Changes in paleoenvironments in the Atlantic Ocean during Cretaceous times: results from black shales studies

Abstract

Large parts of the Cretaceous Atlantic Ocean are characterized by the wide-spread deposition of organic-carbon-rich sediments (»black shales«), with a maximum occurrence during Aptian/Albian and Cenomanian/Turonian times. In order to explain the origin of these black shales, changes in the amount and type of organic matter in relation to changes in paleogeography, paleoceanic circulation, and paleoclimate have been investigated in detail. The study is mainly based on calculation of accumulation rates of marine and terrigenous organic carbon, organic carbon/sedimentation rate relationships, and estimates of paleoproductivity.