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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 δO 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, 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 records abrupt climate change events more clearly. SST 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. [ABSTRACT FROM AUTHOR]

Reports on the Ocean Drilling Program (ODP) Leg 184 Shipboard Party, which cored 17 holes at 6 deep water sites in the northern and southern parts of the South China Sea (SCS). Participation of Chinese scientists in this deep-sea drilling leg off China; Number of analyses on core samples conducted post-cruise; Mention of three papers reporting the major scientific achievements of the Leg 184 studies; One dealing with deep-sea stratigraphy and evolution of climate cycles; Discoveries of this ODP leg, including deep-sea stratigraphic sequences in the Western Pacific; The unique status of the 23-Ma isotope sequence from the Dong-Sha area and the last 5-Ma sequence from the Nansha area; How the sequences of physical properties are linked to the decadal-scale time resolution; Contribution of these marine stratigraphic records to paleoenvironmental studies; Finding of changes in climate cyclicity over the last 20 Ma that points to the climate system's evolving response to orbital forcing, as well as growth of the Antarctic and Northern Hemisphere ice sheets.

Studies the carbonate dissolution and deep-water paleoceanography of gravity Core 17957-2 from the southern South China Sea. Chronology of the core; Indication of calcium carbonate dissolution during the transition from interglacial to glacial stages; Comparison to the cyles of carbonate dissolutions of the Indian Ocean.

Examines the variations of opal accumulation rates and paleoproductivity over the past 12 Ma at ODP 184 site 1143, southern South China Sea. Increase of the opal content; Reflection of the high biogenic productivity in the late Miocene in the southern South China Sea; Influence of the enhanced upswelling and nutrient supply on the increase of opal content.

Abstract: The hydrography of the South China Sea (SCS) is characterized by a south–north (S–N) thermocline gradient in the upper water column from the northern margin of the western Pacific warm Pool (WPWP) to the sea area largely controlled by the East Asian monsoon. Here we examine the records of planktonic foraminifers from Ocean Drilling Program (ODP) Sites 1143 and 1146 in the southern and northern parts of the SCS, respectively, that identify three stages of evolution of the S–N hydrographic gradient in the SCS since the middle Miocene: first, the S–N thermocline gradient possibly occurred in the SCS for the first time during the period 11.5∼10.6 Ma, reflected by an opposite change in the relative abundance of deep-dwelling planktonic foraminiferal species in the south and north; next, the S–N thermocline gradient weakened or even disappeared during the period 10.6∼4.0 Ma, indicated by similar changes in the relative abundance of deep-dwelling species in the south and north; last, the S–N thermocline gradient substantially increased from about 4.0∼3.2 Ma, marked by a major increase in abundance of deep-dwelling species in the northern SCS and a decrease in the southern SCS. Based on the results of oceanic and coupled ocean–atmosphere model experiments and previous studies on planktonic foraminifers in the Pacific Ocean, it is inferred that the initial WPWP was probably formed during the period of 11.5∼10.6 Ma in response to the closure of the Indonesian seaway; The WPWP then weakened or became extremely unstable, before developing its present expression about 4.0–3.2 Ma, induced by the emergence of the Isthmus of Panama. Our observations and model experiments support the argument that the stages in evolution of the WPWP are linked to tectonic changes in ocean gateways. [Copyright &y& Elsevier]

Abstract: A high resolution record (∼1100 yr) of planktonic foraminifers from ODP Site 1144 in the northern South China Sea reveals rapid and strongly variable climatic changes during the mid-Pleistocene transition period. The abundance of warm water species decreased from an average of 60% in marine isotope stage (MIS) 29 to <40% at MIS 22, followed by a steady increase in cool water species toward younger intervals. Many deep dwelling, warm water species decreased to a minimum during MIS 22 and remained extremely rare or even became absent in younger glacial intervals, indicating stepwise sea surface cooling in the region. Estimated SSTs show large fluctuations mostly at glacial–interglacial transitions. A maximum winter temperature difference of 11 °C (17–28 °C) across MIS 23/22 boundary likely corresponded to a major growth of boreal ice sheets across the MPT center at 0.9 myr, coupled with a strengthened winter monsoon over East Asia . The MPT event not only led to a better correlation between changes in species abundances and glacial–interglacial cycles but also a more constrained thermocline that shoaled considerably during subsequent glacial periods. The oxygen isotope record and the abundance of shallow water species display power spectra closely in pace with the 41,000 and 100,000 years cyclicities. A lower coherence over these cyclicities between deep-water dwelling species and the planktonic δ 18O, a shoaled thermocline, and more pisitive glacial δ 18O together suggest disturbances of surface and subsurface waters by intensified winter monsoons over the last 1.1–0.5 myr in the South China Sea. [Copyright &y& Elsevier]