Climate-ocean coupling off North-West Africa during the Lower Albian:: The Oceanic Anoxic Event 1b

High-resolution records of organic and inorganic geochemical proxies document environmental changes during Oceanic Anoxic Event 1b for the Albian upwelling system at DSDP Site 545 Mazagan Plateau off NW Africa. Sea surface temperature estimates based on TEX86 analyses show an abrupt rise by similar to 3 degrees C concurrent with a more than 2-fold increase in accumulation rates for organic carbon and siliciclastic sediment components. Geochemical grain-size indicators (Si/Al and Zr/Al) indicate the influx of overall finer grained sediment during the event. Our data suggest that the warming phase associated with OAE 1b resulted in an attenuation of the NE trade wind system and a weakening of local upwelling conditions. Higher amounts of precipitation over NW Africa and an associated higher continental run off may have supplied nutrients to the eastern North Atlantic and fostered the production of organic matter and black shale deposition. (C) 2008 Elsevier B.V. All rights reserved.