Mid Cretaceous (Cenomanian - Turonian) black shales from ODP Leg 207 (western Central Atlantic) : Palaeoceangraphy deciphered by calcareous nannofossils

点击翻译按钮获取中文摘要

Five sites (1257,1258,1259,1260,1261) of ODP Leg 207 recovered a good record of Mid to Late Cretaceous (Late Albian - Santonian) Black shales. These TOC-rich sediments, globally well known from the Cenomanian/Turonian boundary interval, are less common in the Turonian - Santonian interval. This latter period is rather characterized by hemipelagic -pelagic marls and limestones. The Turonian - Santonian black shales presumably reflect a regional control. Calcareous nannofossils are useful biostratigraphic markers enabling a biozonation on a high resolution scale. They are furtheron a powerful tool for deciphering past palaeoecological proxy data for reconstructing nutrient fluxes, thus allowing the recognition of fertility changes. We therefore plan to analyse the calcareous nannofossils of the Late Albian - turonian black shales from three sites (1258,1260,1261) with the following objectives: to devolop a high resolution biostratigraphic framework, to understand the palaeobiogeography of equatorial nannofossils and their climatic implications, to view and interprete the black shale formation in the light of calcareous nannofossils productivity, to decipher the depositional enviroment of global and regional black shales.