stauch, G., 2014. Timing and
spatial distribution of loess and loess-like sediments in the mountain areas of the
northeastern Tibetan Plateau. Catena 117, 23-33.
Leinen, M., 1989. The late Quaternary record of atmospheric transport to the northwest
Pacific from Asia. In: Leinen, M., Sarnthein, M., (Eds.). Paleoclimatology and
Paleometeorology: Modern and Past Patterns of Global Atmospheric Transport.
Dordrecht/Bosten/London, Kluwer Academic Publishers, pp. 693-732.
Li, X.Q., Zhao, K.L., Dodson, J., Zhou, X.Y., 2011. Moisture dynamics in central Asia for the
last 15 k: new evidence from Yili Valley, Xinjiang, NW China. Quaternary Science
Reviews 30, 3457-3466.
Liang, L.J., Jiang, H.C., 2015. Geochemical composition of the last deglacial lacustrine
sediments in East Tibet and implications for provenance, weathering, and earthquake
events. Quaternary International, doi:10.1016/j.quaint.2015.07.037.
Lisiecki, L.E., Raymo, M.E., 2005. A Pliocene-Pleistocene stack of 57 globally distributed
benthic δ18O records. Paleoceanography 20, PA1003, doi: 10.1029/2004PA001071.
144
Lister, G.S., Kelts, K., Chen, K.Z., Yu, J.Q., Niessen, F., 1991. Lake Qinghai, China: closed-
basin lake levels and the oxygen isotope record for ostracoda since the latest
Pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology 84, 141-162.
Liu, C.Q., Masuda, A., Okada, A., Yabuki, S., Zhang, J., Fan, Z.L., 1993. A geochemical
study of loess and desert sand in northern China: Implications for continental crust
weathering and composition. Chemical Geology 106, 359-374.
Liu, X.J., Lai, Z.P., Fan, Q.S., Long, H., Sun, Y.J., 2010. Timing for high lake levels of
Qinghai Lake in the Qinghai-Tibetan Plateau since the Last Interglaciation based on
quartz OSL dating. Quaternary Geochronology 5, 218-222.
Liu, Z.Y., Otto-Bliesner, B.L., He, F., Brady, E.C., Tomas, R., Clark, P.U., Carlson, A.E.,
Lynch-Stieglitz, J., Curry, W., Brook, E., Erickson, D., Jacob, R., Kutzbach, J., Cheng,
J., 2009. Transient simulation of Last Deglaciation with a now mechanism for Bølling-
Allerød warming. Science 325, 310-314.
Loibl, D., 2015. Late Holocene glacier change in the eastern Nyainqêntanglha Range, SE
Tibet. Dissertation to RWTH Aachen University, Aachen, p. 5.
Long, H., Shen, J., 2015. Underestimated 14C-based chronology of late Pleistocene high lake-
level events over the Tibetan Plateau and adjacent areas: evidence from the Qaidam
Basin and Tengger Desert. Science China Earth Sciences 58, 183-194.
Lu, H.Y., Sun, D.H., 2000. Pathways of dust input to the Chinese Loess Plateau during the
last glacial and interglacial periods. Catena 40, 251-261.
Lu, H.Y., Vandenberghe, J., An, Z.S., 2001. Aeolian origin and palaeoclimatic implications of
the 'red clay' (north China) as evidenced by grain-size distribution. Journal of
Quaternary Science 16, 89-97.
Lu, H.Y., Yi, S.W., Xu, Z.W., Zhou, Y.L., Zeng, L., Zhu, F.Y., Feng, H., Dong, L.N., Zhuo,
H.X., Yu, K.F., Mason, J., Wang, X.Y., Chen, Y.Y., Lu, Q., Wu, B., Dong, Z.B., Qu,
J.J, Wang, X.M., Guo, Z.T., 2013. Chinese deserts and sand fields in Last Glacial
Maximum and Holocene Optimum. Chinese Science Bulletin 58, 2775-2783.
Lu, H.Y., Zhao, C.F., Mason, J., Yi, S.W., Zhao, H., Zhou, Y.L., Ji, J.F., Swinehart, J., Wang,
C.M., 2010. Holocene climate changes revealed by aeolian deposits from the Qinghai
Lake area (northeastern Qinghai-Tibetan Plateau) and possible forcing mechanisms. The
Holocene 21, 297-304.
Lupker, M., France-Lanord, C., Lavé, J., Bouchez, J., Galy, V., Métivier, F., Gaillardet, J.
Lartiges, B., Mugnier, J., 2011. A Rouse-based method to integrate the chemical
composition of river sediments: Application to the Ganga basin. Journal of Geophysical
Research 116, doi: 10.1029/2010JF001947.
Ma, Y.Z., Liu, K.-B., Feng, Z.D., Meng, H.W., Sang, Y.L., Wang, W., Zhang, H.C., 2013.
Vegetation changes and associated climate variations during the past ~38,000 years
reconstructed from the Shaamar eolian-paleosol section, northern Mongolia. Quaternary
International 311, 25-35.
145
Ma, Y.Z., Liu, K.-B., Feng, Z.D., Sang, Y.L., Wang, W., Sun, A.Z., 2008. A survey of
modern pollen and vegetation along a south-north transect in Mongolia. Journal of
Biogeography 35, 1512-1532.
Mackay, A.W., Bezrukova, E.V., Leng, M.J., Meaney, M., Nunes, A., Piotrowska, N., Self,
A., Shchetnikov, A., Shilland, E., Tarasov, P., Wang, L, White, D., 2012. Aquatic
ecosystem responses to Holocene climate change and biome development in boreal,
central Asia. Quaternary Science Review 41, 119-131.
Madsen, D.B., Ma, H.Z., Rhode, D., Jeffrey Brantingham, P., Forman, S.L., 2008. Age
constraints on the late Quaternary evolution of Qinghai Lake, Tibetan Plateau.
Quaternary Research 69, 316-325.
Maher, B.A., Mutch, T.J., Cunningham, D., 2009. Magnetic and geochemical characteristics
of Gobi Desert surface sediments: Implications for provenance of the Chinese Loess
Plateau. Geology 37, 279-282.
Martinez-Ruiz, F., Kastner, M., Gallego-Torres, D., Rodrigo-Gámiz, M., Nieto-Moreno, V.,
Ortega-Huertas, M., 2015. Paleoclimate and paleoceanography over the past 20,000 yr
in the Mediterranean Sea Basins as indicated by sediment elemental proxies.
Quaternary Science Reviews 107, 25-46.
Mason, J.A., Greene, R.S.B., Joeckel, R.M., 2011. Laser diffraction analysis of the
disintegration of aeolian sedimentary aggregates in water. Catena 87, 107-118.
McLennan, S.M., 1993. Weathering and global denudation. The Journal of Geology 101, 295-
303.
McLennan, S.M., 2001. Relationships between the trace element composition of sedimentary
rocks and upper continental crust. Geochemistry, Geophysics, Geosystems 2, doi:
10.1029/2000GC000109.
Meisch, F., 2000. Freshwater ostracoda of western and central Europe. Spektrum, Gustav
Fischer, p. 522.
Melles, M., Brigham-Grette, J., Minyuk, P.S., Nowaczyk, N.R., Wennrich, V., DeConto,
R.M., Anderson, P.M., Andreev, A.A., Coletti, A., Cook, T.L., Haltia-Hovi, E.,
Kukkonen, M., Lozhkin, A.V., Rosén, P., Tarasov, P., Vogel, H., Wagner, B., 2012. 2.8
million years of Arctic climate change from Lake El’gygytgyn, NE Russia. Science 337,
315-320.
Meyers, P.A., Lallier-Vergès, E., 1999. Lacustrine sedimentary organic matter records of Late
Quaternary paleoclimates. Journal of Paleolimnology 21, 345-372.
Meyers, P.A., Teranes, J.L., 2001. Sediment organic matter. In: Last, W.M., Smol, J.P.,
(Eds.). Tracking Environmental Changes Using Lake Sediments. Vol. 2: Physical and
Geochemical Methods, pp. 239-270.
Miehe, G., Schlütz, F., Miehe, S., Opgenoorth, L., Cermak, J., Samiya, R., Jäger, E.J.,
Wesche, K., 2007. Mountain forest islands and Holocene environmental changes in
Central Asia: A case study from the southern Gobi Altay, Mongolia. Palaeogeography,
Palaeoclimatology, Palaeoecology 250, 150-166.
146
Millot, G., 1970. Geology of Clays, Weathering, Sedimentology, Geochemistry. Springer-
Verlag Wien Gmbh, Vienna, pp. 357-381.
Mischke, S., Demske, D., Shudack, M.E., 2003. Hydrologic and climatic implications of a
multidisciplinary study of the mid to late Holocene Lake Eastern Juyanze. Chinese
Science Bulletin 48, 1411-1417.
Mischke, S., Herzschuh, U., Zhang, C.J., Bloemendal, J., Riedel, F., 2005. A Late Quaternary
lake record from the Qilian Mountains (NW China): lake level and salinity changes
inferred from sediment properties and ostracod assemblages. Global and Planetary
Changes 46, 337-359.
Mischke, S., Weynell, M., Zhang, C.J., Wiechert, W., 2013. Spatial variability of 14C
reservoir effects in Tibetan Plateau lakes. Quaternary International 313-314, 147-155.
Mischke, S., Zhang, C.J., 2011. Ostracod distribution in Ulungur Lake (Xinjiang, China) and
a reassessed Holocene record. Ecological Research 26: 133-145.
Mölg, T., Maussion, F., Scherer, D., 2013. Mid-latitude westerlies as a driver of glacier
variability in monsoonal High Asia. Nature Climate Change 4, 68-73.
Moore, P.D., Webb, J.A., Collinson, M.E., 1991. Pollen analysis, 2nd. Ed. Oxford: Blacwell
Scientific Publication.
Moros, M., Emeis, K., Risebrobakken, B., 2004. Sea surface temperature and ice rafting in the
Holocene North Atlantic: Climate influences on northern Europe and Greenland.
Quaternary Science Reviews 23: 2113-2160.
Mukherji, A.K., 1970. Analytical chemistry of zirconium and hafnium. Pergamon Press,
Oxford, pp. 1-11.
Murad, W., 2011. Late Quaternary vegetation history and climate change in the Gobi Desert,
south Mongolia. Dissertation at Georg-August-Universität Göttingen, pp.67-82.
Murakami, T., Katsuta, N., Yamamoto, K., Takamatsu, N., Takano, M., Oda, T., Matsumoto,
G.I., Horiuchi, K., Kawai, T., 2010. A 27-k record of environmental change in central
Asia inferred from the sediment record of Lake Hovsgol, northwest Mongolia. Journal
of Paleolimnology 43, 369-383.
Murakami, T., Takamatsu, T., Katsuta, N., Takano, M., Yamamoto, K., Takahashi, Y.,
Nakamura, T., Kawai, T., 2012. Centennial- to millennial-scale climate shifts in
continental interior Asia repeated between warm-dry and cool-wet conditions during the
last three interglacial states: evidence from uranium and biogenic silica in the sediment
of Lake Baikal, southeast Siberia. Quaternary Science Reviews 52, 49-59.
Murray, A.S., Wintle, A.G., 2003. The single aliquot regenerative dose protocol: potential for
improvements in reliability. Radiation Measurements 37, 377-381.
Murray, R.W., Buchholtz Ten Brink, M.R., Gerlach, D.C., Price Russ III, G., Jones, D.L.,
1992. Rare earth, major, and trace element composition of Monterey and DSDP chert
and associated host sediment: Assessing the influence of chemical fractionation during
diagenesis. Geochemica et Cosmochimica Acta 56, 2657-2671.
147
Nakagawa, T., Kitagawa, H., Yasuda, Y., Tarasov, P.E., Nishida, K., Gotanda, K., Sawai, Y.,
Yangtze River Civilization Program Members, 2003. Asynchronous climate changes in
the north Atlantic and Japan during the Last Termination. Science 299, 688-691.
Nakai, S., Halliday, A.N., Rea, D.K., 1993. Provenance of dust in the Pacific Ocean. Earth
and Planetary Science Letters 119, 143-157.
Nagashima, K., Tada, R., Tani, A., Toyoda, S., Sun, Y.B., Isozaki, Y., 2007. Contribution of
aeolian dust in Japan Sea sediments estimated from ESR signal intensity and
crystallinity of quartz. Geochemistry, Geophysics, Geosystems 8, doi:
10.1029/2006GC001364.
Naumann, S., 1999. Spät- und postglaziale Landschaftsentwicklung im Bajan Nuur
Seebecken (Nordwestmongolei). Die Erde 130, 117-130.
Nesbitt, H.W., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred
from major element chemistry of lutites. Nature 299, 715-717.
Nesbitt, H.W., Young, G.M., 1996. Petrogenesis of sediments in the absence of chemical
weathering: effects of abrasion and sorting on bulk composition and mineralogy.
Sedimentology 43, 341-358.
Nickel, E.H., 1954. The distribution of major and minor elements among some co-existing
ferromagnesian silicates. American Mineralogist 6, 486-493.
Nilson, E., Lehmkuhl, F., 2001. Interpreting temporal patterns in the late Quaternary dust flux
from Asia to the North Pacific. Quaternary International 76/77, 67-76.
NIOZ, Avaatech, 2007. XRF core scanner user manual version 2.0. Royal Netherlands
Institute of Sea Research and Avaatech XRF Core Scanner Technology.
Norman, M.D., De Deckker, P., 1990. Trace metals in lacustrine and marine sediments: A
case study from the Gulf of Carpentaria, northern Australia. Chemical Geology 82, 299-
318.
Nottebaum, V., Lehmkuhl, F., Stauch, G., Hartmann, K., Wünnemann, B., Schimpf, S., Lu,
H.Y., 2014. Regional grain size variations in aeolian sediments along the transition
between Tibetan highlands and north-western Chinese deserts – the influence of
geomorphology settings on aeolian transport pathways. Earth Surface Processes
Landforms, doi: 10.1002/sep.3590.
Nottebaum, V., Lehmkuhl, F., Stauch, G., Lu, H.Y., Yi, S.W., 2015a. Late Quaternary aeolian
sand deposition sustained by fluvial reworking and sediment supply in the Hexi
Corridor — An example from northern Chinese drylands. Geomorphology 250, 113-
127.
Nottebaum, V., Stauch, G., Hartmann, K., Zhang, J.R., Lehmkuhl, F., 2015b. Unmixed loess
grain size populations along the northern Qilian Shan (China): Relations between
geomorphologic, sedimentologic and climatic controls. Quaternary International 372,
151-166.
148
Ohlendorf, C., Wennrich, V., Enters, D., 2015. Experiences with XRF-Scanning of Long
Sediment Records. In: Croudace, I.W., Guy, Rothwell, R., (eds) Micro-XRF Studies of
Sediment Cores. Developments in Paleoenvironmental Research 17, pp 351-372.
Orkhonselenge, A., Krivonogov, S.K., Mino, K., Kashiwaya, K., Safonova, I.Y., Yamamoto,
M., Kashima, K., Nakamura, T., Kim, J.Y., 2013. Holocene sedimentary records from
Lake Borsog, eastern shore of Lake Khuvsgul, Mongolia, and their paleoenvironmental
implications. Quaternary International 290-291, 95-109.
Owen, L.A., Cunningham, W.D., Richards, B.W.M., Rhodes, E., Windley, B.F., Dorjnamajaa,
D., Badamgarav, J., 1999. Timing of formation of forebergs in the northeastern Gobi
Altai, Mongolia: implications for estimating mountain uplift rates and earthquake
recurrence intervals. Journal of the Geological Society, London 156, 457-464.
Owen, L.A., Richards, B., Rhodes, E.J., Cunningham, W.D., Windley, B.F., Badamgarav, J.,
Dorjnamjaa, D., 1998. Relic permafrost structures in the Gobi of Mongolia: age and
significance. Journal of Quaternary Sciences 13, 539-547.
Owen, L.A., Windley, B.F., Cunningham, W.D., Badamgarav, J., Dorjnamjaa, D., 1997.
Quaternary alluvial fans in the Gobi of southern Mongolia: evidence for neotectonics
and climate change. Journal of Quaternary Sciences 12, 239-252.
Owen, M.R., 1987. Hafnium content of detrital zircons, a new tool for provenance study.
Journal of Sedimentary Petrology 57, 824-830.
Özer, M., Orhan, M., Isik, N. S., 2010. Effect of particle optical properties on size distribution
of soils obtained by laser diffraction. Environmental & Engineering Geoscience 16,
163-173.
Pachur, H.-J., Wünnemann, B., 1995. Lake evolution in the Tengger Desert, northwestern
China, during the last 40,000 years. Quaternary Research 44, 171-180.
Parnell, A.C., Haslett, J., Allen, J.R.M., Buck, C.E., Huntley, B., 2008. A flexible approach to
assessing synchronicity of past events using Bayesian reconstructions of sedimentation
history. Quaternary Science Reviews 27, 1872–1885.
Peck, J.A., Khosbayar, P., Fowell, S.J., Pearce, R.B., Ariunbileg, S., Hansen, B.C.S.,
Soninkhishig, N., 2002. Mid to Late Holocene climate change in north central Mongolia
as recorded in the sediments of Lake Telmen. Palaeogeography, Palaeoclimatology,
Palaeoecology 183, 135-153.
Pederson, N., Hessl, A.E., Baatarbileg, N., Anchukaitis, K.J., Di Cosmo, N., 2014. Pluvials,
droughts, the Mongol Empire, and modern Mongolia. Proceedings of the National
Academy of Sciences, doi:10.1073/pnas.1318677111.
Peltier, W.R., Fairbanks, R.G., 2006. Global glacial ice volume and Last Glacial Maximum
duration from an extended Barnados sea level record. Quaternary Science Reviews 25,
3322-3337.
Petschick, R., Kuhn, G., Gingele, F.X., 1996. Clay mineral distribution in surface sediments
of the South Atlantic: Sources, transport, and relation to oceanography. Marrine
Geology 130, 203-229.
149
Pettijohn, F.J., Potter, P.E., Siever, R., 1973. Sand and Sandstone. Springer-Verlag, New
York, pp. 24-63.
Porter, S.C., An, Z.S., 1995. Correlation between climate events in the north Atlantic and
China during the last glaciation. Nature 375, 305-308.
Prescott, J.R., Hutton, J.R., 1994. Cosmic ray contribution to dose rate for luminescence and
ESR dating: Large depth and long-term variations. Radiation Measurements 23, 479-
500.
Prins, M.A., Vriend, M., Nugteren, G., Vandenberghe, J., Lu, H.Y., Zheng, H.B., Weltje, G.J.,
2007. Late Quaternary aeolian dust input variability on the Chinese Loess Plateau:
inferences from unmixing of loess grain-size records. Quaternary Science Reviews 26,
230-242.
Prokopenko, A.A., Karabanov, E.B., Williams, D.F., Kuzmin, M.I., Khursevich, G.K.,
Gvozdkov, A.A., 2001. The detailed record of climatic events during the past 75,000 s
BP from the Lake Baikal drill core BDP-93-2. Quaternary International 80/81, 59-68.
Prokopenko, A.A., Karabanov, E.B., Williams, D.F., Khursevich, G.K., 2002. The stability
and the abrupt ending of the last Interglaciation in southeastern Siberia. Quaternary
Research 58, 56-59.
Prokopenko, A.A., Khursevich, G.K., Bezrukova, E.V., Kuzmin, M.I., Boes, X., Williams,
D.F., Fedenya, S.A., Kulagina, N.V., Letunova, P.P., Abzaeva, A.A., 2007.
Paleoenvironmental proxy records from Lake Hovsgol, Mongolia, and a synthesis of
Holocene climate change in the Lake Baikal watershed. Quaternary Research 68, 2-17.
Pye, K., Zhou, L.P., 1989. Late Pleistocene and Holocene Eolian Dust Deposition in North
China and the Northwest Pacific Ocean. Palaeogeography, Palaeoclimatology,
Palaeoecology 73, 11-23.
Rahmstorf, S., 2002. Ocean circulation and climate during the past 120,000 years. Nature
419, 207-214.
Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C.,
Grootes, P.M., Guilderson, T. P., Haflidason, H., Hajdas, I., HattŽ, C., Heaton, T. J.,
Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S.
W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A.,
Turney, C. S. M., van der Plicht, J., 2013. IntCal13 and Marine13 Radiocarbon Age
Calibration Curves 0-50,000 Years cal BP. Radiocarbon 55, 1869-1887.
Rhodes, T.E., Gasse, F., Lin, R.F., Fontes, J.-C., Wei, K.Q., Bertrand, P., Gibert, E., Mélières,
F., Tucholka, P., Wang, Z.X., Cheng, Z.Y., 1996. A Late-Holocene lacustrine record
from Lake Manas, Zunggar (northern Xinjiang, western China). Palaeogeography,
Palaeoclimatology, Palaeoecology 120, 105-121.
Richter, R.O., van der Gaast, S., Koster, R., Vaars, A., Gieles, R., de Stigter, H.C., de Haas,
H., van Weering, T.C.E., 2006. The Avaatech XRF Core Scanner: technical description
and applications to NE Atlantic sediments. In: Rothwell, R.G., (ed) New techniques in
sediment core analysis. Geological Society London Special Publications 267, 39-50.
150
Ritz, J.-F., Vassallo, R., Braucher, R., Brown, E.T., Carretier, S., Bourlès, D.L., 2006. Using
in situ-produced 10Be to quantify active tectonics in the Gurvan Bogd mountain range
(Gobi-Altay, Mongolia). Geological Society of America Special Paper 415, 87-109.
Rodwell, M.J., Rowell, D.P., Folland, C.K., 1999. Oceanic forcing of the wintertime North
Atlantic Oscillation and European climate. Nature 398, 320-323.
Roser, B.P., Korsch, R.J., 1988. Provenance signatures of sandstone-mudstone suites
determined using discriminant function analysis of major-element data. Chemical
Geology 67, 119-139.
Rother, H., Lehmkuhl, F., Fink, D., Nottebaum, V., 2014. Surface exposure dating reveals
MIS-3 glacial maximum in the Khangai Mountains of Mongolia. Quaternary Research
82, 297-308.
Roy, P.D., Caballero, M., Lozano, S., Morton, O., Lozano, R., Jonathan, M.P., Sánchez, J.L.,
Macías, M.C., 2012. Provenance of sediments deposited at plaeolake San Felipe,
western Sonora Desert: Implications to regimes of summer and winter precipitation
during last 50 cal kyr BP. Journal of Arid Environments 81, 47-58.
Rudaya, N., Tarasov, P., Dorofeyuk, N., Solovieva, N., Kalugin, I., Andreev, A., Daryin, A.,
Diekmann, B., Riedel, F., Tserendash, N., Wagner, M., 2009. Holocene environments
and climates in the Mongolian Altai reconstructed from the Hoton-Nur pollen and
diatom records: a step towards better understanding climate dynamics in Central Asia.
Quaternary Science Reviews 28, 540-554.
Rudersdorf, A., Hartmann, K., Yu, K.F., Stauch, G., Reicherter, K., 2015. Seismites as
indicators for Holocene seismicity in the northeastern Ejina Basin, Inner Mongolia,
China. In: Landgraf, S., Stein, S., Hintersbergen, E., (Eds.). Seismicity, Fault Rupture
and Earthquake Hazards in Slowly Deforming Regions. Geological Society London
Special Publications 432, doi: 10.1144/SP432.6.
Rudnick, R.L., Gao, S., 2003. Composition of the continental crust. In: Holland, H.D.,
Turekian, K.K., (Eds.). Treatise on Geochemistry, vol. 3. Elservier-Pergamon, Oxford-
London, pp. 53-54.
Sato, T., Tsujimura, M., Yamanaka, T., Iwasaki, H., Sugimoto, A., Sugita, M., Kimura, F.,
Davaa, G., Oyunbaatar, D., 2007. Water sources in semiarid northwest Asia as revealed
by field observations and isotope transport model. Journal of Geophysical Research,
doi: 10.1029/2006JD008321.
Scheffer, F., Schachtschabel, P., 2002. Lehrbuch der Bodenkunde. 15. Auflage. Spektrum
Akademischer Verlag, Derdelberg, Berlin.
Schettler, G., Romer, R.L., Qiang, M.R., Plessen, B., Dulski, P., 2009. Size-dependent
geochemical signatures of Holocene loess deposits from the Hexi Corridor (China).
Journal of Asian Earth Sciences 35, 103-136.
Schillereff, D.N., Chiverrell, R.C., Croudace, I.W., Boyle, J.F., 2015. An Inter-comparison of
µXRF Scanning Analytical Methods for Lake Sediments. In: Croudace, I.W., Guy
Rothwell, R. (eds) Micro-XRF Studies of Sediment Cores. Developments in
Paleoenvironmental Research 17, pp 583-600.
151
Schimpf, S., Nottebaum, V., Diekmann, B., Hartmann, K., Lehmkuhl, F., Wünnemann, B.,
Zhang, C.J., 2014. From source to sink in the sediment cascade of the Hei-River Basin:
Implications for late Quaternary landscape dynamics in the Gobi Desert, NW China.
Geophysical Research Abstracts 16, EGU2014-9905.
Schlütz, F., Lehmkuhl, F., 2007. Climatic change in the Russian Altai, southern Siberia based
on palynological and geomorphological results with implications for climatic
teleconnections and human history since the middle Holocene. Vegetation History and
Archaeobotany 16, 101-118.
Schulte, P., Lehmkuhl, F., Steininger, F., Loibl, D., Lockot, G., Protze, J., Fischer, P., Stauch,
G., 2016. Influence of HCl pretreatment and organo-mineral complexes on laser
diffraction measurement of loess-paleosol-sequences. Catena 137, 392-405.
Schwanghart, W., Frechen, M., Kuhn, N.J., Schütt, B., 2009. Holocene environmental
changes in the Uggi Nuur basin, Mongolia. Palaeogeography, Palaeoclimatology,
Palaeoecology 279, 160-171.
Schwanghart, W., Schütt, B., Walther, M., 2008. Holocene climate evolution of the Ugii Nuur
Basin, Mongolia. Advances in Atmospheric Sciences 25, 986-998.
Selvaraj, K., Chen, C.-T. A., Babu C.P., Lou, J.Y., Liu, C.-L., Hsu, K.J., 2012. Glacially
derived material in an Inner Mongolian desert lake during the Marine Isotope Stage 2.
Journal of Quaternary Science 27, 725-733.
Shanahan, T.M., McKay, N., Overpeck, J.T., Peck, J.A., Scholz, C., Heil, C.W., King, J.,
2013. Spatial and temporal variability in sedimentological and geochemical properties
of sediments from an anoxic crater lake in West Africa: implications for
paleoenvironmental reconstructions. Palaeogeography, Palaeoclimatology,
Palaeoecology 374, 96-109.
Shanahan, T.M., Overpeck, J.T., Hubeny, J.B., King, J., Hu, F.S., Hughen, K., Miller, G.,
Black, J., 2008. Scanning micro-X-ray fluorescence elemental mapping: A new tool for
the study of laminated sediment records. Geochemistry, Geophysics, Geosystems 9,
Q02016, doi: 10.1029/2007GC001800.
Shichi, K., Takahara, H., Krivonogov, S.K., Bezrukova, E.V., Kashiwaya, K., Takehara, A.,
Nakamura, T., 2009. Late Pleistocene and Holocene vegetation and climate records
from Lake Kotokel, central Baikal region. Quaternary International 205, 98-110.
Sirocko, F., Sarnthein, M., Erlenkeuser, H., 1993. Century-scale events in monsoonal climate
over the past 24,000 years. Nature 364, 322-324.
Smith, G.I., Haines, D.V., 1964. Character and distribution of nonclastic minerals in the
Searles Lake evaporate deposit, California. United States Government Publishing Office
1181, pp. 1-58.
Spearman, C., 1904. The proof and measurement of association between two things. Journal
of Psychology 15, 72-101.
Spectro Xepos, 2007. Analysis of trace elements in geological materials, soils and sludges.
SPECTRO XRF Report, 1-5.
152
Staubwasser, M., Weiss, H., 2006. Holocene climate and cultural evolution in late prehistoric-
early historic West Asia. Quaternary Research 66, 372-387.
Stebich, M., Mingram, J., Han, J.T., Liu, J.Q., 2009. Late Pleistocene spread of (cool-)
temperate forests in Northeast China and climate changes synchronous with the North
Atlantic region. Global and Planetary Change 65, 56-70.
Stein, R., Grobe, H., Wahsner, M., 1994. Organic carbon, carbonate, and clay mineral
distributions in eastern central Arctic Ocean surface sediments. Marine Geology 119,
269-285.
Stevens, T., Palk, C., Carter, A., Lu, H.Y., Clift, P.D., 2010. Assessing the provenance of
loess and desert sediments in northern China using U-Pb dating and morphology of
detrital zircons. Geological Society of America Bulletin 122, 1331-1344.
Stolz, C., Hülle, D., Hilgers, A., Grunert, J., Lehmkuhl, F., Dasch, D., 2012. Reconstructing
fluvial, lacustrine and aeolian process dynamics in Western Mongolia. Zeitschrift für
Geomorphologie 56, 267-230.
Stuiver, M.P., Reimer, J., Bard, E., Burr, G.S., Hughen, K.A., Kromer, B., McCormac, G.,
Plicht, J.v.d., Spurk, M., 1998. INTCAL98 radiocarbon age calibration. Radiocarbon
40, 1041-1083.
Sun, D.H., 2004. Monsoon and westerly circulation changes recorded in the late Cenozoic
aeolian sequences of Northern China. Global and Planetary Change 41, 63-80.
Sun, D.H., Lu, H.Y., David, R., Sun, Y.B., Wu, S.G., 2000. Bimode grain size distribution of
Chinese Loess and its paleoclimate implication. Acta Sedimentologica Sinica 18, 327-
335.
Sun, Y.B., Tada, R., Chen, J., Liu, Q.S., Toyoda, S., Tani, A., Ji, J.F., Isozaki, Y., 2008.
Tracing the provenance of fine-grained dust deposited on the central Chinese Loess
Plateau. Geophysical Research Letters, doi: 10.1029/2007GL031672.
Tamura, K., Asano, M., Jamsran, U., 2012. Soil diversity in Mongolia. In
: Yamamura, N., Fujita, N., Maekawa, A., (Eds.). The Mongolian Ecosystem Network,
Environmental Issues under Climate and Social Changes. Springer Tokyo, pp. 99-103.
Tapponnier, P., Molnar, P., 1979. Active faulting and Cenozoic tectonics of the Tien Shan,
Mongolia, and Baykal region. Journal of Geophysical Research 84, 3425-3459.
Tarasov, P.E., Bezrukova, E., Karabanov, E., Nakagawa, T., Wagner, M., Kulagina, N.,
Letunova, P., Abzaeva, A., Granoszewski, W., Riedel, F., 2007. Vegetation and climate
dynamics during the Holocene and Eemian interglacials derived from Lake Baikal
pollen records. Palaeogeography, Palaeoclimatology, Palaeoecology 252, 440-457.
Tarasov, P.E., Peyron, O., Guiot, J., Brewer, S., Volkova, V.S., Bezusko, L.G., Dorofeyuk,
N.I., Kvavadze, E.V., Osipova, I.M., Panova, N.K., 1999. Last Glacial Maximum
climate of the former Soviet Union and Mongolia reconstructed from pollen and plant
macrofossil data. Climate Dynamics 15, 227-240.
Tarasov, P.E., Volkova, V.S., Webb III, T., Guiot, J., Andreev, A.A., Bezusko, L.G.,
Bezosko, T.V., Bykova., G.V., Dorofeyuk, N.I., Kvavadze, E.V., Osipova, I.M.,
153
Panova, N.K., Sevastyanov, D.V., 2000. Last Glacial Maximum biomes reconstructed
from pollen and plant macrofossil data from northern Eurasia. Journal of Biogeography
27, 609-620.
Tian, F., Herzschuh, U, Dallmeyer, A., Xu, Q.H., Mischke, S., Biskaborn, B.K., 2013.
Environmental variability in the monsoon-westerlies transition zone during the last 1200
years: lake sediment analyses from central Mongolia and supra-regional synthesis.
Quaternary Science Reviews 73, 31-47.
Tian, F., Herzschuh, U., Telford, R.J., Mischke, S., Van der Meeren, T., Krengel, M., 2014. A
modern pollen-climate calibration set from central-western Mongolia and its application
to a late glacial-Holocene record. Journal of Biogeography 41, 1909-1922.
Torres, V., Vandenberghe, J., Hooghiemstra, H., 2005. An environmental reconstruction of
the sediment infill of the Bogotá basin (Colombia) during the last 3 million years from
abiotic and biotic proxies. Palaeogeography, Palaeoclimatology, Palaeoecology 226,
127-148.
Tucker, M.E., Wright, V.P., Dickson, J.A.D., 1990. Carbonate sedimentology. Blackwell
Scientific Publications, Oxford, pp. 284-292.
Tudhope, A.W., Chilcott, C.P., McCulloch, M.T., Cook, W.R., Chappell, J., Ellam, R.M.,
Lea, D.W., Lough, J.M., Shimmield, G.B., 2001. Variability in the El Niño-Southern
Oscillation through a Glacial-Interglacial cycle. Science 291, 1511-1517.
Újvári, G., Stevens, T., Svensson, A., Klötzli, U.S., Manning, C., Németh, T., Kovács, J.,
Sweeney, M.R., Gocke, M., Wiesenberg, G.L.B., Markovic, S.B., Zech, M., 2015. Two
possible source regions for Central Greenland last glacial dust. Geophysical Research
Letters, doi: 10.1002/2015GL066153.
Újvári, G., Varga, A., Raucsik, B., Kovács, J., 2014. The Paks loess-paleosol sequence: A
record of chemical weathering and provenance for the last 800 ka in the mid-Carpathian
Basin. Quaternary International 319, 22-37.
Van der Meeren, T., Verschuren, D., Ito, E., Martens, K., 2010. Morphometric techniques
allow environmental reconstructions from low-diversity continental ostracode
assemblages. Journal of Paleolimnology 44, 903-911.
Van Geel, B., Buurman, J., Brinkkemper, O., Schlelvis, J., Aptroot, A., Van Reenen, G.,
Hakbijl, T., 2003. Environmental reconstruction of a roman Period settlement site in
Uitgeest (Netherlands) with special reference to coprophilous fungi. Journal of
Archaeological Science 30, 873-883.
Vandenberghe, J., 2013. Grain size of fine-grained windblown sediment: A powerful proxy
for process identification. Earth-Science Reviews 121, 18-30.
Vandenberghe, J., Renssen, H., van Huissteden, K., Nugteren, G., Konert, M., Lu, H.Y.,
Dodonov, A., Buylaert, J.P., 2006. Penetration of Atlantic westerly winds into Central
and East Asia. Quaternary Science Reviews 25, 2380-2389.
Vanky, K., 1994. European smut fungi. Gustav Fischer Verlag, Stuttgart, New York.
154
Vassallo, R., Jolivet, M., Ritz, J.-F., Braucher, R., Larroque, C., Sue, C., Todbileg, M.,
Javkhlanbold, D., 2007. Uplift age and rates of the Gurvan Bogd system (Gobi-Altay)
by apatite fission track analysis. Earth and Planetary Science Letters 259, 333-346.
Vassallo, R., Ritzm J.-F., Carretier, S., 2011. Control of geomorphic processes on 10Be
concentrations in individual clasts: Complexity of the exposure history in Gobi-Altay
range (Mongolia). Geomorphology 135, 35-47.
Victor, R., Fernando, C.H., 1981. Ilyocypris dentifera Sars, 1903 versus Ilyocypris angulate
Sars, 1903. A taxonomic study of two species of Ilyocypris bradyi and Norman, 1889
(Crustacea, Ostracoda) described from China. Canadian Journal of Zoology 59, 1103-
1110.
Vogt, C., 1997. Regional and temporal variations of mineral assemblages in Arctic Ocean
sediments as climatic indicator during glacial/interglacial changes. Reports of Polar
Research 251, 1-309.
Von Eynatten, H., Barceló-Vidal, C., Pawlowsky-Glahn, V., 2003. Composition and
discrimination of sandstones: a statistical evaluation of different analytical methods.
Journal of Sedimentary Research 73, 47-57.
Von Eynatten, H., Tolosana-Delgado, R., Karius, V., 2012. Sediment generation in modern
glacial settings: Grain-size and source-rock control on sediment composition.
Sedimentary Geology 280, 80-92.
Vriend, M., Prins, M.A., 2005. Calibration of modelled mixing patterns in loess grain-size
distributions: an example from the north-eastern margin of the Tibetan Plateau, China.
Sedimentology 52, 1361-1374.
Walker, R.T., Nissen, E., Molor, E., Bayasgalan, A., 2007. Reinterpretation of the active
faulting in central Mongolia. Geology 35, 759-762.
Walker, R.T., Waugh, B., Grone, A.J., 1978. Diagenesis in first-cycle desert alluvium of
Cenozoic age, southern United States and northwestern Mexico. Geological Society of
America Bulletin 89, 19-32.
Walther, M., 1998. Paläoklimatische Untersuchungen zur jungpleistozänen
Landschaftsentwicklung im Changai-Bergland und in der nördlichen Gobi (Mongolei).
Petermanns Geographische Mitteilungen 142, 207-217.
Wang, G.X., Cheng, G.D., 1999. Water resource development and its influence on the
environment in arid areas of China – the case of the Hei River Basin. Journal of Arid
Environments 43, 121-131.
Wang, N.A., Li, Z.L., Cheng, H.Y., Li, Y., Huang, Y.Z., 2011. High lake levels on Alashan
Plateau during the Late Quaternary. Chinese Science Bulletin 56, 1367-1377.
Wang, W., Feng, Z.D., 2013. Holocene moisture evolution across the Mongolian Plateau and
its surrounding areas: A synthesis of climatic records. Earth-Science Reviews 122, 38-
57.
Wang, X.M., Xia, D.S., Zhang, C.X., Lang, L.L., Hua, T., Zhao, S., 2012. Geochemical and
magnetic characteristics of fine-grained surface sediments in potential dust source areas:
155
Implications for tracing the provenance of aeolian deposits and associated
palaeoclimatic change in East Asia. Palaeogeography, Palaeoclimatology,
Palaeoecology 323-325, 123-132.
Wang, Y.B., Liu, X.Q., Herzschuh, U., 2010. Asynchronous evolution of the Indian and East
Asian Summer Monsoon indicated by Holocene moisture patterns in monsoonal central
Asia. Earth-Science Reviews 103, 135-153.
Webb, L.E:, Johnson, C.L., 2006. Tertiary strike-slip faulting in southeastern Mongolia and
implications for Asian tectonics. Earth and Planetary Science Letters 241, 323-335.
Weltje, G.J., Tjallingii, R., 2008. Calibration of XRF core scanner for quantitative
geochemical logging of sediment cores: Theory and application. Earth and Planetary
Science Letters 274, 423-438.
Whitlock, C., Bartlein, P.J., 1997. Vegetation and climate change in northwest America
during the past 125 k. Nature 388, 57-61.
Williams, D.F., Peck, J., Karabanov, E.B., Prokopenko, A.A., Kravchinsky, V., King, J.,
Kuzmin, M.I., 1997. Lake Baikal record of continental insolation during the past 5
million years. Science 278, 1114-1117.
Windley, B.F., Allen, M.B., 1993. Mongolian plateau: evidence for a late Cenozoic mantle
plume under central Asia. Geology 21, 295-298.
Wirth, S.B., Gilli, A., Niemann, H., Dahl, T.W., Ravasi, D., Sax, N., Hamann, Y., Peduzzi,
R., Peduzzi, S., Tonolla, M., Lehmann, M.F., Anselmetti, F.S., 2013. Combining
sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past
water-column redox conditions: The example of meromictic Lake Cadagno (Swiss
Alps). Geochimica et Cosmochimica Acta 120, 220-238.
Wu, B.Y., Wang, J., 2002. Winter Arctic Oscillation, Siberian High and East Asian Winter
Monsoon. Geopgysical Research Letters 29, 1897, doi: 10.1029/2002GL015373.
Wünnemann, B., 1999. Untersuchungen zur paläohydrographie der endseen in der Badain
Jaran und Tennger Wüste, Innere Mongolei, Nordwest China. Habilitation Thesis, Freie
Universität Berlin, Berlin, Germany.
Wünnemann, B., Demske, D., Tarasov, P., Kotlia, B.S., Reinhardt, C., Bloemendal, J.,
Diekmann, B., Hartmann, H., Krois, J., Riedel, F., Arya, N., 2010. Hydrological
evolution during the last 15 k in the Tso Kar lake basin (Ladakh, India), derived from
geomorphological, sedimentological and palynological records. Quaternary Science
Reviews 29, 1138-1155.
Wünnemann, B., Hartmann, K., Altmann, N., Hambach, U., Pachur, H.-J., Zhang, H.C., 2007.
Interglacial and glacial fingerprints from lake deposits in the Gobi Desert, NW China.
In: Sirocko, F., Claussen, M., Sánchez-Goñi, M.F., Litt, T., (Eds.). The Climate of Past
Interglacials. Development in Quaternary Sciences 7, 323-347.
Wünnemann, B., Pachur, H.-J., 1998. Climatic and environmental changes in the deserts of
Inner Mongolia, China, since the Late Pleistocene. In: Alsharan, A.S., Glennie, K.W.,
Whittle, G.L., (Eds.). Quaternary Deserts and Climatic Change, Balkema, Rotterdam,
pp. 381-394.
156
Xiao, G.Q., Zong, K.Q., Li, G.J., Hu, Z.C., Dupont-Nivet, G., Peng, S.Z., Zhang, K.X., 2012.
Spatial and glacial-interglacial variations in provenance of the Chinese Loess Plateau.
Geophysical Research Letters 39, doi:10.1029/2012GL053304.
Xiao, J.L., Inouchi, Y., Kumai, H., Yoshikawa, S., Kondo, Y., Liu, T.S., An, Z.S., 1997.
Eolian quartz flux to Lake Biwa, central Japan, over the past 145,000 years. Quaternary
Research 48, 48-57.
Xiao, J.L., Xu, Q.H., Nakamura, T., Yang, X.L., Liang, W.D., Inouchi, Y., 2004. Holocene
vegetation variation in the Daihai Lake region of north-central China: a direct indication
of the Asian monsoon climatic history. Quaternary Science Reviews 23, 1669-1679.
Xu, X.K., Yang, J.Q., Dong, G.C., Wang, L.Q., Miller, L., 2009. OSL dating of glacier extent
during the Last Glacial and the Kanas Lake basin formation in Kanas River valley, Altai
Mountains, China. Geomorphology 112, 306-317.
Xu, Z.W., Lu, H.Y., Zhao, C.F., Wang, X.Y., Su, Z.Z., Wang, Z.T., Liu, H.Y., Wang, L.X.,
Lu, Q., 2011. Composition, origin and weathering process of surface sediment in
Kumtagh Desert, Northwest China. Journal of Geographical Sciences 21, 1062-1076.
Yancheva, G., Nowaczyk, N.R., Mingram, J., Dulski, P., Schettler, G., Negendank, J.F.W.,
Liu, J.Q., Sigman, D.M., Peterson, L.C., Haug, G.H., 2007. Influence of the
intertropical convergence zone on the East Asian Monsoon. Nature 445, 74-77.
Yang, X.P., Scuderi, L.A., 2010. Hydrological and climatic changes in deserts of China since
the late Pleistocene. Quaternary Research 73, 1-9.
Yang, B., Shi, Y.F., Braeuning, A., Wang, J.X., 2004. Evidence for a warm-humid climate in
arid northwestern China during 40-30 ka BP. Quaternary Science Reviews 23, 2537-
2548.
Yang, S.L., Ding, F., Ding, Z.L., 2006. Pleistocene chemical weathering history of Asian arid
and semi-arid regions recorded in loess deposits of China and Tajikistan. Geochimica et
Cosmochimica Acta 70, 1695-1709.
Yang, S.Y., Jung, H.-S., Li, C.X., 2004. Two unique weathering regimes in the Changjiang
and Huanghe drainage basins: geochemical evidence from river sediments. Sedimentary
Geology 164, 19-34.
Yang, X.P., Rost, K.T., Lehmkuhl, F., Zhu, Z.D., Dodson, J., 2004. The evolution of dry
lands in northern China and in the Republic of Mongolia since the Last Glacial
Maximum. Quaternary International 118/119, 69-85.
Yang, X.P., Scuderi, L.A., 2010. Hydrological and climatic changes in deserts of China since
the late Pleistocene. Quaternary Research 73, 1-9.
Yang, X.P., Scuderi, L., Paillou, P., Liu, Z.T., Li, H.W., Ren, X.Z., 2011. Quaternary
environmental changes in the drylands of China – A critical review. Quaternary Science
Reviews 30, 3219-3233.
Yang, X.P., Zhu, B.Q., White, P.D., 2007. Provenance of aeolian sediment in the Taklamakan
Desert of western China, inferred from REE and major-elemental data. Quaternary
International 175, 71-85.
157
Young, G., Nesbitt, H., 1998. Processes controlling the distribution of Ti and Al in
weathering, siliciclastic sediments and sedimentary rocks. Journal of Sedimentary
Research 68, 448-455.
Yu, G., Cui, F., Shi, Y.F., Zheng, Y., 2007. Late marine isotope stage 3 paleoclimate for East
Asia: a data-modal comparison. Palaeogeography, Palaeoclimatology, Palaeoecology
250, 167-183.
Yu, K.F., Hartmann, K., Nottebaum, V., Stauch, G., Lu, H.Y., Zeeden, C., Yi, S.W.,
Wünnemann, B., Lehmkuhl, F., 2016. Discriminating sediment archives and
sedimentary processes in the arid endorheic Ejina Basin, NW China using a robust
geochemical approach. Journal of Asian Earth Sciences 119, 128-144.
Yu, K.F., Lehmkuhl, F., Falk, D., 2017. Quantifying land degradation in the Zoige Basin, NE
Tibetan Plateau using satellite remote sensing data. Journal of Mountain Science 14, 77-
93.
Yu, K.F., Lu, H.Y., Lehmkuhl, F., Nottebaum, V., 2013. A preliminary quantitative
paleoclimate reconstruction of the dune fields of northern China during the Last Glacial
Maximum and Holocene optimum. Quaternary Sciences 33, 293-302.
Yu, Z.T., Liu, X.Q., Wang, Y., Chi, Z.Q., Wang, X.J., Lan, H.Y., 2014. A 48.5-ka climate
record from Wulagai Lake in Inner Mongolia, Northeast China. Quaternary
International 333, 13-19.
Zhai, D.Y., Xiao, J.L., Zhou, L., Wen, R.L., Chang, Z.G., Pang, Q.Q., 2010. Similar
distribution pattern of different phenotypes of Limnocythere inopinata (Baird) in a
brackish-water lake in Inner Mongolia. Hydrobiologia 651, 185-197.
Zhai, X.W., 2008. The Holocene climate and environment changes in the Mongolian Plateau.
Dissertation to Lanzhou University, Lanzhou.
Zhang, C.J., Zhang, W.Y., Feng, Z.D., Mischke, S., Gao, X., Gao, D., Sun, F.F., 2012.
Holocene hydrological and climatic change on the northern Mongolian Plateau based on
multi-proxy records from Lake Gun Nuur. Palaeogeography, Palaeoclimatology,
Palaeoecology 323-325, 75-86.
Zhang, H.C., Ming, Q.Z., Lei, G.L., Zhang, W.X., Fan, H.F., Chang, F.Q., Wünnemann, B.,
Hartmann, K., 2006. Dilemma of dating on lacustrine deposits in a hyperarid inland
basin of NW China. Radiocarbon 48, 219-226.
Zhang, Y.Y., 2014a. Robustfa: An object oriented solution for robust factor analysis. R
Package Version 1.0-5. http://CRAN.R-project.org/package=robustfa.
Zhang, Y.Y., Pe-Piper, G., Piper, D.J.W., 2014b. Sediment geochemistry as a provenance
indicator: Unrevealing the cryptic signatures of polycyclic sources, climate changes,
tectonism and volcanism. Sedimentology 61, 383-410.
Zhao, J.D., Yin, X.F., Harbor, J.M., Lai, Z.P., Liu, S.Y., Li, Z.Q., 2013. Quaternary glacial
chronology of the Kanas River valley, Altai Mountains, China. Quaternary
International 311, 44-53.
158
Zhao, Y., Yu, Z.C., Chen, F.H., Li, J.J., 2008. Holocene vegetation and climate change from a
lake sediment record in the Tengger Sandy Desert, northwest China. Journal of Arid
Environments 72, 2054-2064.
Zhao, Y., Liu, H.Y., Li, F.R., Huang, X.Z., Sun, J.H., Zhao, W.W., Herzschuh, U., Tang, Y.,
2012. Application and limitations of the Artemisia/Chenopodiaceae pollen ratio in arid
and semi-arid China. The Holocene 22, 1385-1392.
Zhu, B.Q., Yu, J.J., Rioual, P., Gao, Y., Zhang, Y.C., Min, L.L., 2014. Geomorphoclimatic
characteristics and landform information in the Ejina Basin, Northwest China.
Environmental Earth Sciences, doi: 10.1007/s12665-014-3927-9.
159
Appendix
Tab. A1: Ratios from major elements to oxides and corresponding functions.
Oxides Name Ratios
Na2O Sodium Oxide 1.3480
MgO Periclase 1.6583
Al2O3 Corundum 1.8895
SiO2 Quartz 2.1393
P2O5 Phosphorus Pentoxide 2.2914
K2O Potassium Oxide 1.2046
CaO Calcium Oxide 1.3992
TiO2 Rutile 1.6685
MnO Manganosite 1.2912
Fe2O3 Hematite 1.4297
𝑏𝑛 = 𝑎𝑛 ∗ r𝑛/104 Eq. (A.1)
𝑏𝑛′ = 𝑏𝑛 ∗ 100/ ∑ 𝑏𝑛
10𝑛=1 Eq. (A.2)
In Eq. (A.1), a denotes original major elements abundance in ppm. b denotes oxide data. r is ratio in
above table. n ranges from 1 to 10, i.e., ten major elements. respectively. In Eq. (A.2), bn’ is the
normalized oxides in wt %, which is used in the multivariate statistics.
160
R script employed in the dissertation
# this script is part of the manuscript ‘Discriminating sediment archives and sedimentary
processes in the arid endorheic Ejina Basin, NW China using a robust geochemical approach'
by Yu et al. in Journal of Asian Earth Science, and manuscript ‘Geochemical imprints of
coupled paleoenvironmental and provenance change in the lacustrine sequence of Orog Nuur,
Gobi Desert of Mongolia’ by Yu et al.
# load the 'boot' package, which must be installed
library(boot)
library(Hmisc)
# read in element data from clipboard, as in S3.
data<-read.table("clipboard",dec=",",header=TRUE,sep='\t')
# row names of archive types and sequence number
names1<-
c("A1","L1","F1","A2","A3","A4","A5","A6","A7","A8","A9","A10","A11","A12","A13","
A14","A15","F2","L2","A16","A17","A18","A19","A20","A21","L3","L4","A22","A23","A2
4","A25","A26","A27","A28","A29","F18","L5","A30","A31","A32","G1","G2","L6","L7","
L8","L9","F3","F4","F5","F6","A33","L10","S1","F7","L11","S2","L12","L13","F8","F9","L
14","L15","F10","L16","L17","F11","F12","A34","F13","F14","F15","F16","F17","A35","A
36","A37","A38","L18","L19","A39","A40","A41","A42","G3","A43","A44","A45","A46","
A47","A48","A49","A50","A51")
# column names of elements (raw data set)
names2<-
c("Na","Mg","Al","Si","P","K","Ca","Mn","Fe","Ti","S","Cl","V","Cr","Ni","Cu","Zn","Ga",
"As","R
b","Sr","Y","Zr","Nb","Ba","Nd","Hf","W","Pb","Th")
rownames(data)=make.names(names1,unique=TRUE)
colnames(data)=make.names(names2)
data # shows the data matrix with specific row names
# read in grain size AND element data from clipboard, as in S3.
data_all<-read.table("clipboard",dec=",",header=FALSE,sep='\t',stringsAsFactors = FALSE)
data_all <- do.call(rbind, data_all)
data_all2 <- apply(data_all, 1,as.numeric)
data_all2 <- t(as.numeric(data_all))
#[R,P] = corr(data_all, data_all)
Cor<-rcorr(data_all2) # generate correlation matrix and corresponding P values
dlmwrite('R1.txt',Cor$r)
dlmwrite('P1.txt',P) # imported into Excel>>R<-read.table("clipboard")
161
P<-read.table("clipboard")
mysub<-function(x){sub(",",".",x)} # create an function to replace "," with "."
dataR<-(apply(R,2,mysub))
R1<-data.frame(apply(dataR,2,as.numeric)) #change the matrix as numeric
dataP<-(apply(P,2,mysub))
P1<-data.frame(apply(dataP,2,as.numeric))
R<-R1
P<-P1
data_matrix<-(R)
data_matrix2<-matrix(nrow=length(P),ncol=length(P))
for(C in 1:40) # 40 can be dim(data[40])
{
for(Ro in 1:40)
{
if(P[Ro,C]<0.05){data_matrix2[Ro,C]<-data_matrix[Ro,C]}
# set criterion: P<0.05, can be set different, criterion here, >.5, this need to be improved later
}}
data_heatmap<-
heatmap(data_matrix2,Rowv=NA,Colv=NA,col=topo.colors(256),scale="column",margins=c
(5,10))>
install.packages("lattice")
library(lattice)
levelplot(data_matrix2,col.regions=topo.colors(256))
circle<-function(center=c(0,0),npoints=100){r=1
+ tt=seq(0,2*pi,length=npoints)
+ xx=center[1]+r*cos(tt)
+ yy=center[1]+r*sin(tt)
+ return(data.frame(x=xx,y=yy))
+ }
corcir=circle(c(0,0),npoints=100)
loadings_16<-as.data.frame(vRFs)
arrows=data.frame(x1=c(0,0,0,0),y1=c(0,0,0,0),x2=loadings_16$vRF1,y2=loadings_16$vRF
2)
ggplot()
+geom_path(data=corcir,aes(x=x,y=y))
+geom_segment(data=arrows,aes(x=x1,y=y1,xend=x2,yend=y2))
162
+geom_text(data=loadings_16,aes(x=vRF1,y=vRF2,label=rownames(loadings_16)))+geom_h
line(yint
ercept=0)
+geom_vline(xintercept=0)
+labs(x="Robust Factor 1",y="Robust Factor 2")
+ggtitle("Loadings Plot") # loadings plot for robust data
>robustfa_30<-
factorScorePfa(sum,factors=4,covmat=covwt,cor=TRUE,rotation="varimax",scoresMethod=c
("regres
sion")
>rownames(robustfa_30$loadings)=make.names(names2,unique=TRUE)
>scores_30=as.data.frame(robustfa_30$scores)
>ggplot(data=scores_30,aes(x=Factor1,y=Factor2,label=rownames(scores_30)))+geom_hline
(yinterce
pt=0)+geom_vline(xintercept=0)+geom_text(colour="tomato",alpha=0.8,size=4)+ggtitle("Sc
ores
Plot") # scores plot
>arrows_30=data.frame(x1=c(0,0),y1=c(0,0),x2=loadings_30$RF1_30,y2=loadings_30$RF2
_30)
>ggplot()+geom_path(data=corcir,aes(x=x,y=y))+geom_segment(data=arrows_30,aes(x=x1,y
=y1,xen
d=x2,yend=y2))+geom_text(data=loadings_30,aes(x=RF1_30,y=RF2_30,label=rownames(lo
adings_3
0)))+geom_hline(yintercept=0)+geom_vline(xintercept=0)+labs(x="Robust Factor
1",y="Robust
Factor 2")+ggtitle("Loadings Plot") # loadings plot for raw data
>RF1<-robustfa_16$scores[,1]
>RF2<-robustfa_16$scores[,2]
>labs_robustfa<-rownames(robustfa_16$scores)
>RF_scores<-data.frame(cbind(RF1,RF2))
>rownames(RF_scores)<-labs_robustfa
>ggplot(RF_scores,aes(RF1,RF2,label=rownames(RF_scores)))+geom_text()
>scores_16=as.data.frame(robustfa_16$scores)
>ggplot(data=scores_16,aes(x=Factor1,y=Factor2,label=rownames(scores_16)))+geom_hline
(yinterce
pt=0)+geom_vline(xintercept=0)+geom_text(colour="tomato",alpha=0.8,size=4)+ggtitle("Sc
ores
Plot") # scores plot for robust data
163
Acknowledgements
In 2012, the author got the chance to visit RWTH and started in 2013 with PhD works here. It
is great honor to spend three years’ time in Aachen to pursue knowledge concerning past
environmental changes and mechanisms. The author extends his sincere thanks to the
financial support from German Academic Exchange Service (DAAD) and China Scholarship
Council (CSC) through the Master and PhD studies. On the other hand, words cannot express
gratitude for all the support from advisor Prof. Frank Lehmkuhl, institute, colleagues, friends
and family members. So many people have contributed to the accomplishment of the
dissertation, making it seems impossible to name all. The author specially thanks:
The RWTH group:
First, the author want to express his deep grateful to advisor, Prof. Frank Lehmkuhl,
who make it possible for this PhD work and provides freedom to follow the author’s
own ideas and the training opportunities in summer schools, workshops and
conferences; the author also thanks Mrs. Carola Lehmkuhl, for the delicious food
during every year’s Christmas and nice memories of watching matches in the Stadium-
Tivoli of Alemannia Aachen;
Thanks for the accompanying through the field, lab works, manuscripts
writing/revision and daily life from Dr. Veit Nottebaum, Dr. Georg Stauch, Dr. David
Loibl, Dr. Christian Zeeden, Igor Obreht, Philipp Schulte, and Dr. Andreas
Rudersdorf; the author acknowledge deep grateful to Prof. Wolfgang Römer, Dr.
Martin Knippertz, Prof. Christoph Hilgers, Prof. Klaus Reicherter, Prof. Eileen
Eckmeier, Marianne Dohms, Lydia Krauß, Janina Bösken, Mona Ziemes, Anja Knops,
Verena Niedek, Isabel Pipaud, Bernhard Pröschel, Jörg Zens, Michael Buchty-Lemke,
for their kind help during the PhD works;
The author sincerely appreciate Dr. Eva Huintjes, Bastian Paas, Isabell Maras, René
Delpy, Dimitri Falk, Vera Schleiden, Annika Hörstmann-Jungemann, Matthias
Mensing, René Kocgazi, Gernot Frommelt, Hans-Joachim Ehrig and Dr. Gunnar
Ketzler, for accompanying in the Mensa, party and beer drinking.
The AWI group:
Prof. Berhard Diekmann has kindly supervised the PhD work regarding the bulk-
geochemistry in the lacustrine realm and corresponding paleoenvironmental
implications; Stefan Schimpf offered geological mapping of the Gaxun Nuur Basin.
The Mainz group:
Prof. Jörg Grunert has kindly provided his rich experience concerning the
geomorphological characteristics in the Valley of Gobi Lakes, Mongolia and the Gobi
Desert, and reviewed manuscripts about the Orog Nuur drilling core.
The Nanjing group:
The author’s Master advisor Prof. Huayu Lu, Prof. Bernd Wünnemann, Chuanbing
Yang and Shuangwen Yi have kindly supported and organized the OSL dating in
Nanjing lab and manuscripts writing/revision.
The Berlin group:
Dr. Kai Hartmann provides state-of-art techniques concerning the multivariate
statistics; J. Bölscher has kindly mailed the HC8 sediment samples; Dr. Gregori
Lockot provides vital information regarding reservoir effects in the lacustrine realm.
164
The NIHK/Göttingen group:
Dr. Frank Schlütz and Dr. Waheed Murad have kindly conducted the palynological
analysis and helped with the manuscript writing and revision, rendering the possibility
and the outline of the dissertation.
The Reykjavík/Potsdam group:
Prof. Stefan Mischke has conducted ostracod analysis in the dissertation and offered
pivotal experiences about scientific editing and reviewing.
The Wisconsin group:
Prof. Joseph Mason provides significant comments about the oral talk during the EGU
2016 and has kindly reviewed the manuscript.
The Xi’an group:
Prof. Youbin Sun has kindly reviewed the manuscript and offered helpful comments
during the INQUA 2015.
The Xining/Wuhan group:
Prof. Zhongping Lai provides significant remarks concerning the first manuscript
during the 2014 workshop in Nanjing.
The Vienna group:
Prof. Peter Filzmoser has kindly helped with the R scripts programming and
multivariate statistics.
Conferences and workshops:
ICAR VIII 2014: Prof. Jef Vandenberghe, Prof. Xiaoping Yang, Dr. Jan-Berend
Stuut, Dr. Jianbao Liu, Dr. Runqiang Zeng, Shibo Tuo, Dr. Zhiwei Xu, Han Feng,
Mengchun Cui, Dr. Yali Zhou and Prof. Hanchao Jiang provided pivotal remarks
concerning the oral talk and accompanied the impressive excursion to the Tengger
Desert;
AK Wüstenrandforschung 2014: Andrea Junge, Dr. Johanna Lomax provided their
interesting experiences regarding OSL dating in arid realm and its combination with
archaeological studies in the Middle East;
INQUA 2015: Prof. Zhaodong Feng, Prof. Jule Xiao, Prof. Slobodan Marković, Dr.
Sumiko Tsukamoto, Dr. Thomas Stevens, Dr. Jingran Zhang, Dr. Xiaozhong Huang
and Dr. Xin Jia has provided kindly comments regarding the oral talk and manuscripts;
And the author would like to express special thanks to Prof. Zhaodong Feng, for his
kind offering the book that reviews his career’s work in Mongolia: “Vegetation
changes and associated climate variations in the Mongolian Plateau during the past
40,000 years”;
2015 TPE & TiP Science & Technology Training School: Prof. Fan Zhang, Prof.
Erwin Appel, Prof. Antje Schwalb, Prof. Shichang Kang, all the lecturers and
classmates have given a unforgettable experiences in Alpine ecosystem and the
Yulong Glacier; the author especially thank the financial support from the German
Research Foundation (DFG) and Chinese Academy of Science (CAS);
Junge Geomorphologen 2015: Julia Meister, Dr. Sabine Kraushaar, Dr. Jan Blöthe,
Raphael Steup and Simon Meyer-Heintze have kindly helped the oral talk and
provided useful suggestions concerning the first manuscript;
165
EGU 2016: It my first time to take part in such sort of wide range subject conference,
Prof. Dominik Fleitmann, Prof. Markus Fuchs, Prof. Hans von Suchodoletz, Prof.
Achim Brauer, Prof. Fahu Chen, Prof. Xiaohua Gou and Dr. Gaojun Li have greatly
helped concerning the oral talk and manuscript revision; Special thanks are given to
the accompanying friends: Igor Obreht, Lydia Krauß, Janina Bösken and Han Feng;
As well, the author express his sincere thanks to the financial support from the AK
Geomorphologie (Prof. Markus Fuchs, Der Deutsche Arbeitskreis für
Geomorphologie);
USSP 2016 & ECORD Training Course 2017 (MARUM): Thanks Prof. Frank
Lehmkuhl, Dr. Christian Zeeden, and Igor Obrecht for the supporting to attend the
outstanding summer school and training courses about the state-of-the-art of the
coupled paleobiogeochemistry and climate modelling. It really extends the author’s
knowledge to a brand new level regarding the Cenozoic scale climate change and
proxies interpretations.
For the manuscripts:
Acknowledgements for the manuscript: “Discriminating sediment archives and
sedimentary processes in the arid endorheic Ejina Basin, NW China using a
robust geochemical approach” (Chapter 4): The study was funded by German
Federal Ministry of Education and Research (BMBF-CAME: 03G0814A), National
Natural Science Foundation of China (41371203, 41321062) and China Scholarship
Council (201306190112). Dr. C. Zeeden is supported by German Research Foundation
(DFG: SFB806). We gratefully thank Prof. C. Hilgers, Prof. W. Römer, I. Obreht, A.
Rudersdorf, P. Schulte, G. Lockot, N. Herrmann, S. Schimpf, Dr. D. Loibl, Dr. S.
Kraushaar and Dr. E. Eckmeier for constructive discussions about the methodology
and manuscript, Prof. Z.-P. Lai, Prof. F.-H. Chen, and Prof. K. Reicherter contributed
to the discussion. Prof. P. Filzmoser helped with the R calculation. J. Bölscher offered
the data of HC8 section, colleagues from Nanjing Uni., FU Berlin, AWI Potsdam and
Lanzhou Uni. helped during the field investigation, M. Dohms and C.-B. Yang are
acknowledged for parts of Lab work. Anonymous reviewers are sincerely appreciated
for improving the manuscript.
Acknowledgements for the manuscript: “Lake sediments documented late
Quaternary humid pulses in the Gobi Desert of Mongolia: Vegetation, hydrologic
and geomorphic implications” (Chapter 5): This study was funded by the German
Research Foundation (LE 730/16-1: Late Pleistocene, Holocene and ongoing
geomorpho-dynamics in the Gobi Desert, South Mongolia) and China Scholarship
Council (201306190112). The fieldwork was supported by the Institute of Geography
of the Mongolian Academy of Science (Prof. D. Dorjgotov, A. Tschimegsaichan). Dr.
T. Felauer, Dr. A. Hilgers and Dr. D. Hülle helped the field work. Palynological
analysis and radiocarbon dating were financed by a scholarship issued to Dr. W.
Murad. I. Pipaud offered the base map for geologic mapping. Prof. H. Rother offered
information concerning the paleoglaciation in the Khangai Mountains. We sincerely
appreciate the constructive discussions with Prof. F.-H. Chen, Prof. D. Fleitmann,
Prof. H.J. Spero, Prof. G.R. Dickens, Dr. S.R. Meyers, Prof. H.-Y. Lu, Prof. J.A.
Mason, Prof. Z.-D. Feng, Prof. J.-L. Xiao, I. Obreht, P. Schulte, Dr. C. Zeeden, Dr. F.
Muschitiello and Dr. J.-B. Liu during the INQUA 2015, EGU 2016 and USSP 2016.
Acknowledgments for the manuscript: “Geochemical imprints of coupled
paleoenvironmental and provenance change in the lacustrine sequence of Orog
Nuur, Gobi Desert of Mongolia” (Chapter 6): This study was funded by the German
Research Foundation (LE 730/16-1) and China Scholarship Council (201306190112).
166
Fieldwork was supported by the Institute of Geography of the Mongolian Academy of
Sciences (D. Dorjgotov, A. Tschimegsaichan). Radiocarbon dating was financed by a
scholarship issued to W. Murad. I. Pipaud helped with the geologic mapping. F.
Schlütz and T. Felauer supported the field work. We sincerely appreciate the
constructive discussion with S. Mischke, J. Grunert, F.H. Chen, A.C.G. Henderson,
H.Y. Lu, Z.D. Feng, J.L. Xiao, D. Fleitmann, P. Schulte, and I. Obreht during the
INQUA 2015 and EGU 2016. T.J. Whitmore, C. Zhao, M. Brenner, M. Riedinger-
Whitmore, and two anonymous reviewers are sincerely appreciated for improving the
manuscript.
Also, special thanks to friends who have visited the author during these three years: Dr.
Wentao Yang, Ning Ma, Tao Chen, Achyut Tiwari, Dr. Xianyan Wang, Hanzhi Zhang, Simon
Wittich and Chi Zhang. Thanks for the accompanying of Miaoqun Yin, Zhengxin Pu and
Nian Zhang. In the end, the author wants to acknowledge debt to his parents Zhongxiang Yu,
Lanying Zhang, dear Chathrin and kinsfolk, without whose support, assistance and patience,
this endeavor would not have been possible.
167
Abstract
Considerable efforts have been devoted to disentangle the late Quaternary moisture and
thermal evolution of arid central Asia. However, an array of paramount aspects has inhibited
our complete understanding of the broad pattern of Quaternary moisture and thermal history
of arid central Asia and underlying mechanisms.
The Ejina Basin, with its suite of different sediment archives, is known as one of the main
sources for the loess accumulation on the Chinese Loess Plateau. In order to understand
mechanisms along this supra-regional sediment cascade (aeolian, fluvial and alluvial
sediments), it is crucial to decipher the archive characteristics and formation processes. Five
sediment archives from three lithologic units exhibit geochemical characteristics as follows:
(i) aeolian sands have high contents of Zirconium and Hafnium, whereas only Hafnium can be
regarded as a valuable indicator to discriminate the coarse sand proportion; (ii) sandy loess
has high Calcium and Strontium contents which both exhibit broad correlations with the
medium to coarse silt proportions; (iii) lacustrine clays have high contents of felsic,
ferromagnesian and mica source elements e.g., Potassium, Iron, Titanium, Vanadium, and
Nickel; (iv) fluvial sands have high contents of Magnesium, Chlorine and Sodium which may
be enriched in evaporite minerals; (v) alluvial gravels have high contents of Chromium which
may originate from nearby Cr-rich bedrock. Temporal variations can be illustrated by four
robust factors: weathering intensity, silicate-bearing mineral abundance, saline / alkaline
magnitude and quasi-constant aeolian input. In summary, the bulk-composition of the late
Quaternary sediments in this arid context is governed by the nature of the source terrain, weak
chemical weathering, authigenic minerals, aeolian sand input, whereas pedogenesis and
diagenesis exert only limited influences. Hence, here demonstrates a practical geochemical
strategy to discriminate sediment archives and thereafter enhance our ability to offer more
intriguing information about the sedimentary processes in the arid central Asia.
On the other hand, two parallel cores (ONW I, 6.00 m; ONW II, 13.35 m) were retrieved from
lake Orog Nuur, in the Gobi Desert of Mongolia. Ample evidences reveal a marked moisture
pulse during the Marine Isotope Stage 3 (~36-~24 ka) which might have induced the
maximum last glacial expansion in the high elevated Khangai Mountains. A sharp transition
of Termination I (~11 ka) is illuminated by geochemical, palynological, and ostracod data.
Lower area of the Orog Nuur catchment was dominated by Artemisia steppe community in
the late Pleistocene and altered gradually to Chenopodiaceae desert steppe in the Holocene.
The early Holocene is also characterized by relatively humid environment, albeit discordant
168
downcore variability of moisture and thermal signals can be derived between palynological
and bulk-geochemical signals. Water body in the Holocene appears to be a distinct alkaline
environment which was subjected to frequent allogenic input and disturbance of the late
Pleistocene anoxic states. These two humid pulses may be the trait of a larger scale of arid
central Asia that would be documented in a suite of archives. Considering kinetics, a coupled
atmospheric component comprising both East Asian Summer Monsoon and strengthened
Westerlies moisture supply seems to be the driving mechanism, and this coupled mode might
have been modulated broadly by boreal insolation variances. On the other hand, four major
harsh climatic phases were documented in the core at ~47 ka, ~37 ka, ~19 ka (gLGM) and
~13-~11 ka (Younger Dryas) as playa phases. Reduced conveying of the Westerlies moisture
along with the retreated East Asian Summer Monsoon might have contributed to these playa
phases in the Gobi Desert.
Continuous, high-resolution elemental abundances at a 1 cm interval were examined on core
ONW II. Due to the predominant clay or silty-clay fraction in the sediments, Aluminium and
Silicon display broadly identical pattern. Calcium behaviors may be ascribed to the authigenic
calcite variance. Manganese and Cobalt act as sound indicator for the redox condition. Owing
to the short burial time and weak diagenetic influence, Iron is not an indicator to the
diagenetic processes. Likewise, Zirconium may be associated to fluvial clastic in relation to
the lithotypes but not necessarily linked to the aeolian sands relative to that in the pelagic
realm. Furthermore, Sulfur in lake sediments may denote the redox condition and Potassium
is more likely linked to the K-feldspar which is associated with the allogenic fluvial inputs.
The two sand layers corresponding to LGM and YD event were dominated by coarse sands.
In the Gobi Desert of Mongolia, these two laminations provide an opportunity to be regarded
as potential chronological benchmarks. As inferred from the biplot between Ca and Al/Si,
disparate source lithotypes may exist before and after Termination I. The Holocene appears to
be a distinct alkaline environment compared with the late Pleistocene. This may be ascribed to
strengthened fluvial morphodynamics of the riverine inflows and intensified erosion of source
rocks in the upper catchment of the Orog Nuur. In exceptionally arid realm, sands may exert
significant influence on bulk-geochemistry of the lake sediments. In summary, considering
the bulk-geochemistry of lacustrine sediments, paleoclimate would not be the solely
governing factor, the coupled alteration of precursor rocks and decomposition intensity may
also exert pivotal influences.
169
Zusammenfassung
Beachtliche Versuche sind unternommen worden, um die hygrische und thermische
Entwicklung des ariden Zentralasiens im Spätquartär zu entschlüsseln. Allerdings sind das
allgemeine Schema der hygrischen und thermischen Entwicklung des ariden Zentralasiens im
Quartär sowie die zugrundeliegende Mechanismen noch nicht umfassend verstanden.
Das Ejina-Becken in der Inneren Mongolei (China) hat unterschiedliche Sedimentarchive und
ist als eine der Hauptquellen für die Lössakkumulation auf dem Chinesischen Lössplateau
bekannt. Um die Mechanismen entlang der überregionalen Sedimentkaskaden zu verstehen,
ist es notwendig, die Archiveigenschaften und Bildungsprozesse zu entschlüsseln. Um diese
Fragen zu beantworten wurden fünf Profile in unterschiedlichen geomorphologischen
Kontexten ausgewählt. Die Untersuchungsergebnisse zeigen, dass die fünf Sedimentarchive
aus drei lithologischen Einheiten folgende geochemische Charakteristika aufweisen: (i)
äolische Sande haben höhere Zirconium- und Hafnium-Gehalte, wobei nur Hafnium als
verwertbarer Indikator für den Grobsandanteil betrachtet werden kann; (ii) sandiger Löss hat
höhere Kalzium- und Strontium-Gehalte, welche beide eine deutliche Korrelation mit Mittel-
und Grobschluffanteilen aufweisen; (iii) lakustrische Tone haben höhere Gehalte an
felsischen, ferromagnesiumhaltigen und Glimmer-Ausgangselementen, wie z.B. Kalium,
Eisen, Titan, Vanadium, und Nickel; (iv) fluviale Sande haben höhere Magnesium-, Chlor-
und Natrium-Gehalte, welche in Evaporitmineralen angereichert sein können; (v) alluviale
Kiese haben höhere Chrom-Gehalte, welche von nahe gelegenen Chrom-reichen Gestein
stammen könnten. Zeitliche Variationen können anhand von vier Faktoren veranschaulicht
werden: Verwitterungsintensität, Anteil an Silikathaltigen Mineralien, salzhaltiger Magnitude
und Ausmaß an quasi-konstantem äolischem Eintrag. Zusammenfassend kann festgehalten
werden, dass die Zusammensetzung der Sedimente aus dem späten Quartär in diesem ariden
Kontext durch die Reliefbedingungen der Sedimentquelles, durch eine schwache chemische
Verwitterung, authigener Minerale sowie äolischen Sandeintrags bestimmt werden.
Pedogenese und Diagenese üben nur einen geringen Einfluss aus.
Zwei parallele Kernbohrungen (ONW I, 6.00 m; ONW II, 13.35 m) vom Orog Nuur (Nuur =
See) See in der Gobi Wüste der Mongolei wurden näher analysiert. Es gibt viele Belege für
einen ausgeprägten Feuchtigkeitsimpuls während des marinen Isotopenstadiums 3 (MIS 3;
~36-~24 ka), welcher auch den maximalen letztglazialen Eisvorstoß im Khangai Gebirge
hervorgerufen haben könnte. Ein scharfer Übergang am Ende der letzten Eiszeit (~11 ka) wird
mittels geochemischen, palynologischen und Ostrakodendaten nachgewiesen. Das untere
170
Einzugsgebiet des Orog Nuur war im Pleistozän durch Artemisia Steppengesellschaften
dominiert und veränderte sich im Holozän allmählich zur Chenopodiaceae-Wüstensteppe. Das
frühe Holozän ist ebenso durch eine relativ feuchte Umwelt gekennzeichnet, wenn auch eine
gegenläufige Variabilität der hygrischen und Temperatursignale zwischen den
palynologischen und gesamt-geochemischen Signalen abgeleitet werden können. Der
holozäne Wasserkörper zeigt alkalische Bedingungen und war häufig allochthonen
Sedimenteinträgen sowie höherer limnischer Sauerstoffzufuhr als im späten Pleistozän
ausgesetzt. Dadurch wurden Phasen anoxischer Bedingungen im See verringert. Die zwei
genannten Feuchteimpulse könnten ein weit verbreitetes Phänomen im trockenen Zentralasien
sein, welches in zahlreichen Archiven dokumentiert wurde. Betrachtet man die
atmosphärische Kinetik, scheinen die gekoppelten atmosphärische Phänomene des
Ostasiatischen Sommermonsuns (East Asian Summer Monsoon; EASM) und eine verstärkte
Feuchtigkeitzufuhr durch die Westwinde die treibenden Mechanismen zu sein. Diese
gekoppelte Funktionsweise könnte durch die Schwankungen der Solareinstrahlung in borealen
Breiten moduliert worden sein. Des Weiteren wurden in den Bohrkernen vier aride Phasen,
repräsentiert durch Playa-Phasen, nachgewiesen: Um ~47 ka, ~37 ka, ~19 ka (gLGM) und
~13-~11 ka (Jüngere Dryas). Der geringere Feuchtetransport über die Westwinde sowie ein
abgeschwächter Ostasiatischer-Monsun könnte zur Ausprägung dieser Playa-Phasen
beigetragen haben.
Kontinuierliche, hochauflösende Elementhäufigkeiten wurden in 1 cm-Intervallen im
Bohrkern ONW II untersucht. Aufgrund der vorherrschenden Ton- oder schluffigen
Tonfraktion in den Sedimenten, zeigen Aluminium und Silizium weitgehend ein identisches
Muster. Die Verhaltensweisen von Kalzium können auf die Varianz des authigenen Kalzits
zurückgeführt werden. Mangan und Kobalt fungieren als aussagekräftige Indikatoren für
Redoxbedingungen. Wegen der kurzen Überdeckungszeit und der schwachen diagenetischen
Überprägung ist Eisen kein Indikator für die diagenetischen Prozesse. Zirkon kann
wahrscheinlich mit den fluvialen Sedimenten in Verbindung gebracht werden, wenn man sich
auf die Deckgesteine bezieht. Nicht aber notwendigerweise mit den äolischen Sanden.
Darüber hinaus könnte das Vorkommen von Schwefel in Seesedimenten die Redoxbedingung
anzeigen. Kalium ist eher mit K-Feldspat verknüpft, was mit allochthonen fluvialen Einträgen
in Zusammenhang gebracht werden kann. Die zwei mit dem letztglazialen Kältemaximum
(LGM) und der Jüngeren Tundrenzeit (YD = Younger Dryas) - Ereignissen einhergehenden
Sandschichten, werden durch grobkörnige Sande in den Bohrkern angezeigt. Wie aus dem
Biplot zwischen Ca und Al/Si abgeleitet werden kann, kommen unterschiedliche sedimentäre
171
Oberflächen als Quellen der lakustrinen Ablagerungen vor und nach dem Ende des
Pleistozäns in Frage. Im Holozän scheint im Vergleich zum späten Pleistozän ein deutlich
alkalisches Seesystem vorzuherrschen. Darauf deuten eine verstärkte fluviale
Morphodynamik und effektivere Erosion in den oberen Einzugsgebieten des Orog Nuur
während des frühen Holozäns hin. In ariden Gebieten, können Sande einen signifikanten
Einfluss auf die Gesamt-geochemie der Seesedimente ausüben. Zusammenfassend kann
festgehalten werden, dass angesichts der Gesamt-geochemie lakustrischer Sedimente, das
Paläoklima nicht der einzig bestimmende Faktor sein muss, sondern die Kopplung der
Einflüsse von Ausgangsgesteinen und die Verwitterungsintensität ebenso entscheidenden
Einfluss haben.