Download Abstract - Coastal Geology and Process Laboratory

Tracing the source to sink patterns of river sediments in East Asian marginal seas by
using geochemical methods
Shouye Yang 1, Yanguang Dou 1, Chao Li 1, Zhenxia Liu 2, Hua Yu3
1
State Key Laboratory of Marine Geology, Tongji University, Shanghai, China ([email protected])
2 First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, PR China
3 Department of Earth Sciences, Rice University, Houston, TX 77005, USA
The mega-rivers originated from the Himalayan-Tibetan Plateau transport huge amount of
particulate and dissolved matters from the plateau and its surrounding continents into the marginal
seas of Asia and, therefore, exert a great control on source to sink process of terrigenous materials.
East Asian marginal seas such as the East China Sea and the Yellow Sea can be regarded as natural
research laboratories for the studies of late Quaternary paleoenvironmental changes and land-sea
interactions. Recognition of the source-to-sink history and dispersal patterns of river-borne
sediments in East Asian marginal seas is very important for paleoenvironmental reconstruction.
The Changjiang (Yangtze River) and Huanghe (Yellow River) as the two largest rivers in East
Asia have increasingly attracted world-wide research attentions during the past decades. Over the
past ten years, we systematically studied sedimentary geochemical compositions of both rivers.
We found that the specific source rocks in the drainage basins contribute significantly to
geochemical compositions of the river sediments into the seas. The REE and Sr-Nd-Pb isotopic
compositions and age spectrum of zircon and monazite grains in the bulk and size-separated
fractions of river sediments provide good constraints on sediment recycling and evolution of
weathered upper continental crust in the large drainage basins. Geochemical proxies such as
(La/Yb)UCC, (La/Gd)UCC, εNd, and age patterns of detrital zircon grains can thus be established for
discriminating different river sediment sources in the marginal seas.
Case studies in the Yellow Sea and East China Sea revealed that geochemical approaches can
successfully identify the sediment origins and investigate the late-Quaternary transport patterns of
the Changjiang- and Huanghe-derived sediments in the seas. Nevertheless, the reconstruction of
the source-to-sink history of the river-borne sediments in these marginal seas can be complicated
by the combined influences of natural climatic variability, sea level and oceanic current changes,
volcanic eruptions, and anthropogenic activities on the production, transport, deposition and
preservation of terrestrial sediments. It should be cautious to interpret the late Quaternary
paleoenvironmental records in the Asian marginal seas due to the intense river-sea interactions and
probably discontinuity in the sedimentary strata.
ACKNOWLEDGEMENT
This work was supported by research funds awarded by the National Natural Science Foundation
of China (No. 40676031) and by Program for New Century Excellent Talents in Universities (No.
NCET-06-0385).