THE MEZINO-LAPSHINOVKA REFERENCE SECTION OF THE UPPER CRETACEOUS AND PROBLEMS OF SANTONIAN-CAMPANIAN BOUNDARY IN SARATOV AREA NEAR THE VOLGA RIVER

Abstract

Results of multidisciplinary study in the Upper Cretaceous reference section and characteristics of the Mezino-Lapshinovka Formation stratotype are presented. The late Santonian age of the formation is substantiated based on the analyzed organic remains. The formation is considered to be a stratigraphic equivalent of the Pteria Beds, the age of which was animatedly discussed during over a century. The age of the Mozhzhevelovyi Ovrag Formation that underlies the Mezino-Lapshinovka Formation and yields foraminifers, radiolarians, and calcareous nannoplankton is also discussed. The ammonite assemblage of the lower upper Campanian first discovered in the basal part of the Ardym Formation of the Volga region is characterized.