GEOCHEMICAL EVIDENCE OF HOLOCENE EAST ASIAN MONSOON VARIABILITY FROM SUNDA SHELF, SOUTH CHINA SEA SEDIMENTS
In 2008, mud-dominated piston cores D42 (3.88 m long, 52.33 m water depth) and D45 (2.68 m long, 62.51 m water depth) were collected in fluvial paleochannels on the Sunda Shelf approximately 80 km northwest of Bintulu, Sarawak, Malaysia. Twenty-nine AMS radiocarbon age estimates of the benthic foraminifer Cavarotalia annectens provide age control. Core D45, collected on the edge of a v-shaped paleochannel, yields a ca. 7,000 year record, while core D42, collected in a shallower paleochannel, reflects ca. 3,000 years of accumulation. Mg/Ca ratios of planktonic foraminifera Globigerinoides ruber and Globigerinoides sacculifer, in combination with δ18O of G. ruber, allow for the analysis of sea surface temperature and salinity trends that may be related to EAM variability. Temperatures were calculated from Mg/Ca values using a warm water, multi-species approach. δ18Oseawater was calculated from temperature and δ18Ocalcite using a high light equation. Finally, these values were transformed into salinities. Additionally, stable carbon isotopic analysis of both G. ruber and C. annectens provides information regarding continental runoff as well as surface and bottom water mixing.