Cretaceous/Tertiary boundary sections in the east Balkan area, Bulgaria

Cretaceous/Tertiary boundary sections in Bulgaria on the coast of the Black Sea near Bjala, 35 km south of Varna have been identified by micro- and nannofossils, magnetic reversals and event markers. The hemipelagic sediments of profile Bjala 2b and Bjala 2c show an iridium enrichment in the boundary clay, a minimum of CaCO3, shocked quartzes, a mass extinction of Cretaceous nannoplankton species, as well as a bloom of survivors at the K/T boundary and the first appearance of new nannoplankton species after the K/T event. The comparison of biostratigraphic and magnetostratigraphic results provides a time scale for the evolution of these new nannoplankton species. -from Authors