Marine Geology 255 (2008) 149–155

Contents lists available at ScienceDirect

Marine Geology

j ourna l homepage: www.e lsev ie r.com/ locate /margeo

Detrital fine-grained sediment contribution from Taiwan to the northern South ChinaSea and its relation to regional ocean circulation

Zhifei Liu a,⁎, Shouting Tuo a, Christophe Colin b, James T. Liu c, Chi-Yue Huang d, Kandasamy Selvaraj c,Chen-Tung Arthur Chen c, Yulong Zhao a, Fernando P. Siringan e, Sébastien Boulay a, Zhong Chen f

a State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, Chinab Laboratoire IDES, Bât. 504, UMR 8148 CNRS, Université de Paris XI, Orsay 91405, Francec Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwand Department of Earth Sciences, National Cheng Kung University, Tainan 70101, Taiwane Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippinesf South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China

⁎ Corresponding author. Tel.: +86 21 6598 4877; fax:E-mail address: lzhifei@mail.tongji.edu.cn (Z. Liu).

0025-3227/$ – see front matter © 2008 Elsevier B.V. Aldoi:10.1016/j.margeo.2008.08.003

a b s t r a c t

a r t i c l e i n f o

Article history:

Results of clay mineralogy i Received 6 November 2007Received in revised form 3 July 2008Accepted 5 August 2008

Keywords:clay mineralssurface sedimentsprovenanceSouth China SeaTaiwan

n 140 samples collected in major rivers and lakes in southwestern Taiwan and onthe seafloor off Taiwan in the northeastern South China Sea (SCS), combined with clay mineral records of thePearl River drainage basin, rivers in Luzon, and the South China shelf and slope, are used to semi-quantitatively evaluate the detrital fine-grained sediment contribution of Taiwan to the northern SCS. Theclay mineral assemblage of the Taiwan-sourced sediments consists dominantly of illite (average 56%) andchlorite (41%), with very scarce kaolinite and smectite. Their respective distribution from the rivers and lakesto the seafloor off Taiwan does not show obvious basin-wide differences. Linear correlations of illitechemistry index with illite crystallinity and of illite crystallinity with kaolinite (%) present two end-membersof provenances, the Pearl River and Taiwan, for the South China shelf and slope. Assuming that kaolinite inthe northern SCS is provided completely from the Pearl River, the contribution of Taiwan in clay minerals isevaluated as 29% to the South China shelf and 23% to the South China slope, respectively. Accordingly, thecontribution of the Pearl River to the South China shelf and slope is 52% and 31%, respectively. The Luzon Arcaccounts for the rest of clay mineral components for the northern SCS mainly by providing smectite. TheBashi Strait-crossed branches of the southward deep North Pacific Deep Water and the northward surfaceKuroshio Current in the western Pacific may transport Taiwan-sourced suspended sediments westwards tothe northern SCS.

© 2008 Elsevier B.V. All rights reserved.

1. Introduction

Determining the provenance of detrital sediments in the ocean isprerequisite for understanding environmental and climatic conditionsthat occurred in land-source areas. Sources of terrigenous matters inmarginal seas with bounded lands are particularly complicatedbecause they may involve diverse geological settings. One of suchcases is the South China Sea (SCS), the largest marginal sea in thewestern Pacific, surrounded by the Asian continent and Taiwan to thenorth and west and Philippine islands and Borneo to the east andsouth (Fig. 1A). Numerous rivers including both world largest rivers(e.g., Mekong River, Pearl River, and Red River) and small mountainousrivers (e.g., rivers in southwestern Taiwan) supply as much as 570 Mt/yr of suspended (fine-grained) sediments to the SCS (Table 1), repre-senting 2.8% of estimated global suspended sediment discharge to the

+86 21 6598 8808.

l rights reserved.

world oceans (Milliman and Syvitski, 1992). The river-borne terrige-nous sediments compose ∼80% of total SCS surface sediments (Huang,2004) and have formed high sedimentation-rate deposition in thegeological past (Wang et al., 2000), especially for sediment drifts onthe northern slope, where the Holocene sedimentation rate can reachas high as 70 cm/kyr (Bühring et al., 2004). The terrigenous detritalsedimentary archives in the SCS, therefore, have become ideal to studythe high-resolution history of the East Asian monsoon evolution(e.g., Wang et al., 1999; Wehausen and Brumsack, 2002; Clift et al.,2002; Liu et al., 2003, 2005; Wang et al., 2005; Boulay et al., 2005;Wan et al., 2007).

The northern SCS has offered a special attraction for marinegeologists because of the very high sedimentation rate of its detritalsediments (e.g., Wang et al., 2000). However, its sedimentary source isnot well established because the geology of two major potentialsource areas, South China and southwest Taiwan, is similar with samecratonic Mesozoic–Cenozoic sedimentary rocks (Commission for theGeological Map of the World, 1975) and Nd isotopic values (Li et al.,2003; Boulay et al., 2005). Most of previous studies mainly at Ocean

150 Z. Liu et al. / Marine Geology 255 (2008) 149–155

Table 1Drainage area, runoff, and suspended sediment discharge of major rivers flowingdirectly into the South China Sea (SCS)

River Drainagearea

Runoff Suspendedsedimentdischarge

Data source

(km2) (m/yr) (Mt/yr)

Ta-An (Taiwan) 633 1.6 7.1 Dadson et al. (2003)Wu (Taiwan) 1981 1.9 9.8Cho-Shui (Taiwan) 2989 1.2 54.1Pei-Kang (Taiwan) 597 1.3 2.2Pa-Chang (Taiwan) 441 1.5 6.3Tseng-Wen (Taiwan) 1157 1.1 25.1Erh-Jen (Taiwan) 175 1.8 30.2Kao-Ping (Taiwan) 3067 2.5 49.0Tung-Kang (Taiwan) 175 2.9 0.4Lin-Pien (Taiwan) 310 2.5 3.3Total SW Taiwan 187.5Pearl (South China) 440,000 6.9 69.0 Milliman and

Syvitski (1992)Red (Vietnam) 120,000 10.0 130.0Mekong (Vietnam) 790,000 5.9 160.0Chao Phraya (Thailand) 160,000 1.9 11.0Baram (Malaysia) 22,800 2.5 12 Hiscott (2001),

Lambiase et al. (2002)

151Z. Liu et al. / Marine Geology 255 (2008) 149–155

Drilling Program (ODP) Leg 184 sites (partly shown in Fig. 1A) on thenorthern slope of the SCS considered the Pearl River as the mainsedimentary source (Wehausen and Brumsack, 2002; Clift et al., 2002;Tamburini et al., 2003; Li et al., 2003; Boulay et al., 2003) with anadditional volcanic source (Boulay et al., 2005). But Taiwan presentsone of the highest erosion rates in the world and exports 384 Mt/yr ofsuspended sediments to the ocean, with about half of the totalsediments directly to the SCS (Dadson et al., 2003). Such a fine-grainedsediment discharge is even larger than any other provenance sur-rounding the SCS including the Pearl, Red, andMekong rivers (Table 1)andmust have played a significant role in sediment components in theSCS, especially on the northern slope.

One way to distinguish the fine-grained sediments of South Chinafrom Taiwan is to use clay mineralogy of the sediments because clayminerals in river and marine sediments reflect the intensity ofchemical weathering of their source areas (Chamley, 1989). In SouthChina, themore or less flat hinterland of the Pearl River drainage basinhas undergone deep and long-term lateritic weathering during Neo-gene. The river sediments with kaolinite and Al-rich illite dominanceindicate a strong chemical weathering (Liu et al., 2007a,b). In Taiwan,steep erosional gradients, short transport distances, and short storagetimes have significantly increased the intensity of physical weath-ering. The sediments present only amoderate chemical weathering onthe basis of major and trace element geochemistry (Selvaraj and Chen,2006). A few samples from Taiwan also suggest that the clay mineralassemblage consists mainly of primary minerals of illite and chlorite(Jiang et al., 2006; Wan et al., 2007), indicating a strong physicalweathering. Therefore, the clay mineralogy of sediments in the twoareas needs to be completely contrasted. But there is no detailed claymineralogical data available from Taiwan. In this study, we firstlyestablish the clay mineralogy of Taiwan by investigating sedimentsin major rivers and lakes in southwestern Taiwan and on the seaflooroff Taiwan in the northeastern SCS. Then we combined these datawith clay mineral records of the Pearl River drainage basin, rivers inLuzon, and the South China shelf and slope to semi-quantitatively

Fig. 1. (A) Bathymetry of the South China Sea (SCS) and major rivers on adjacent continents2007a,b), in the Luzon rivers, and on the South China shelf and slope (Liu et al., 2003; Boulayshown. In Luzon: 1, the Cagayan River; 2, the Pampanga River; 3, the Agno River. (B) Locationaccretionary prism east of the Manila trench, and passive continental margin west of the Mdetailed GPS positions; the Manila trench after Huang et al. (2006). (C) Enlarged sample loc

evaluate the detrital fine-grained sediment contribution of Taiwan tothe northern SCS.

2. Materials and methods

A set of 140 samples from southwestern Taiwan and off Taiwan inthe northeastern SCS (19 from rivers, 5 from lakes, and 116 from theseafloor) are examined for clay mineralogy (Fig. 1B, C; Supplementarydata Table S1). River and lake samples, covering with all majormountainous rivers and lakes in southwestern Taiwan, were collectedfrom surface muddy channel/bed deposits to avoid contaminationfrom bank sediments. The seafloor samples with different tectonicsettings, including 11 from the SW Taiwan shelf (tectonically stable),87 from the accretionary prism east of the Manila trench (tectonicallyactive), and 18 from the passive continental marginwest of theManilatrench (tectonically stable), were selected from surface sediments ortop parts of box and piston cores, taken by the R/V Ocean Researcher I& III during 2003–2006. In order to compare with clay mineral com-positions derived from Taiwan, 7 samples from three largest rivers inLuzon, northern Philippines (3 from the Cagayan River, 2 from thePampanga River, and 2 from the Agno River) were collected during thesummer season of 2007 (Fig. 1A, Supplementary data Table S1). Allsamples were analyzed for clay minerals.

Clay minerals were identified by X-ray diffraction (XRD) using aPANalytical diffractometer at the Laboratoire IDES, Université de ParisXI on oriented mounts of non-calcareous clay-sized (b2 μm) particles(Holtzapffel, 1985). The oriented mounts were obtained following themethods described in detail by Liu et al. (2004). Three XRD runs wereperformed, following air-drying, ethylene-glycol solvation for 24 h,and heating at 490 °C for 2 h. Identification of clay minerals was mademainly according to the position of the (001) series of basal reflectionson the three XRD diagrams. Semi-quantitative estimates of peak areasof the basal reflections for the main clay mineral groups of smectite(including mixed-layers) (15–17 Å), illite (10 Å), and kaolinite/chlorite(7 Å)were carried out on the glycolated curve (Holtzapffel,1985) usingthe MacDiff software (Petschick, 2000). Relative proportions ofkaolinite and chlorite were determined based on the ratio from the3.57/3.54 Å peak areas. Following the laboratory routine at bothLaboratoire IDES of Université de Paris XI and Laboratoire PBDS ofUniversité de Lille I (Liu et al., 2003, 2007b), the weighting factorsintroduced by Biscaye (1965) are not used when generating relativeweight percentages of each clay mineral. Replicate analyses of a fewselected samples gave a precision of ±2% (2σ). Based upon the XRDmethod, the semi-quantitative evaluation of each clay mineral hasan accuracy of ∼5%. Additionally, some mineralogical characters ofillite were determined on the glycolated curve. Illite chemistry indexrefers to a ratio of the 5 Å and 10 Å peak areas. Ratios below 0.5represent Fe–Mg-rich illite (biotite, mica), which are characteristicof physical erosion; ratios above 0.5 are found in Al-rich illite(muscovite), which are released following strong hydrolysis (Esque-vin, 1969; Gingele et al., 1998). Illite crystallinity was obtained fromhalf height width of the 10 Å peak. Lower values represent the highercrystallinity, characteristic of weak hydrolysis in continental sourcesand arid and cold climate conditions (Chamley, 1989; Krumm andBuggisch, 1991; Ehrmann, 1998).

In order to determine the provenance of detrital fine-grained sedi-ments in the northern SCS, literature data of clay minerals in 38 sur-face samples from the Pearl River drainage basin (Liu et al., 2007a,b),16 surface samples from the South China shelf (Boulay et al., 2004),and 9 surface samples from the South China slope (Boulay et al., 2004)

and islands. Locations of surface sediments in the Pearl River drainage basin (Liu et al.,et al., 2004, 2005) are displayed; positions of ODP Leg 184 Sites 1145 and 1146 are alsos of surface sediments from rivers and lakes in southwestern Taiwan and from the shelf,anila trench off Taiwan in the northeastern SCS. See Supplementary data Table S1 forations off the Kao-Ping River estuary.

Fig. 2. Distribution of average clay mineral assemblages in lakes and rivers insouthwestern Taiwan and on the shelf, accretionary prism east of the Manila trench,and passive continental margin west of the Manila trench off Taiwan. See Fig. 1 for theirgeographic locations and Supplementary data Table S1 for detailed GPS positions andclay mineral proportions. N, number of surface samples.

152 Z. Liu et al. / Marine Geology 255 (2008) 149–155

including core top samples of ODP Site 1145 (Boulay et al., 2005) andSite 1146 (Liu et al., 2003) (Fig. 1A) were referred for clay componentcomparison of sources. All the referred literature data were generatedusing exactly the same analytical and calculational methods with thisstudy by a same research group (Liu et al., 2003; Boulay et al., 2004,2005; Liu et al., 2007a,b) to keep the consistency of data comparison.

3. Results

The clay mineral assemblages in rivers and lakes of southwesternTaiwan are similar, predominantly consisting of illite (44–66%) andchlorite (33–48%), with very scarce kaolinite (0–4%) and smectite(0–8%) (Supplementary data Table S1). Their average percentage is55% for illite, 43% for chlorite, 1% for kaolinite, and 1% for smectite,respectively (Table 2, Fig. 2). Clayminerals on the southwesternTaiwanshelf contain only illite (57–61%, average 59%) and chlorite (39–43%,average 41%), without measurable kaolinite and smectite (Fig. 2). Theaccretionary prism east of the Manila trench is characteristic ofdominating illite (49–64%, average 56%) and chlorite (35–42%, average39%), with scarce kaolinite (0–5%, average 2%) and smectite (0–15%,average 3%) (Fig. 2). The passive continental marginwest of theManilatrench has a similar clay mineral distribution with the accretionaryprism, with slight increase in smectite (2%) and decrease in illite (2%),respectively (Table 2, Fig. 2). To sum up, the results of all samples fromthe rivers and lakes in southwestern Taiwan to the shelf, accretionaryprism and passive continental margin on the seafloor off Taiwanpresent dominating illite (average 56%) and chlorite (41%), with veryscarce kaolinite and smectite (Fig. 2). In addition, the illite chemistryindex (0.26–0.40) and illite crystallinity (0.12–0.22°Δ2θ) also indicateconcentrative values at 0.36 and 0.16°Δ2θ, respectively (Supplemen-tary data Table S1, Table 2).

For three Luzon rivers, all samples present predominant smectite(83–92%, average 88%), with minor kaolinite (average 9%) and scarcechlorite and illite (Supplementary data Table S1). There is no obviousdifference in clay mineral distribution among various river drainagebasins in Luzon, suggesting the major contribution of smectite fromLuzon to the SCS.

4. Discussion

The similar clay mineral distribution from southwest Taiwan to thenortheastern SCS (Fig. 2) suggests a provenance-controlled consistencyin the clay mineral assemblage. Both the active accretionary prism eastof the Manila trench and the passive continental margin west of theManila trench receive illite and chlorite all from southwestern Taiwan,not depending on their tectonic settings. The dominating illite andchlorite results are generally in accordance with a few literature datagenerated from surface sediments off southwestern Taiwan (Jiang et al.,2006) and river sediments in western Taiwan (Wan et al., 2007). Buttheir direct comparison is not allowed because the weighting factors of

Table 2Average clay mineral assemblages of various regions in southwestern Taiwan, the Pearl Riv

Region Sample number Chlorite Illite

(%) (%)

SW Taiwan rivers 19 43 55SW Taiwan lakes 5 42 55SW Taiwan shelf 11 41 59E Manila trench 87 39 56W Manila trench 18 39 54Pearl River 38 25 26Luzon rivers 7 2 1S China shelf 16 30 37S China slope 7 19 26

Illite chemistry index and illite crystallinity of the Luzon river samples were not measurablethe shelf and slope of South China from Liu et al. (2003) and Boulay et al. (2004, 2005).

Biscaye (1965) were used by the latter two studies. However, an earlierinvestigation on shelf sediments in the Taiwan Strait generated muchhigher smectite and kaolinite contents of 10–40% and 5–9%, respectively(Eisma et al., 1995). They applied the very different analytical andcalculational methods that greatly increased the smectite content,preventing our clay mineral data from their direct comparison.

The Taiwan-sourced claymineral assemblage is obviously differentfrom the ones in the Pearl River drainage basin, in the Luzon rivers,and on the shelf and slope of South China (Fig. 3). The Taiwan-sourcedclays are chiefly illite (average 56%) and chlorite (41%) with scarcekaolinite and smectite, the Pearl River sediments consists mainly ofkaolinite (46%), illite (26%), and chlorite (25%) with scarce smectite(3%) (Liu et al., 2007a,b), whereas clays from the Luzon rivers areprincipally smectite (88%) with minor kaolinite (9%) and scarcechlorite and illite (Table 2). The South China shelf and slope sedimentscontain abundant smectite (19–46%), illite (26–37%), and chlorite (19–

er drainage basin, Luzon, and the northern SCS

Smectite Kaolinite Illite chemistry Illite crystallinity

(%) (%) (°Δ2θ)

1 1 0.33 0.161 2 0.38 0.180 0 0.36 0.163 2 0.35 0.165 2 0.35 0.163 46 0.62 0.30

88 9 / /19 13 0.54 0.2446 9 0.51 0.23

because their illite is very scarce. Data of the Pearl River from Liu et al. (2007a,b); data of

Fig. 5. Correlations of illite crystallinity with kaolinite (%) of surface sediments insouthwestern Taiwan, the Pearl River, and the northern SCS. The coarse dash line showsa linear correlation between illite crystallinity and kaolinite content.

Fig. 4. Correlations of illite chemistry index with illite crystallinity of surface sedimentsin southwestern Taiwan, the Pearl River, and the northern SCS. The coarse dash lineshows a linear correlation between illite chemistry index and illite crystallinity.

Fig. 3. Comparison of clay mineral assemblages among southwestern Taiwan, the PearlRiver, Luzon, and the northern SCS. Data of the Pearl River from Liu et al. (2007a,b), dataof the shelf and slope of South China from Liu et al. (2003) and Boulay et al. (2004, 2005).

153Z. Liu et al. / Marine Geology 255 (2008) 149–155

30%) with minor kaolinite (9–13%), with increasing smectite anddecreasing illite and chlorite seawards (Liu et al., 2003; Boulay et al.,2004, 2005). The physical segregation during sedimentation of clayminerals is not remarkable and can't play a major impact on theirplanar distribution in the northern SCS (Liu et al., 2007a). Therefore,these variations indicate that Taiwan discharges sediments character-ized by abundant illite and chlorite and no kaolinite and smectite tothe northern SCS. Instead, the Pearl River provides abundant kaoliniteand no smectite, and Luzon provides mainly smectite to the sea.

Illite and chlorite on the shelf and slope of South China may also bederived from the Pearl River, where average illite and chlorite contentsare 26% and 25%, respectively (Table 2). But the illite contents on theshelf (37%) and slope (26%) are higher than or equal to the Pearl Rivervalues (Table 2), precluding the Pearl River as a uniquemajor source forillite. Because illite and chlorite in the SCS are considered to have samesources for both surface sediments and geological records (e.g., Chen,1978; Liu et al., 2003, 2004), we here further determine the source ofillite in the northern SCS to account for the provenance of combinedillite and chlorite. Illite chemistry index and illite crystallinity of allmentioned samples are employed, because the two indicators presentnot only hydrolysis conditions of illite (Esquevin, 1969; Krumm andBuggisch, 1991) but also source regions and transport paths (Petschicket al., 1996). A linear correlation of illite chemistry index with illitecrystallinity exists for surface sediments on the South China shelf andslope and in two major potential source areas, the Pearl River andsouthwestern Taiwan (Fig. 4). A higher illite chemistry index cor-responds to a lower illite crystallinity (a higher value), indicating astronger hydrolysis, and vice versa. The Pearl River and southwesternTaiwan actually serve as two end-members of the hydrolysis conditionand then illite provenance. The Pearl River drainage basin undergoesan intensive weathering affected by warm climate with heavy mon-soon precipitation and stable tectonics as well (Liu et al., 2007b), and,therefore, provides abundant Al-rich illite (Fig. 4). Though Taiwan has asimilar subtropical East Asian monsoon climate, the major and traceelement geochemistry suggests only a moderate chemical weatheringdue mainly to extremely high erosion rates triggered by earthquakeand storm activities (Selvaraj and Chen, 2006). The high physicalweathering rate in Taiwan is consistent with present illite chemistryindex and illite crystallinity data with complete Fe–Mg-rich illite. Theillite in the shelf and slope sediments of South China is in the mid-waybetween the two end-members withmore Fe–Mg-rich illite seawards,indicating a gradual decrease in the illite contribution from the Pearl

River and an increase contribution from southwestern Taiwan. Inconsideration of average illite crystallinity values of 0.16°Δ2θ for theTaiwan-sourced samples, 0.23°Δ2θ for the South China slope samples,0.24°Δ2θ for the South China shelf samples, and 0.30°Δ2θ for the PearlRiver samples (Table 2),we approximately calculate the combined illiteand chlorite contribution ratio of southwestern Taiwan to the PearlRiver as 3:4 for the South China shelf and as 1:1 for the South Chinaslope (Fig. 4).

A large volume of basalt is present in the volcanic Luzon Arc(Commission for the Geological Map of the World, 1975) and couldrepresent, byweathering, a huge amount of smectitewith average 88%in rivers of Luzon. The Luzon provenance, therefore, is suggested toaccount for all smectite contribution in sediments on the South Chinashelf and slope (19% for the South China shelf and 46% for the SouthChina slope, Table 2). Assuming that kaolinite in the northern SCS isprovided completely from the Pearl River, a linear correlation of illitecrystallinity with kaolinite (%) is observed for all surface sediments,with two end-members of the Pearl River and Taiwan sources andtransitional South China shelf and slope sediments (Fig. 5). Taking intoaccount the kaolinite contents (Table 2), the combined illite andchlorite contribution ratios, and the unique smectite source of Luzon,we estimate the contributions of clay minerals as 52% from the PearlRiver and 29% from Taiwan to the South China shelf, and as 31%from the Pearl River and 23% from Taiwan to the South China slope(Figs. 5 and 6).

Fig. 6. Semi-quantitative estimation of detrital fine-grained sediment contributions to the northern SCS from Taiwan, the Pearl River, and Luzon, respectively. The deep North PacificDeep Water (NPDW) after Lüdmann et al. (2005), the surface Kuroshio Current (KC) after Caruso et al. (2006).

154 Z. Liu et al. / Marine Geology 255 (2008) 149–155

Thus, the Pearl River contributes approximately half of its clayminerals to the South China shelf and only one third of clay minerals tothe slope,whereas southwesternTaiwan contributes aboutone fourth ofits clay minerals to both the shelf and slope (Fig. 6). The results haveraised a question: how are the Taiwan-sourced clays delivered to theSouth China shelf and slope with a much higher percentage thanpreviously thought?As thewestward branches of theNorth PacificDeepWater (NPDW) and the Kuroshio Current (KC) in the western Pacificcross the Bashi Strait, theymay transport the Taiwan-sourced sedimentsto the northern SCS. Lüdmann et al. (2005) suggested a branch of thesouthward deep NPDW crossing the Bashi Strait and carrying easternand southern Taiwan-sourced re-suspended fine sediments into thenorthern SCS (Fig. 6). The westward deep currents are then pushedupslope at the southeast slope of the Dongsha Islands and releasesediments to form high sedimentation-rate drifts on the South Chinaslope (Lüdmann et al., 2005). Instead, Shao et al. (2007) considered thebottom currents originated also from the branch of NPDW but movingsouthwestwards along the slope to form high sedimentation-rate driftson sides of NE–SW bottom channels. Recently, high-resolution seismicdata revealed that the high sedimentation-rate drifts are actuallycomposed of a series of sediment waves that have migrated upslope(Zhonget al., 2007), confirming theexistence ofwestwarddeep currentsin front of the South China slope. Despite the absence of observed deep-sea current data, we accept the assumption of the deep-sea currents(Lüdmann et al., 2005) that carry the Taiwan-sourced sediments to theSouth China slope. In addition, a branch of the northward surfaceKuroshio Current (KC) may also transport suspended Taiwan-sourcedsediments westwards when it enters into the SCS through the BashiStrait (Caruso et al., 2006). The current is also one of most importantcarriers accounting for smectite contribution to the northern SCS fromthe Luzon Arc and the western Philippine Sea (Wan et al., 2007).

5. Conclusions

Our results indicate that the clay mineral assemblage of surfacesediments in major rivers and lakes in southwestern Taiwan and on

the seafloor off Taiwan in the northeastern SCS consists dominantlyof illite (average 56%) and chlorite (41%), with very scarce kaoliniteand smectite. Their respective distribution from the rivers and lakesto the shelf, accretionary prism, and passive continental margin onthe seafloor off Taiwan does not show obvious basin-wide differ-ences. By combining with clay mineral records of the Pearl Riverdrainage basin, the Luzon rivers, and the South China shelf and slopeand assuming that kaolinite in the northern SCS is providedcompletely from the Pearl River, the linear correlations of illitechemistry index with illite crystallinity and of illite crystallinity withkaolinite (%) are observed for all surface sediments, with two end-members of the Pearl River and Taiwan sources and transitionalSouth China shelf and slope sediments. The contribution of Taiwan inclay minerals is semi-quantitatively evaluated as 29% to the SouthChina shelf and 23% to the South China slope, respectively.Accordingly, the contribution of the Pearl River to the South Chinashelf and slope is 52% and 31%, respectively. The Luzon Arcaccounts for the rest of clay mineral components for the northernSCS mainly by providing smectite. The Bashi Strait-crossed branchesof the southward deep NPDW and the northward surface KC maytransport Taiwan-sourced suspended sediments westwards to thenorthern SCS.

Acknowledgments

Wethank theCentralGeological Surveyof Taiwan toprovide samplesoff SW Taiwan for this study, and Hailing Ren and Hui-Ling Lin forassistance in collecting the samples. We specially thank Gert J. De Langeand two anonymous reviewers for their constructive reviews on theearly version of this paper. This study was supported by the NationalBasic Research Program of China (2007CB815906), the National NaturalScience Foundation of China (40776027 and 40621063), the ShanghaiRising-Star Program (07QH14014), the Shanghai Shuguang Program(07SG23), the Fok Ying Tung Education Foundation (101018), and theDoctoral Program of Higher Education of the Ministry of Education ofChina (20060247032) to Z. Liu. Partial funding for this study was

155Z. Liu et al. / Marine Geology 255 (2008) 149–155

provided by the Taiwan National Science Council (NSC 94-2611-M-110-002 and NSC 95-2745-M-110-001) to J.T. Liu.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, inthe online version, at doi:10.1016/j.margeo.2008.08.003.

References

Biscaye, P.E., 1965. Mineralogy and sedimentation of recent deep-sea clay in the AtlanticOcean and adjacent seas and oceans. Geol. Soc. Am. Bull. 76, 803–832.

Boulay, S., Colin, C., Trentesaux, A., Pluquet, F., Bertaux, J., Blamart, D., Buehring, C.,Wang, P., 2003. Mineralogy and sedimentology of Pleistocene sediment in theSouth China Sea (ODP Site 1144). In: Prell, W.L., Wang, P., Blum, P., Rea, D.K.,Clemens, S.C. (Eds.), Proc. ODP Sci. Result, vol. 184, pp. 1–21. [Online]. Available:http://www-odp.tamu.edu/publications/184_SR/. [Cited 04-2003].

Boulay, S., Colin, C., Trentessaux, A., Frank, N., Liu, Z., Yim, W.W.S., 2004. Variations ofterrigeneous sediment supply associated with the East-Asian monsoon intensity—

implications for sedimentary sources and South China Sea currents. Abstracts of 8thInternational Conference on Paleoceanography, 5–10 September 2004, Biarritz,France, pp. 136–137.

Boulay, S., Colin, C., Trentesaux, A., Frank, N., Liu, Z., 2005. Sediment sources and East Asianmonsoon intensity over the last 450 kyr — mineralogical and geochemicalinvestigations on South China Sea sediment. Palaeogeogr. Palaeoclimatol. Palaeoecol.228, 250–277.

Bühring, C., Sarnthein,M., Erlenkeuser, H., 2004. Toward a high-resolution stable isotopestratigraphy of the last 1.1 m.y.: Site 1144, South China Sea. In: Prell, W.L., Wang, P.,Blum, P., Rea, D.K., Clemens, S.C. (Eds.), Proc. ODP Sci. Result 184, 1–29 [Online].Available: http://www-odp.tamu.edu/publications/184_SR/. [Cited 10-2005].

Caruso, M.J., Gawarkiewicz, G.G., Beardsley, R.C., 2006. Interannual variability of theKuroshio intrusion in the South China Sea. J. Oceanogr. 62, 559–575.

Chamley, H., 1989. Clay Sedimentology. Springer, New York. 623 pp.Chen, P.-Y., 1978. Minerals in bottom sediments of the South China Sea. Geol. Soc. Am.

Bull. 89, 211–222.Clift, P., Lee, J.I., Clark, M., Blusztajn, J., 2002. Erosional response of South China to arc

rifting andmonsoonal strengthening; a record from the South China Sea. Mar. Geol.184, 207–226.

Commission for the Geological Map of the World, 1975. Geological World Atlas, scale1:10000000, U. N. Educ. Sci. and Cult. Org., Paris.

Dadson, S.J., Hovius, N., Chen, H., Dade, W.B., Hsieh, M.-L., Willett, S.D., Hu, J.-C., Horng,M.-J., Chen, M.-C., Stark, C.P., Lague, D., Lin, J.-C., 2003. Links between erosion, runoffvariability and seismicity in the Taiwan orogen. Nature 426, 648–651.

Ehrmann, W., 1998. Implications of late Eocene to early Miocene clay mineralassemblages in McMurdo Sound (Ross Sea, Antarctica) on paleoclimate and icedynamics. Palaeogeogr. Palaeoclimatol. Palaeoecol. 139, 213–231.

Eisma, D., Ji, Z., Chen, S., Chen, M., van der Gaast, S.J., 1995. Clay Mineral Composition ofRecent Sediment along the China Coast, in the Yellow Sea and the East China Sea.Nederlands Instituut voor Onderzoek der Zee (NIOZ) Rapport 1995-4. 13 pp.

Esquevin, J., 1969. Influence de la composition chimique des illites surcristallinite. Bull.Centre Rech. Rau-SNPA 3 (1), 147–153.

Gingele, F.X., Müller, P.M., Schneider, R.R., 1998. Orbital forcing of freshwater input in theZaire Fan area — clay mineral evidence from the last 200 kyr. Palaeogeogr.Palaeoclimatol. Palaeoecol. 138, 17–26.

Hiscott, R.N., 2001. Depositional sequences controlled by high rates of sediment supply,sea-level variations, and growth faulting: the Quaternary Baram Delta of north-western Borneo. Mar. Geol. 175, 67–102.

Holtzapffel, T., 1985. Les Minéraux Argileux: Préparation, Analyse Diffractométrique etDetermination. Soc. Géol. Nord Publ., vol. 12. 136 pp.

Huang, W., 2004. Sediment Distributional Patterns and Evolution in the South China Seasince the Oligocene. Doctoral Dissertation. Shanghai: Tongji University. 113 pp.

Huang, C.-Y., Yuan, P.B., Tsao, S.J., 2006. Temporal and spatial records of active arc-continent collision in Taiwan: a synthesis. Geol. Soc. Am. Bull. 118, 274–288.

Jiang,W.-T., Chen, J.-C., Huang, B.-J., Chen, C.-J., Lee, Y.-T., Huang, P.-R., Lung, C.-C., Huang,S.-W., 2006. Mineralogy and physical properties of cored sediments from the gas

hydrate potential area of offshore southwestern Taiwan. Terr. Atmos. Ocean. Sci.17 (4), 981–1007.

Krumm,S., Buggisch,W.,1991.Samplepreparationeffectson illite crystallinitymeasurements:grain size gradation and particle orientation. J. Metamorph. Geol. 9, 671–677.

Lambiase, J.J., bin Abdul Rahim, A.A., Peng, C.Y., 2002. Facies distribution andsedimentary processes on the modern Baram Delta: implications for the reservoirsandstones on NW Borneo. Mar. Petrol. Geol. 19, 69–78.

Li, X.-h., Wei, G., Shao, L., Liu, Y., Liang, X., Jian, Z., Sun, M., Wang, P., 2003. Geochemicaland Nd isotopic variations in sediments of the South China Sea: a response toCenozoic tectonism in SE Asia. Earth Planet. Sci. Lett. 211, 207–220.

Liu, Z., Trentesaux, A., Clemens, S.C., Colin, C., Wang, P., Huang, B., Boulay, S., 2003. Claymineral assemblages in the northern South China Sea: implications for East Asianmonsoon evolution over the past 2 million years. Mar. Geol. 201, 133–146.

Liu, Z., Colin, C., Trentesaux, A., Blamart, D., Bassinot, F., Siani, G., Sicre, M.-A., 2004.Erosional history of the eastern Tibetan Plateau over the past 190 kyr: claymineralogical and geochemical investigations from the southwestern South ChinaSea. Mar. Geol. 209, 1–18.

Liu, Z., Colin, C., Trentesaux, A., Siani, G., Frank, N., Blamart, D., Farid, S., 2005. LateQuaternary climatic control on erosion and weathering in the eastern TibetanPlateau and the Mekong Basin. Quat. Res. 63, 316–328.

Liu, Z., Colin, C., Huang, W., Chen, Z., Trentesaux, A., Chen, J., 2007a. Clay minerals insurface sediments of the Pearl River drainage basin and their contribution to theSouth China Sea. Chin. Sci. Bull. 52 (8), 1101–1111.

Liu, Z., Colin, C., Huang, W., Le, K.P., Tong, S., Chen, Z., Trentesaux, A., 2007b. Climatic andtectonic controls on weathering in South China and the Indochina Peninsula: claymineralogical and geochemical investigations from the Pearl, Red, and Mekongdrainage basins. Geochem. Geophys. Geosyst. 8, Q05005. doi:10.1029/2006GC001490.

Lüdmann, T., Wong, H.K., Berglar, K., 2005. Upward flow of North Pacific Deep Water inthe northern South China Sea as deduced from the occurrence of drift sediments.Geophys. Res. Lett. 32, L05614. doi:10.1029/2004GL021967.

Milliman, J.D., Syvitski, J.P.M., 1992. Geomorphic/tectonic control of sediment dischargeto the ocean: the importance of small mountainous rivers. J. Geol. 100, 525–544.

Petschick, R., 2000. MacDiff 4.2.2 [Online]. Available: http://servermac.geologie.un-frankfurt.de/Rainer.html. [Cited 01-12-2001].

Petschick, R., Kuhn, G., Gingele, F., 1996. Clay mineral distribution in surface sedimentsof the South Atlantic: sources, transport, and relation to oceanography. Mar. Geol.130, 203–229.

Selvaraj, K., Chen, C.-T.A., 2006. Moderate chemical weathering of subtropical Taiwan:constraints from solid-phase geochemistry of sediments and sedimentary rocks.J. Geol. 114, 101–116.

Shao, L., Li, X., Geng, J., Pang, X., Lei, Y., Qiao, P., Wang, L., Wang, H., 2007. Deep waterbottom current deposition in the northern South China Sea. Sci. China Ser. D-EarthSci. 50, 1060–1066.

Tamburini, F., Adatte, T., Föllmi, K., Bernasconi, S.M., Steinmann, P., 2003. Investigatingthe history of East Asian monsoon and climate during the last glacial interglacialperiod (0–140,000 years): mineralogy and geochemistry of ODP Sites 1143 and1144, South China Sea. Mar. Geol. 201, 147–168.

Wan, S., Li, A., Clift, P.D., Stuut, J.-B.W., 2007. Development of the East Asian monsoon:mineralogical and sedimentologic records in the northern South China Sea since20 Ma. Palaeogeogr. Palaeoclimatol. Palaeoecol. 254, 561–582.

Wang, L., Sarnthein, M., Erlenkeuser, H., Grimalt, J., Grootes, P., Heilig, S., Ivanova, E.,Kienast, M., Pelejero, C., Pflaumann, U., 1999. East Asian monsoon climate duringthe Late Pleistocene: high-resolution sediment records from the South China Sea.Mar. Geol. 156, 245–284.

Wang, P., Prell, W.L., Blum, P., et al. (Eds.), 2000. Proc. ODP, Init. Rept. 184 [CD-ROM].Available from: Ocean Drilling Program, Texas A&M University, College Station TX77845-9547, USA.

Wang, P., Clemens, S., Beaufort, L., Braconnot, P., Ganssen, G., Jian, Z., Kershaw, P.,Sarnthein, M., 2005. Evolution of variability of the Asian monsoon system: state ofthe art and outstanding issues. Quatern. Sci. Rev. 24, 595–629.

Wehausen, R., Brumsack, H.-J., 2002. Astronomical forcing of the East Asian monsoonmirrored by the composition of Pliocene South China Sea sediments. Earth Planet.Sci. Lett. 201, 621–636.

Zhong, G., Li, Q., Hao, H., Wang, L., 2007. Current status of deep-water sediment wavestudies and the South China Sea perspectives. Advances Earth Sci. 22, 907–913 (inChinese with English abstract).