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Quaternary Geochronology

journal homepage: www.elsevier .com/locate/quageo

Research paper

OSL dating of fine and coarse quartz from a Palaeolithic sequence onthe Bistrița Valley (Northeastern Romania)

O. Trandafir a, b, A. Timar-Gabor a, d, *, C. Schmidt c, D. Veres a, d, f, M. Anghelinu e,U. Hambach c, S. Simon a, b

a Interdisciplinary Research Institute on Bio-Nano-Science of Babes-Bolyai University, Treboniu Laurean 42, 400271 Cluj-Napoca, Romaniab Faculty of Physics, Babes-Bolyai University, M. Kog�alniceanu 1, 400084 Cluj-Napoca, Romaniac Chair of Geomorphology, University of Bayreuth, 95440 Bayreuth, Germanyd Faculty of Environmental Science and Engineering, Babes-Bolyai University, Fantanele 30, 400294 Cluj-Napoca, Romaniae Faculty of Humanities, Valahia University, Lt. Stancu Ion 34-36, 130115 Targovițte, Romaniaf Institute of Speology, Romanian Academy, 400006 Cluj-Napoca, Romania

a r t i c l e i n f o

Article history:Received 24 October 2014Received in revised form12 December 2014Accepted 15 December 2014Available online xxx

Keywords:OSL datingRadiocarbon datingQuartz grain sizeRomania

* Corresponding author. Faculty of EnvironmentaBabes-Bolyai University, Fantanele 30, 400294 Cluj-N

E-mail address: alida.timar@ubbcluj.ro (A. Timar-G

http://dx.doi.org/10.1016/j.quageo.2014.12.0051871-1014/© 2014 Elsevier B.V. All rights reserved.

Please cite this article in press as: Trandafir,(Northeastern Romania), Quaternary Geoch

a b s t r a c t

Previous works focused on optically stimulated luminescence dating of quartz extracted from Romanianand Serbian loess reported significant discrepancies between ages obtained on fine (4e11 mm) and coarse(63e90 mm) quartz. The present study is directed at expanding these investigations. The SAR-OSL anddouble SAR-OSL protocols are applied on quartz of different grain sizes belonging to 9 samples extractedfrom a newly identified archaeological site at Bistricioara-Lut�arie III on the Bistrița Valley (NE Romania).Radiocarbon ages are also obtained for the 3 uppermost cultural layers hosted in the loess-like deposit.

Discrepant ages are obtained between fine (4e11 mm) and coarse (63e90 and 90e200 mm, respec-tively) quartz for equivalent doses higher than ~80e100 Gy. However, a very good agreement is achievedfor the youngest sample, with an age of ~8 ka (with a De of 38 Gy for fine and 35 Gy for coarse grains,respectively). The comparison with independent control provided by radiocarbon dating suggests betteragreement of ages calculated for coarse quartz. Our results are once again proof that concerns should beraised regarding the reliability of the equivalent doses obtained on quartz samples for which the labo-ratory dose response cannot be fitted by a single saturating exponential function. Further systematicinvestigations are required regarding the very different saturation characteristics of fine and coarsegrained quartz.

© 2014 Elsevier B.V. All rights reserved.

1. Introduction

The Moldavian sector of the Bistrița valley (Carpathian Moun-tains) hosts the highest density of Palaeolithic settlements yetidentified in Romania: 25 find spots, some excavated on largesurfaces from the 1950's onwards (see review in Anghelinu et al.,2012). Most settlements however have been identified in rathercondensed loess and colluvium sequences on the middle riverterraces, and largely assigned to the Gravettian and EpigravettianUpper Palaeolithic technocomplexes. Notwithstanding their un-usual density, very few of these archaeologically rich, pluristratified

l Science and Engineering,apoca, Romania.abor).

O., et al., OSL dating of fine aronology (2014), http://dx.do

settlements own a reliable numerical chronology and an accuratepalaeoenvironmental contextualization. Despite continuousresearch efforts, the available chronological record still relies on asmall number of classic radiocarbon dates, supplemented by anequally limited and unequally distributed number of AMS radio-carbon ages, and isolated palaeomagnetic and luminescence in-vestigations (Steguweit et al., 2009; Zeeden et al., 2009; Anghelinuet al., 2012). Consequently, many aspects of the regional Palae-olithic cultural dynamics, from the cycles of human presence in thearea to the detailed understanding of site formation, processes orenvironmental contexts of human occupations, are still unclear.Establishing a reliable chronological framework by concomitantlyapplying several dating methods appears like a first logical step insolving some of these lingering issues.

Apart from direct dating of organic remains using the radio-carbon method, one of the methods of choice for directly dating

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sediment particles/deposits is optically stimulated luminescence(OSL). Once the single aliquot measurement protocol has beenestablished (Murray and Wintle, 2000, 2003), quartz was generallyaccepted as a universal dosimeter. However, a series of recent in-vestigations carried out on quartz of different grain sizes extractedfrom Romanian (Timar-Gabor et al., 2011, 2012; Timar-Gabor andWintle, 2013; Constantin et al., 2014a) and Serbian (Timar-Gaboret al., in press) loess yielded intriguing results. The optical agesobtained on coarse quartz (63e90 mm) were reported to be sys-tematically higher than those on fine quartz (4e11 mm); the causeof this chronological discrepancy being hitherto not fully explained.Both grain fractions behaved well in the SAR protocol, passing allprocedural tests, and factors such as partial bleaching, internalradioactivity or other microdosimetric effects have already beenruled out (Timar-Gabor et al., 2011). It is important to note that forequivalent doses higher than ~100 Gy, for all previously investi-gated samples the equivalent doses obtained on coarse quartz weresystematically higher than for the finer material, which is not to beexpected based on natural dose rate considerations. It is alsoessential to note that for younger ages (with equivalent doses lyingin the almost linear part of the dose response curves) agreementhas been found between the fine and coarse quartz ages(Constantin et al., 2014b; Timar-Gabor et al., in press). In addition, itshould be pointed out that the laboratory dose response could bewell fitted only by a sum of two single saturating exponentialfunctions, and different saturation characteristics between the fineand coarse fractions were noted (see Timar-Gabor et al., 2012;Constantin et al., 2012). At the moment, the source of the agediscrepancy is thought to reside, at least partly, in the differentsaturation characteristics of fine grains compared to the coarsegrains, and in the differences reported between the laboratory andthe natural dose response curves (Timar-Gabor and Wintle, 2013).

Thus, in order to get more insights into the reason for discrepantfine and coarse quartz ages further investigations are needed,preferably on various sedimentary settings, including archaeolog-ical profiles. SAR-OSL dating has many inbuilt rigour checks fortesting the reliability of measuring laboratory given doses, such asrecycling, recuperation, IR depletion ratio tests, thermal stabilitytests or dose recovery tests. However, these tests do not guaranteethe accurate measurement of the natural dose. As such, it is desir-able to have independent age control. Along with tephrochronol-ogy, (e.g. Constantin et al., 2012), radiocarbon dating is a suitablemethod. Here we focus on the luminescence dating results ob-tained on the recently identified archaeological settlement at Bis-tricioara-Lut�arie III (Ceahl�au Basin), which apart from contributingto a better understanding of the chronology of Upper Pleistocenedeposits in Northeastern Romania, also raise interesting method-ological challenges. To increase the confidence of the results,luminescent investigations have been independently carried out intwo laboratories in Romania (Cluj-Napoca) and Germany (Bayr-euth). Besides obtaining a chronological framework for the site, thestudy aimed at (i) extending our previous area of investigation inorder to see whether the differences between fine and coarsequartz ages are a more general feature, or are restricted to typicalloess sections in South East Europe and (ii) discussing the lumi-nescence ages obtained on different grain size fractions in a moregeneral chronological frame, obtained by applying radiocarbondating on the archaeological layers.

2. Study site

The archaeological site at Bistricioara-Lut�arie III (BL III) is locatednearby the better known Bistricioara Lut�arie I and II settlements, onthe 16e18 m high terrace of the river (around 500 m in altitude),covered with loess derivates accumulated on a gentle slope. Loam

Please cite this article in press as: Trandafir, O., et al., OSL dating of fine a(Northeastern Romania), Quaternary Geochronology (2014), http://dx.do

exploitation partially destroyed the settlement, which currentlystands in a ca. 3.5 m high open profile facing northeast. A small-scale excavation of the exposed area took place in 2008(Anghelinu et al., 2012). Whereas only one consistent archaeolog-ical Epigravettian layer has been identified in 2008, subsequentdestruction by local-scale quarrying revealed at least 5 otherpotentially older Paleolithic cultural layers, in the form of firetraces, charcoal accumulations and/or scattered lithics (Fig. 1).

3. Radiocarbon dating

The radiocarbon ages of BL III profile were obtained by accel-erator mass spectrometry (AMS) 14C dating using facilities at Her-telendi AMS Lab (Debrecen, Hungary) and Erlangen (sample Erl-12851v previously published in Steguweit et al., 2009). All mea-surements were performed on wood charcoal (Table S1) handpicked under the microscope and treated using the standard acid-base-acid (ABA) method, i.e. in a sequence of 1N HCl, distilledwater, 1M NaOH, distilled water, and then 1N HCl (Moln�ar et al.,2013a,b). After the final acid wash, samples were re-washed withdistilled water to neutral pH (4e5) and freeze-dried. CO2 wasextracted by combustion of the ABA pre-treated samples andfurther purified cryogenically and then graphitized. 14C measure-ments were done on the graphitized samples using a compactradiocarbon AMS system (EnvironMICADAS) (Moln�ar et al., 2013b).Conventional radiocarbon ages were converted to calendar agesusing the CALIB REV7.0.1 program and the IntCal13 calibrationcurve of Reimer et al., 2013 and discussed as calendar ages (BP) at 2-sigma confidence level (95.4%).

4. Optical dating

4.1. Samples and analytical facilities

Two sets of luminescence samples were collected at the Bis-tricioara-Lut�arie III study site. The first set, encompassing 5 samplesextracted in 6 cm-diameter and 20 cm-long stainless steel cylinderswas processed at the Luminescence Dating Laboratory of Babeș-Bolyai University. After the removal of the material at each end ofthe cylinders (used for dose rate and water content de-terminations), the remaining core material was processed underlow intensity red-light conditions to extract fine (4e11 mm) andcoarse (63e90 mm) quartz as per previously published protocols(e.g., Constantin et al., 2012). In addition, the density separationtechnique using sodium polytungstate was repeated two-threetimes for most samples, since preliminary measurements basedon IR depletion tests showed a significant feldspathic component(Duller, 2003). Luminescencemeasurements were performed usingan automated Risø TL/OSL-DA-20 reader equipped with blue andinfrared light diodes emitting at 470 ± 30 nm and 875 ± 80 nm,respectively. The emitted luminescence signals were detected by anEMI 9235QA photomultiplier tube through a 7.5 mm thick Hoya U-340 UV filter. Irradiations were carried out using the incorporated90Sre90Y radioactive source calibrated against gamma dosed cali-bration quartz supplied by Risø National Laboratory. A dose rate of0.148 Gy/s for the coarse quartz grains mounted on stainless steeldiscs was obtained, while for the fine grains on aluminium discs thedose rate was 0.120 Gy/s.

The second set, represented by a sediment block (called ‘TheCube’ throughout this paper), was processed at the LuminescenceLaboratory at Bayreuth University. Further on, 4 samples with asediment thickness of ~2e3 cm were extracted in subdued red-light conditions from The Cube after removing the outer layerexposed to daylight. The same conventional preparation protocolwas used for extraction of quartz of 3 different grain sizes: 4e11 mm,

nd coarse quartz from a Palaeolithic sequence on the Bistrița Valleyi.org/10.1016/j.quageo.2014.12.005

Fig. 1. A. Map of Europe with the Romanian teritory highlighted. B. Loess distribution in Romania. The studied site (Bistricioara-Lutarie III) is shown as a filled star. C. The studiedsedimentary profile.

O. Trandafir et al. / Quaternary Geochronology xxx (2014) 1e6 3

63e90 mm and 90e200 mm, with an additional HF etching (HF 40%for 40 min) for coarse grains due to persisting feldspar contami-nation. The measurement equipment was a Risø TL/OSL-DA-15reader and the obtained dose rate for fine grains pipetted ontoaluminium discs was 0.138 Gy/s and for coarse grains attached tothe central 3 mm of aluminium cups 0.127 Gy/s.

4.2. Luminescence characteristics

4.2.1. General behaviour in the SAR and double-SAR protocolThe equivalent doses (De) of the fine and coarse quartz grains

analysed at Cluj-Napoca laboratory were measured using thesingle-aliquot regenerative dose (SAR) protocol (Murray andWintle, 2000, 2003). The net continuous wave OSL (CW-OSL)signal of the aliquots was evaluated from the first 0.308 s of thedecay curve with an early background subtraction (Ballarini et al.,2007). A preheat temperature of 220 �C for 10 s and a cutheat to180 �C were employed throughout the measurement protocol,

Fig. 2. Dose recovery test results for fine quartz extracted from all samples and forcoarse quartz from sample BL3 1.6. A preheat of 220 �C for 10 s was used. The lines aremeant as guidelines, with the dotted lines integrating a 10% deviation from unity. nrepresents the number of aliquots used. The inset shows the equivalent dose depen-dence on preheat temperatures for 4e11 mm fraction from sample BL3 1.2.

Please cite this article in press as: Trandafir, O., et al., OSL dating of fine a(Northeastern Romania), Quaternary Geochronology (2014), http://dx.do

based on preheat plateau experiment results (see inset in Fig. 2)and on previous investigations on Romanian loess (Timar-Gaboret al., 2011, 2012; Vasiliniuc et al., 2011). The OSL response to afixed test dose of 17 Gy was used to correct for sensitivity changes.At the end of each SAR cycle, a high-temperature bleach was per-formed by blue LED stimulation for 40 s at 280 �C (Murray andWintle, 2003). Typical SAR growth curves and OSL decay curves,as insets, for samples BL3 1.2 (4e11 mm) and BL3 1.6 (63e90 mm) areshown in Fig. S1. The OSL signals for all samples (both grain sizes)displayed a rapid decay during optical stimulation, with indistin-guishable natural and regenerated signals. Recycling, IR depletionand recuperation tests have been employed to check for the suit-ability of these samples for De determination using the SAR pro-tocol. Aliquots were accepted if recycling and IR depletion ratioswerewithin 10% deviation from unity and values less than 2% of thenatural signal could be recuperated. Dose recovery tests (Murrayand Wintle, 2003) were employed for fine-grained quartz fromall samples and for coarse-grained quartz from the youngest sam-ple. As depicted in Fig. 2, relatively good recovered/given ratios

Fig. 3. Comparison between sensitivity corrected growth curves constructed up to1 kGy on fine quartz using the SAR protocol (circles) and the double SAR protocol(squares) (IR stimulation for 100 s at 125 �C prior to OSL), respectively, for sample BL31.1. All growth curves are well represented by a double saturating exponentialregression model.

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were obtained in all cases.As mentioned in Section 4.1, the coarse grain fractions initially

displayed a significant feldspathic contribution and required threeconsecutive heavy liquid separations. To ensure that any possiblecontribution from signals derived from feldspars has beenremoved, a double-SAR protocol (Roberts and Wintle, 2001;Banerjee et al., 2001) was also employed for both grain sizes,meaning that IR stimulation was performed for 100 s at 125 �C (IRbleach) prior to the blue LED OSL stimulations, and the [post-IR]OSL signal was used for De calculation. All values for equivalentdoses obtained using both protocols are presented in Table S2. Agood reproducibility was observed between SAR and double-SARequivalent doses estimated for the same grain size of each sam-ple, the values being the same within 95% confidence limits.Moreover, we compared SAR and double-SAR performances interms of signal growth up to 1 kGy (see Fig. 3) and no significantdifferences could be observed between the two patterns. Since it iswell known that feldspars present different saturation character-istics than quartz, we can be confident, when observing Fig. 3 andthe saturation characteristics presented in Table S3, that thedouble-SAR protocol was successful in isolating the quartz-dominated signal. As such, equivalent doses estimated both withSAR and with double-SAR protocols (where applicable) wereconsidered when calculating the OSL ages.

In regard to the samples extracted from The Cube, only thedouble-SAR protocol was used, with a thermal treatment consistingof a preheat temperature of 200 �C for 10 s and a cutheat to 160 �C,as suggested by dose recovery tests carried out as a function ofpreheat temperature (see Fig. S2). The acceptance criteria for ali-quots are similar to those mentioned above, with recuperationvalues less than 5% of the natural signal considered adequate. Thenet luminescence signal was integrated from the first 0.6 s of op-tical stimulation minus a late background calculated from 32.5 to40 s. The main rejection reason for individual aliquots was poorrecycling in most cases, especially for fine grains of BT1286. Fromthis sample, the 63e90 mm fraction was found to be in saturation,which suggests that the material of the find layer exhibits differentluminescence properties than surrounding sediments.

4.2.2. Dose response for high dosesDose response for high doses was investigated for each grain

size of the oldest (BL3 1.1 and BL3 1.2) and youngest (BL3 1.6)sample, respectively. The sensitivity corrected growth curvesextending up to 2 kGy are best fitted by a sum of two saturating

Fig. 4. Comparison between averaged sensitivity-corrected dose responses constructed for fidata point represents the average value of at least 5 replicate measurements. The data arestars.

Please cite this article in press as: Trandafir, O., et al., OSL dating of fine a(Northeastern Romania), Quaternary Geochronology (2014), http://dx.do

exponential functions. More details on the fitting parameters forindividual aliquots can be found in Table S3. It is interesting to notethat for the lowermost sample (BL3 1.1), although the fine quartznatural OSL was found significantly below the saturation level, thecounterpart signals of coarse quartz grains have been found in andabove laboratory saturation level (see Fig. 4a). As such, the equiv-alent doses estimated based on these growth curves are not rele-vant and cannot yield reliable ages. Similarly, the signals of some ofthe coarse quartz aliquots from sample BL3 1.2 are in saturation andwere removed from the De calculation. Fundamentally differentgrowth patterns were observed between the fine (4e11 mm) andcoarse (63e90 mm) quartz for all samples analysed, similar to thefindings reported on quartz extracted from loess (Timar-Gaboret al., 2011, 2012; in press). Significant differences can also beobserved between D02 values of the same grain fraction(63e90 mm) from distinct samples: BL3 1.6 presents higher satu-ration characteristics (see values in Table S3) than the older sam-ples (BL3 1.1 and BL3 1.2). This can be attributed to possibledifferent origins of the grains. However, for all 3 samples there is aclear similar trend between saturation parameters of fine andcoarse quartz, with the latter reaching saturation much earlier(Fig. 4).

4.2.3. Equivalent dosesAt least 11 aliquots were used for each grain size of each sample

in order to calculate the De, with the exception of the 63e90 mmfraction from sample BT1287, where only 7 replicatemeasurementswere accepted. The average De values (±1 standard error) aresummarised in Table S2 (samples analysed in Cluj) and Table S5(samples extracted from The Cube), along with the correspondingrecycling, IR depletion (where applicable) and recuperation data.Apart from the youngest sample (BL3 1.6), the other 5 samplesmeasured in Cluj presented systematically higher De values forcoarse (63e90 mm) quartz than for fine quartz. This is counter-intuitive when considering the alpha-particle contribution to theannual dose rates of finer grains, which should result in higher De

values for this material. However, these results are in agreementwith previously reported similar observations (Timar-Gabor, 2011;Timar-Gabor and Wintle, 2013; Constantin et al., 2014a). Whenconsidering sample BL3 1.6, the results are as expected, with a De of38 ± 0.4 Gy for the fine fraction and 35 ± 1 Gy for coarse quartz.

The 4 samples extracted from The Cube show a similar behav-iour. However, despite the fact that the 63e90 mm ages areconsistently higher than the 4e11 mm ages, there is no systematic

ne and coarse quartz extracted from sample (a) BL3 1.1 and (b) BL3 1.6. In all cases, eachbest fitted with a double saturating exponential function. Natural signals are shown as

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trend observable for the 90e200 mm fraction.

4.3. Dose rate determination

Radionuclide (U-238/Ra-226, Th-232, K-40) specific activities(Table S4) were measured using high-resolution gamma-ray spec-trometry and the dose rates were derived using the conversionfactors of Adamiec and Aitken (1998). In the case of the samplesextracted from The Cube, sediment from the same layer as thesamples was analysed by alpha-counting for determination of Uand Th concentrations and by ICP-OES for K concentration(Table S5). To correct for the effect of moisture, the measured watercontent of the samples when collected was used for age calcula-tions, with a relative error of 25%. Because the water content of thecultural layer within The Cube (sample BT1286) differed consider-ably from the surrounding loess-like sediment, further adjustmentsserved to approximate the effective radiation attenuation by porewater experienced by The Cube samples, taking into account thethickness of individual layers (Table S5).

4.4. Optical ages

The optical ages are reported in Table S4 (BL3 samples) andTable S5 (The Cube) and are plotted against sample depth andcompared with calibrated radiocarbon ages for a better visual-isation (Fig. 5). As expected from the De results discussed in Section4.2.3, although each grain size fraction yielded a set of agesconsistent with the stratigraphic position of the samples, signifi-cant discrepancies were obtained between grain fractions. Opticalages ranging from 8.0± 1.1 ka to 76.3± 8.4 kawere obtained for fine(4e11 mm) grains, whereas for the coarse (63e90 mm) quartz datesbetween 8.6 ± 1.1 ka and 50.7 ± 6.7 ka were found.

5. Discussion and conclusions

5.1. Methodological

Discrepant ages were obtained between fine (4e11 mm) andcoarse (63e90 and 90e200 mm, respectively) quartz for equivalent

Fig. 5. Optical ages of fine and coarse quartz grains from all samples studied comparedwith radiocarbon ages for the topmost three cultural layers. Ages for the 63e90 mmfractions of BL3 1.1 and BT1286 could not be obtained, since the samples were in dosesaturation. The fine fraction of BT1287 was affected by heavy feldspar contamination.The errors quoted for luminescence ages represent 1s and for the calibrated radio-carbon ages (yr BP) 2s, respectively.

Please cite this article in press as: Trandafir, O., et al., OSL dating of fine a(Northeastern Romania), Quaternary Geochronology (2014), http://dx.do

doses higher than ~80e100 Gy (Table S4, S5). However, a very goodagreement was achieved for the youngest sample, with an age of ~8ka (with a De of 38 Gy for fine and 35 Gy for coarse grains,respectively). For this particular sample the natural signal wasinterpolated on the laboratory dose response curve in a regionwhere both exponential components are well below saturation,contrary to the case of the rest of the samples. These results suggestthat the differences obtained may be generated by a dose depen-dent phenomenon.

The age discrepancy reported on fine and coarse quartz in thisstudy proofs yet again that concerns should be raised regarding thereliability of the equivalent doses obtained on quartz samples forwhich the laboratory dose response cannot be fitted by a singlesaturating exponential function. In addition, the samples investi-gated in this study do not belong to a typical loess section, as thepreviously analysed quartz from Romania (Timar-Gabor et al., 2011,2012) and Serbia (Timar-Gabor et al., in press), suggesting that thedifferent behaviour of fine and coarse quartz is not limited to suchsamples, or to quartz of a certain origin.

Comparison of optical ages with independent control providedby 14C dating shows better agreement for the coarse grain ages,both for The Cube samples and those below (BL3 1.3 and BL3 1.4).This study further demonstrates that the discrepancy between fineand coarse quartz ages is independent from laboratory-specificprocedures of sample preparation, luminescence and analyticalmeasurements. Finally, the very different dose response charac-teristics of coarse and fine grained quartz to high laboratory betadose rates ask for further systematic investigations and questionthe general equivalence of luminescence production in nature andin the laboratory for silt-sized quartz.

5.2. Chronological

The newly obtained results have some key chrono-cultural im-plications. The OSL ages on coarse quartz show a good agreementwith the calibrated radiocarbon dates. They point to the existenceof some older, likely Gravettian occupation layers, as alreadyidentified in the neighbouring settlements at Bistricioara I-II(Steguweit et al., 2009), but also andmore importantly to a possiblyearlier presence of the Upper Palaeolithic in the area. The chrono-logical breadth and improved resolution of the geological archivemakes Bistricioara-Lut�arie III a strategic settlement for under-standing the regional Upper Pleistocene palaeoenvironmental andcultural dynamics, highlighting the need for future investigations.

Acknowledgements

O.T. aknowledges financial support from the Sectoral Opera-tional Programme for Human Resources Development 2007-2013,co-financed by the European Social Fund, under the project POS-DRU/159/1.5/S/132400 - “Young successful researchers e profes-sional development in an international and interdisciplinaryenvironment”. D.V. acknowledges support from grant GTC-34029/2013 from Babes-Bolyai University and project PN-II-ID-PCE-2012-4-0530 ‘Millennial-scale geochemical records of anthropo-genic impact and natural climate change in the Romanian Carpa-thians’. C.S. acknowledges the Deutsche Forschungsgemeinschaft(DFG), which funded the project SCHM3051/1-1.

Appendix A. Supplementary data

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.quageo.2014.12.005.

nd coarse quartz from a Palaeolithic sequence on the Bistrița Valleyi.org/10.1016/j.quageo.2014.12.005

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