Sediment transport and reworking in the Pearl River and the northern South China Sea shelf

Author(s): Clift, Peter D.; Hu, Dengke; Böning, Philipp; Wan Shiming; Hillier, Stephen
Author Affiliation(s): Primary:
Louisiana State University, Department of Geology and Geophysics, Baton Rouge, LA, United States
University of Aberdeen, United Kingdom
Carl von Ossietzky University, Germany
Chinese Academy of Sciences, Institute of Oceanology, China
James Hutton Institute, United Kingdom
Volume Title: 34th international geological congress; abstracts
Source: International Geological Congress [International Geological Congress, Abstracts = Congrès Géologique International, Résumés, Vol.34, p.2900; 34th international geological congress, Brisbane, Queensl., Australia, Aug. 5-10, 2012. Publisher:], [location varies], International CODEN: IGABBY
Note: In English
Summary: The northern margin of the South China Sea receives sediment dominantly from small mountainous rivers on the island of Taiwan and from the Pearl River. Provenance analysis of sediment from ODP wells in the NE corner of the basin shows an overwhelming flux from Taiwan. Sediment deposited during the Holocene on the continental margin shows more intense chemical weathering compared to that during the LGM. However, hematite/goethite ratios argue for dry conditions despite the known strong summer monsoon at that time. This indicates that the sediment reaching the slope is reworked from the exposed shelf rather than being derived directly from Taiwan. Strong rains eroded the sediments that had been weathering slowly but over a long time period around the Taiwan Strait, until the region was submerged by rising sea levels after 8 ka. The weathering response to climate change is thus an inherited rather than a direct one. In the Pearl River delta itself Sr isotopes shows a clear and unbuffered record with strong monsoon rains linked to stronger chemical weathering. Surprisingly the material now in the river and deposited in the delta after 2000 years ago shows a marked rise in weathering intensity despite little change in monsoon strength. We suggest that this change is driven by human settlement of the Pearl River region and the erosion of older weathered soils by the initiation of agriculture.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; Agriculture; Alkaline earth metals; Asia; Cenozoic; China; Continental shelf; Deposition; Erosion; Far East; Fluvial features; Guangdong China; Holocene; Isotope ratios; Isotopes; Marine sediments; Metals; Monsoons; North Pacific; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; Pearl River; Quaternary; Rivers; Sediment transport; Sediments; Sr-87/Sr-86; Stable isotopes; Strontium; Taiwan; Taiwan Strait; Transport; Weathering; West Pacific; Zhujiang River
Coordinates: N000000 N250000 E1220000 E0991000
Record ID: 2015014200
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