Abstract
Variations in sea surface temperature (SST), productivity, and biogenic components such as total organic carbon (TOC), carbonate, and opal contents measured from IMAGES (International Marine Global Changes Study) core MD972142 provide information about long-term paleoceanographic changes during the past ~870000 years in the southeastern South China Sea (SCS). MD972142 U 37 -SSTs varied from 25 to 29C, paralleling the glacial to interglacial changes. MD972142 biogenic components show relatively high carbonate and opal, and low TOC contents in interglacial stages, and low carbonate and opal and high TOC contents in glacial stages, and these variations appear to be sensitive to regional terrestrial sediment input and productivity. Our analysis indicates that the MD972142 carbonate record is primarily controlled by terrestrial sediment inputs that are associated with sea level fluctuations during past glacial-interglacial stages. The TOC record reflects past glacial-interglacial changes in both monsoon-induced productivity and terrestrial organic matter input in the SCS. The TOC record exhibits several short-term peaks that are associated with lower U 37 -SSTs (especially in MIS 2 - 4, 10, 12), perhaps implying a much strengthened winter monsoon. The opal record shows relatively high content in most interglacial stages, which appears to be linked to increased summer monsoon upwelling or increased siliceous sediment input by more precipitation and river runoff during warm climate conditions. The TOC and opal contents both show long-term increasing trends since the mid-Brunhes, most noticeably from ~330 kya. The long-term trends observed in this study are most likely attributable to changes in SCS hydrography, productivity, and/or preservation in response to the increased strength of the East Asian monsoon system on possibly tectonic timescales.
Highlights
The South China Sea (SCS) is the largest marginal sea in the western Pacific
We do observe carbonate content maxima corresponding to interglacial stages and minima corresponding to glacial stages (Fig. 2)
While comparing this pattern with our preservation index based on foraminifer fragmentation, we found that the carbonate content maxima corresponded to low preservation during most interglacial stages, an impossible relationship if the carbonate content variations are driven by dissolution
Summary
The South China Sea (SCS) is the largest marginal sea in the western Pacific. It is characterized by wide continental shelves to the northwest and south, with voluminous runoff from large rivers, and a deep central basin (water depth ~4700 m). In the summer monsoon seasons, warm Indian Ocean surface waters flow over the Sunda Shelf into the SCS, resulting in relatively high WPWP sea surface temperatures (SST, ~28°C) in the entire SCS’s surface water. During November to March, strong northeast (winter) monsoons from the East Asian continent prevail in the SCS, resulting in a large N-S gradient of SST in the SCS surface water. Strong mixing caused by the winter monsoon winds and cold coastal water intrusion from the north result in high productivity and low SSTs in the northern SCS (Wyrtki 1961; Shaw and Chao 1994)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
