Sedimentary biogeochemistry and palaeoceanography of the South China Sea during the late Pleistocene

The South China Sea (SCS) is the largest marginal basin off the Asian continent and its surface hydrography as well as sedimentation within the basin are strongly influenced by the SE Asian monsoon and eustatic sea-level changes. This thesis contributes to our understanding of these key aspects of glacial-interglacial palaeoceanography by presenting multi-proxy organic and inorganic sediment geochemical records from a large number of gravity cores and surface sediment samples from throughout the SCS.; A comparison of various geochemical and micropalaeontological methods to estimate palaeo-sea surface temperatures (SSTs) demonstrates a quantitative agreement between alkenone (UK′₃₇), foraminiferal Mg/Ca, and foraminiferal transfer function FP-12E SST estimates in recording an annual average cooling of 2–2.5°C of the tropical southern SCS during the last glacial period.; The nitrogen isotopic composition (δ15N) of surface and down-core sediments spanning the last glacial-interglacial cycle from the entire South China Sea (SCS) has a narrow range (∼3.0 to ∼6.5‰) with no correlation with discernible palaeoclimatic/oceanographic changes.; The carbon isotopic composition of organic matter (δ13C _org) in sediment cores from throughout the open SCS covering the last 220 kyr shows higher values (around −19.5 to −20.5‰) during glacial stages, while lower values (around −21 to −22.5‰) are characteristic of interglacials.; Based on the sedimentological and geochemical variability at core sites along a transect across the outer Sunda Shelf and the continental slope covering the last 20 thousand years, four intervals of significant depositional changes are identified, which closely correlate with environmental shifts on the central shelf.; Major element variations in a core from the northern SCS are used to infer downcore changes in bulk sediment composition, which are interpreted in terms of deglacial changes in monsoonal climate.; Finally, the rapid drop in the supply of terrigenous organic matter to the open SCS also corresponds with a rapid increase in sea-surface temperature during the last deglaciation, corresponding with the Bølling warming at 14.7 kyr B.P. (Abstract shortened by UMI.)...