The echinoids of the K/T boundary Moravitsa section (Western Fore-Balkan, Bulgaria)

The Moravitsa section is located SSE of the homonymous village, SW of the town of Mezdra (Vratsa District, southern part of north-west Bulgaria), near an affluent of the Iskar river. It is part of the southern limb of the Mezdra syncline (West Fore-Balkan) that comprises, from base to top, the following Upper Cretaceous lithostratigraphic units: Dârmanci (=Darmantsi) Formation, Kunino Formation, Mezdra Formation, and Kajlâka Formation (Jolkičev, 1986; 2006). The section is mostly represented by sandstones (Darmantsi Formationpassing into glauconitic nodular limestones (Kunino Formation) in the lower part, and a thick cyclic carbonate sequence including chert levels and thin-bedded limestones with abundant chert concretions (Mezdra Formation), some of them echinoids themselves, in its upper part. It keeps a register of the K/T boundary, based on an iridium anomaly (Sinnyovski, 1998, 2003). This fact has favoured the study of the occurring micro- and macrofauna, especially in the last decades (e.g. Stoykova et al., 2001). In the last two years, the current authors have developed an integrated biostratigraphic framework based on its ammonites, inoceramids and echinoids that will soon be submitted. This is an advance of its echinoids chapter. Keywords: Echinoidea, Maastrichtian, Danian, Moravitsa, W Fore-Balka