Orbital-Scale Paleoceanographic Response to the Indian Monsoon in the Laxmi Basin of the Eastern Arabian Sea

International Ocean Discovery Program Expedition 355 performed a 1109.4 m penetration drill at Site U1456 in the Laxmi Basin of the Eastern Arabian Sea. The uppermost section (~121 m thick) was analyzed for the paleoceanographic change in response to the orbital-scale Indian monsoon. Correlation of δ18O values of planktonic foraminifera (Globigerinoides ruber) to the LR04 stacks determined the age model (~1.2 Ma). The geochemical contents correspond to the sediment facies such that high TC contents correspond to the pelagic carbonates. High δ15N values of bulk sediments coincide with the interglacial periods when denitrification was intensified. 87Sr/86Sr ratios and eNd values of detrital particles are controlled by the sediment sources (i.e., river sediments) as well as depositional processes. Mixed layer depth traced by δ18O and δ13C values between G. ruber and G. sacculifer varied in response to the monsoon activity. The sediments in the Laxmi Basin of the Eastern Arabian Sea record the orbital-scale variation of the Indian monsoon during the Pleistocene.