Sr, Nd isotopic evidence of terrigenous flux variations in the Bay of Bengal: Implications of monsoons during the last ∼34,000 years

Abstract

Sr and Nd isotopic compositions of a sediment core from the Bay of Bengal are used to constrain the provenance and transport pathways of their terrigenous component during the ∼3 to 34 14C kyr BP. The results clearly demonstrate a distinctly different source for detrital fluxes on the Ninetyeast Ridge from that of distal and western Fan sediments. There is a systematic pattern of climate-related variability in 87Sr/86Sr and ε Nd(o) values at the studied location. Pulses of low 87Sr/86Sr, higher radiogenic Nd and high silt content occurring at ∼5-7 kyr intervals suggest significant changes in the detrital source. Increased supply of Irrawaddy-derived sediments appears to be the dominant source for these pulses. Our results support the hypothesis that rapid cold events of North Atlantic (Heinrich events) are characterized by the intensified northeast monsoon. Copyright 2005 by the American Geophysical Union.