The Position of the Santonian-Campanian Boundary in the Alan-Kyr Section (Central Crimea): New Micropaleontological Data

This work presents the results of determination of foraminifers and nannoplankton from the Upper Cretaceous deposits of the Alan-Kyr section (the central part of the Crimean Mountains). The interpretation of these data, together with previously obtained palynological and paleomagnetic data, allow us to justify the age of country deposits. In the lower part of the section, beds with planktonic foraminifera are correlated with the Santonian part of the Dicarinella asymetrica Zone. The benthic foraminiferal assemblages also belong to the Santonian interval and allow us to subdivide this interval in more detail. Based on the nannoplankton data the transitional Zone CC17 was identified, which corresponds to the Upper Santonian–Lower Campanian. The base of a probable analogue of Chron C33r is distinguished within these deposits and is proposed for use as a primary feature to define the lower boundary of the Campanian.