SEARCHING FOR OAE2 IN COASTAL TANZANIA: CENOMANIAN-TURONIAN FORAMINIFERAL BIOSTRATIGRAPHIC AND CHEMOSTRATIGRAPHIC RESULTS FROM THE CRETACEOUS TANZANIA DRILLING PROJECT

Nine boreholes drilled during the Cretaceous Tanzania Drilling Program (TDP) have yielded a nearly complete composite marine sediment record spanning from the lower Turonian through lower Campanian. Because of the clay-dominated lithologies and shallow burial depth, microfossil preservation is extraordinarily good through most of the drilled sequences, providing good age control and valuable insight to the climate and oceanography of the western subtropical Indian Ocean region. Multiple attempts to recover a continuous Cenomanian-Turonian boundary interval failed because of the presence of a loose sand bed that collapsed when drilled, causing the drill bit to get stuck and abandonment of the borehole. Absence of microfossils from the sand unit prevents its age determination, and no cores from the uppermost Cenomanian have thus far been obtained. Despite recovery of an unusually thick (75 m) sequence assigned to the planktonic foraminiferal Whiteinella archaeocretacea Zone, which has been estimated to span 0.54 m.y. according to the 2004 geologic time scale, bulk carbonate and organic carbon δ¹³C analyses do not show a shift that can be associated with Oceanic Anoxic Event 2 (OAE2). New data from single species oxygen and carbon isotopic analysis, with selection of two planktic and two benthic species per sample, detailed taxonomic analysis, planktic species abundance counts, and planktic:benthic ratios will be obtained to evaluate how much, if any, of the OAE2 interval was recovered during the Cretaceous TDP campaign.