CENTENNIAL TO MILLENNIAL SCALE HYDROGRAPHIC VARIATIONS IN THE NORTHERN AND SOUTHERN SOUTH CHINA SEA DURING THE PAST 10-70 KYR

The South China Sea (SCS) is a place that is influenced by the East Asian Monsoon and Western Pacific Warm Pool (WPWP) systems. The SCS sediments are highly sensitive recorders of past climate in the tropical oceans as its marginal sea location causes it to accumulate sediments rapidly from both marine and terrestrial sources. Here we present a high-resolution sea surface temperature (SST) and salinity (SSAL) records from an IMAGES core MD972151, which is located at the southwestern SCS. The SSTs were estimated by revised planktic foraminifer fauna transfer function and alkenone methods. We calculated the SSAL by deconvoluting the planktic foraminifer ¶18O record into components of temperature, salinity and ice volume components correction. In focusing the past 10-70 kyr variations, we used AMS 14C dating and also age-tuning the ¶18O to match a Hulu cave stalagmite record from the mainland China. Within the uncertainty of our age controls, the MD972151 record reveals high-frequency SSAL variations that varied in accord with Dansgarrd/Oeschger cycles shown in the Hulu Cave stalagmite and the Greenland ice core (GISPII) records. The SSAL estimates were relatively higher during the major episodes of high-latitude cooling and were lower during major interstadials. The patterns of the SSAL estimates are echoed by the variations of a color reflectance proxy for terrestrial precipitation. The precipitation proxy was derived from the first derivative of visible light spectra of sediment surface color, which is indicative of the changing compositions of goethite relative to hematite (G/G+H). The precipitation index shows lower/or arid during the Heinrich-like cooling events, and higher/or moist in major interstadials. The records of SSAL and precipitation index variations provide data supporting the hypothesis calls upon the shift in the tropical Pacific ocean/atmosphere system analogous to modern El Ni–o-Southern Oscillation (ENSO) driving past climate change.