Late-Quaternary biogenic productivity and organic carbon deposition in the eastern Arabian Sea

Paleoproductivity variations in the eastern Arabian Sea, during the late Quaternary period (∼42 ka BP to present), have been studied using accumulation rates of sedimentary biogenic components: organic carbon (Corg), nitrogen (N), CaCO3, Sr and Ba. Such a multi-proxy approach reveals decreased surface productivity during the last glacial–interglacial transition. The observed change of surface water productivity during the last glacial–interglacial period is in antiphase to those observed in other low- and mid-latitude upwelling areas, however, consistent with some of the upwelling regions like NW Africa and NW Mexico. Sedimentary Corg and N are found to be decoupled from surface productivity trend, with significant enrichments in Corg and N during the Last Glacial Maximum (LGM). This is interpreted in terms of increase in sedimentation rates (by a factor of 3–4) resulting in the better preservation of Corg during the LGM.