Home – Home – Jornals – Russian Geology and Geophysics 2003 number 8

The Oceanic Anoxic Event that occurred at the transition from Cenomanian to Turonian (OAE2) is a bright episode in the Cretaceous history. The section of the Cenomanian-Turonian terrigene deposits on the Nizhnyaya Agapa River (Ust'-Yenisei region) with vestiges of OAE2 has been analyzed in sedimentology and palynology. Textural features of deposits as well as their facies interactions in the section have been studied in detail. Stagnation and normal-marine settings alternate, which is typical of black-shale facies. This is well expressed in the replacement of shallow-marine sand rocks containing benthic fauna by black and brownish-gray leaf clays with signs of pyritization, without macrofauna, reflecting settings of stagnation. Qualitative and quantitative changes in the composition of organic-wall microphytoplankton have been established, and the facies-dependent dynamics of taxonomic variety of dinocysts has been traced. Comparative analysis of distribution of palynomorphs has been performed in deposits related to the Cenomanian-Turonian Oceanic Anoxic Event in different regions.