Shouye YANG , Yanguang DOU, Chao LI

1. International Sediment Trap Workshop and Symposium on Sediment Transport and Sediment on Asian Margins, 23-27 March, 2009 Taiwan Tracing the source to sink patterns of river sediments in East Asian marginal seas by using geochemical methods Shouye YANG, Yanguang DOU, Chao LI State Key Laboratory of Marine Geology, Tongji University, Shanghai, China Zhenxia LIU, Hua YU The First Institute of Oceanography, SOA, Qingdao, China

2. Talk outline • Research background • How to identify the river sediments? • Case study: — Discriminations of sediment sources of the Okinawa Trough during the late Quaternary

3. Tibet uplift Monsoon evolution & river evolution Source to sink Key questions: Provenance weathering, Chemical flux, Sediment recycling at present and in the geological past

4. Source to sink Japan Sea Huanghe R. Yellow Sea Cheju Strait ? East China Sea Changjiang R. Okinawa Trough Huge sediments derived from mega-rivers dominate the sedimentation of the western Pacific marginal seas.

5. 2004.7 primary productivity Freshwater transport from the Changjiang to the Japan Seacould significantly affect the primary production & deep circulation in the Japan Sea. Suspended particles? Senjyu, T et al. (2006, senjyu@riam.kyushu-u.ac.jp) Asanuma et al., 2005

6. Sediment flux in the Yellow Sea The S2S pattern of river sediments in the Yellow Sea is very complex and much variable during the late Quaternary, which is a big challenging problem for the paleoenvironmental reconstruction. Unit: 108 ton/yr Yang et al. (2003) Earth-Science Review

7. Potential sediment provenances in the shelf and open sea Siliciclastic sediments: S2S

8. Sediment samples and analytic methods

9. Samples from the Changjiang (Yangtze River) (suspended, bed, floodplain) Upper reaches Middle reaches Lower reaches

10. The first bend of the Changjiang at Shigu NW NE Daduhe and Minjiang Rivers Wujiang River Field work in the Changjiang, 2003-2007

11. The Upper Reach:Jinshajiang Riverat Lijiang, Yunnan Province The Lower Reach

12. Huanghe: Yellow River

13. Case study: Okinawa Trough Core DGKS9604: Location: west slope of the middle Okinawa Trough Water depth: 766 m Core length: 10.76 m (~30 Cal Ka) Recovery: about 95% Sediment S2S pattern of the Okinawa Trough during the late Quaternary

14. Analytic methods • Sample pre-treatment： <0.063mm fine-grained samples (elements) 1 N HCl leaching experiment (element & Sr-Nd-Pb isotopes) • REE and elements：ICP-MS/ES • Sr-Nd-Pb isotopes： — TIMS（modern sediments） — MC ICP-MS （Core sediments） • Mineral chemistry (zircon, garnet, apatite, monazite)

15. Geochemical proxies of sediment provenance discrimination — REE fractionation pattern and parameters including (La/Yb)UCC, (Gd/Yb)UCC, (La/Sm)UCC, δCe, δEu — Ratios of conservative elements such as La/Sc, Th/Sc, Ti/Nb, Cr/Th, Ti/Al….. — Sr-Nd-Pb isotopic systematics — Mineral chemistry of detrital zircon, monazite, Ti-Fe oxides and garnet grains

16. Talk outline • Research background • How to identify the river sediments? • Case study: — Discriminations of sediment sources of the Okinawa Trough during the late Quaternary

17. 1N HCl leaching residual fraction Yalongjiang Fujiang Jinshajiang Rare earth elemental compositions in the Changjiang sediments UCC: upper continental crust, T & M, 1985

18. The Korean river sediments are relatively more enriched in LREE than Chinese river sediments, suggesting different source rock compositions in their drainage basins. Yang, et al. (2002) EPSL

19. Chinese Rivers Korean rivers Characteristic REE parameters and elemental ratios can be treated as reliable geochemical proxies to trace the river sediment sources. Chinese Rivers Korean rivers Yang et al., Earth-Science Review, 2003; Chinese Sci Bull., 2004

20. Korean rivers Chinese rivers Geochemical proxies for discriminating Chinese and Korean river sediments Chinese rivers Korean rivers Yang et al., Earth-Science Review, 2003; Chinese Sci Bull., 2004

21. Sr-Nd isotopic compositions of the Changjiang suspended sediments Yang et al., Sci in China, 2007

22. Comparison of Sr-Nd isotopes

23. Distinct isotopic compositions exist between East Asian river sediments

24. 1N HCl-leached fractions of the river sediments show good discrimination results between Chinese and Korean river end-members. Choi et al. 2007. Marine Chemistry

25. Detrital zircon grains from the Changjiang river sediments

26. Mineral chemistry of detrital zircon grains from the Changjiang sediments

27. Zircon ages of the Changjiang sediments

28. Monazite age spectrum of the Changjiang sediments

29. Controls of sedimentary geochemical compositions • Provenance rocks character：age, type, outcrop area, weathering rate • Chemical fractionation of minerals during chemical weathering • Hydrodynamic sorting during transport and deposition：grain size effect, SPM representative • Sediment recycling：complex but important • Sample treatment：1 N HCl, residual fraction

30. Source rocks in the Changjiang drainage basin

31. Sr isotopic compositions in the source rocks of the Changjiang drainage basin Increasing ages

32. Nd isotopic compositions in the source rocks of the Changjiang drainage basin

33. Acidic igneous rocks dominant in the Korean river basins. Different climate regimes result in variable weathering intensities.

34. Case study Sediment provenances of the middle Okinawa Trough during the last 30 Cal ka Core DGKS9604: Location: west slope of the middle Okinawa Trough Water depth: 766 m Core length: 10.76 m (~30 Cal Ka) Recovery: about 95%

35. δ Large changes occur in the deglacial period

36. REE: abrupt changes occur at ca. 8 ka

37. REE fractionation patterns Tephra layer

38. Sr-Nd isotopes abrupt changes occur at 8 ka Unit 1 Unit 2

39. Different sediment sources Unit 1: 0~ 7.1 ka Taiwan Source? Unit 2: 8.2~31 ka Changjiang-sediments dominated Dou et al., submitted Aira caldera data after Arakawa et al. (1998); Volcanic rocks data after Shinjo and Kato (2000)

40. ~150 Mt/yr Shuh-Ji Kao, et al., 2005. TAO

41. 0~7 ka BP Variable sediment sources with time ~ LGM

42. Thanks!