Past productivity variations and Organic Carbon burial in the Gulf of Aden since the last glacial maximum

Abstract

We reconstructed the evolution of marine primary productivity across the last déglaciation in the Gulf of Aden based on micropaleontological and sedimentological data from marine core MD92-1002. Dinoflagellate cysts analysis suggests that the glacial period was characterized by weakened upwellings and well ventilated bottom water. Primary productivity increased from 14.5 ka with a maximum between 12.6 and 10.8 ka, then declined during the Holocene. Maximum of primary productivity in the Gulf of Aden took place about 3 ka earlier than the maximum of upwelling intensity off the Oman margin, and was not phase-locked with the maximum of boreal summer insolation. XRF-derived bromine contents mimic the variations of Total Organic Carbon (TOC) in core MD92-1002. Both records show a strong glacial/interglacial signal that is largely decoupled from our reconstruction of surface productivity, suggesting that total organic content in core MD92-1002 is mainly controlled by preservation at the sea floor.