Late quaternary deep-water circulation in the South China Sea

Abstract

A suite of four new benthic foraminiferal (Cibicidoides wuellerstorfi) stable carbon isotope records produced from South China Sea (SCS) sediment cores ranging in water depth from 1515 and 3766 m are used here to evaluate deep-water circulation in the SCS over the last complete glacial-interglacial cycle (i.e., the last 200 kyrs). A common pattern of benthic δ13C variations is observed between cores, with pronounced δ13C depletions recorded during glacial periods and δ13C enrichments during interglacials. The overall similarity of δ13C values between sites indicates a homogeneous water mass below 1500 m in the SCS basin through time, except for the interval between 120 and 65 ka. Temporal changes in ventilation and exchange between the SCS and western Pacific are indicated by comparison with records from the Ontong Java Plateau (OJP). The presence of Pacific Intermediate Water can be inferred based on the bathymetric gradient of δ13C between SCS and OJP (Δδ13C). The Δδ13C patterns do not appear to be correlated with glacial-interglacial cycles. However, the Δδ18O is greater in warm intervals (late MIS 4 and early MIS 3; MIS 1) than during cold intervals.