Lower Maastrichtian inoceramid bivalves from the Oslen Krivodol section (Western Fore-Balkan, Bulgaria)

Abstract

Inoceramid data were used to characterize the lower Maastrichtian strata in the Western Fore-Balkan (Bulgaria), based on the newly discovered Oslen Krivodol section. The upper part of the Kunino Formation yielded a well-defined inoceramid-bearing level. A number of characteristic taxa make up the inoceramid assemblage, including Cataceramus palliseri (Douglas, 1942), C. subcircularis (Meek, 1876), C. barabini (Morton, 1834), C. glendivensis Walaszczyk, Cobban and Harries, 2001 and Endocostea typica Whitfield, 1880. Additionally, Trochoceramus spp. and “Inoceramus” sp. were also found. It is, therefore, assumed that both the Endocostea typica Zone and an undetermined (probably lower) part of the Trochoceramus radiosus inoceramid Zone are present in the section. It is also assumed that there is a mixing of faunas due to low sedimentation rates and local submarine washout.