Late Quaternary Asian Monsoon variability as recorded in marine archives from the Northern Bay of Bengal and the Northern South China Sea

Abstract

This work is based on the use of marine sedimentary archives to reconstruct past summer monsoon variability in the Ganges-Brahmaputra-Meghna basin, at the northern rim of the Bay of Bengal, and the Pearl River basin-Taiwan region, at the northern rim of the South China Sea. The quantity and composition of sedimentary bulk organic matter and terrestrial biomarkers (plant wax n-alkanes) are investigated to detect changes in paleo-precipitation patterns, terrestrial vegetation composition, and nature of terrestrial and marine organic matter exported to the deep ocean during the Late Pleistocene and Holocene. In both regions summer monsoon circulation reached maximum strength during the Early Holocene and terrestrial vegetation composition was largely driven by changes of summer monsoon precipitation intensity. The export of terrigenous organic matter to the ocean was higher in periods of stronger summer monsoon precipitation and/or periods of lower eustatic sea level. Altogether, it is concluded that the evolution of summer monsoon circulation should be studied as a single phenomenon across South and Southeast Asia.