The Major Research Program "Deep Sea Processes and Evolution of the South China Sea", or "The South China Sea Deep", launched in January 2011 by the National Natural Science Foundation of China, is the first large-scale basic-research program in ocean science in the country aiming to reconstruct the life history of a marginal sea. The overall scientific objective of the program is to dissect this typical marginal sea by studying its history of evolution and its modern processes, including the following three major components:(1) Development of the deep basin:utilizing new techniques to re-measure magnetic anomaly lineations, to explore the deep tectonic features, to drill the oceanic crust, and to study volcanic seamount chains; (2) deep-water sediments: observing the modern processes to reveal the patterns of deep-water circulations and sedimentation, analyzing deep-sea sediments to recognize paleoceanographic response to basin evolution, and subsequently to bridge the modern and paleo-studies of the deep-sea processes; and (3) biogeochemical processes:using a variety of techniques including deploying submarine observation and deep-water diving device to investigate the distribution patterns and environmental impacts of deepwater seepages and sub-bottom circulation, and to reveal the role of microbes in deep-sea carbon cycling. As compared with the open ocean and other marginal seas, the South China Sea enjoys many more advantages as a marine basin for reconstructing the life history. Meanwhile, the South China Sea Deep Program provides unique opportunities in studying the evolution and variations of the sea-land interactions between the Pacific and Asia.
Based on the detailed planktonic foraminifera faunal count and Globigerinoides ruber Mg/Ca ratio analysis of Core MD05-2901,we reconstructed the longest Mg/Ca sea surface temperature(SST) sequence of the upwelling area off Vietnam in the western South China Sea(SCS).Ocean environment,especially the SST variation,over the last 450 ka is discussed in this study.SST variation has typical glacial/interglacial alternations from 23.03°C to 29.93°C with a glacial/interglacial difference of 4.8°C on average.SST during the interglacial periods fluctuates significantly,up to 5.6°C,which is larger than the average glacial/interglacial difference.SST variation during the glacial periods is much smaller.Spectrum analysis shows that SST change dominates on the typical Milankovitch cycles,such as 112,40.7 and 23.6 ka.Evident leading of SST variation against the δ 18 O can be observed during the Terminations 1,4,and 5,which is confirmed by their cross-spectrum analysis on these cycles.MD05-2901 is the first core in the South China Sea that has multi-SST records,such as SST Mg/Ca,k' 37 U-SST and planktonic foraminiferal fauna-based SST.SSTs from different methods can be correlated with each other in glacial/interglacial time scale,whereas SST Mg/Ca records abrupt climate change events more clearly.SST Mg/Ca at MD05-2901 since MIS 5 is 0.6°C lower than that of the southern SCS on average,but equivalent to or even 2°C lower than that of the northern SCS during some interglacial period.The SST character of MD05-2901 reflects less influence of latitude,but an important role of the regional upwelling driven by the eastern Asian summer monsoon,and suggests a stronger upwelling during the interglacial periods in the western SCS.
