Sr-Nd isotope composition of the Bay of Bengal sediments: Impact of climate on erosion in the Himalaya

Abstract

A temporal high-resolution analysis of Sr-Nd isotopic composition, Fe, Al and V concentration and magnetic susceptibility (MS) has been carried out in a sediment core from the western Bay of Bengal to trace sediment sources. Significant variations in the Sr and Nd isotopic composition and corresponding MS and elemental Fe/Al and V/Al ratios are observed in the sediment core with depth (time) indicating variable contributions from sources. The observed changes in the sediment provenance correlate well with the climatic record of the region, highlighting the important influence of climate over erosion. Relatively lower 87Sr/86Sr and higher εNd corresponding to the Last Glacial Maximum (LGM) suggests proportionally reduced sediment contribution from the Himalaya. Erosion rate over the Himalaya decreased during LGM due to combined influence of reduced intensity of the southwest monsoon and larger extent of glaciations over the Higher Himalaya, the main source of sediments to the Bay of Bengal. Copyright © 2011 by The Geochemical Society of Japan.