RECONSTRUCTION OF MID- TO LATE-HOLOCENE PALEOCLIMATE, SUNDA SHELF, OFF NE PENINSULAR MALAYSIA BASED ON MAGNETIC SUSCEPTIBILITY OF BULK SEDIMENT

The East Asian Monsoon (EAM) dominates the climate of the South China Sea (SCS) and the adjacent Southeast Asian mainland, directly affecting Asia’s seasonal patterns of precipitation, runoff, and nutrient transport. Changes in the strength of the EAM system can lead to droughts and flooding events that can negatively impact economic growth and environmental sustainability in the region. Because of its central location within the EAM system, the deep SCS has been the focus for many paleoclimatic reconstructions. However, the shallow, southern SCS (Sunda Shelf) has received comparatively little attention. This research focuses on the record of the EAM preserved in the sediment fill of a paleovalley 30 km offshore of Kuala Terengganu, northeast Peninsular Malaysia.

Magnetic susceptibility of bulk sediment (BMS) was analyzed for two ca. 3 m-long gravity cores, TER-13-GC3 and TER-13-GC4 (ca 50 m water depth). An AMS radiocarbon-based chronology for each core was derived from eight samples of the benthic foraminifer Cavarotalia annectens. Age models were determined using BChron. The sediment record extends back to ca. 5000 cal yr BP in TER-13-GC4 and to 4000 cal yr BP in TER-13-GC3. BMS is a sensitive proxy of sedimentological changes and hence, of sediment provenance that locally might be related to continental sediment runoff and precipitation. Assuming this relationship, four distinct intervals BMS identified in this study likely reflect paleoclimatic changes including two episodes of increased precipitation. BMS data interpretation will be supported with X-ray fluorescence analysis of sediment and oxygen stable isotopic analysis of the planktonic foraminifera Globigerinoides ruber, to further explore the paleoclimatic signals recorded in Sunda Shelf sediments during the mid-to-late Holocene.