STRATIGRAPHIC AND GEOGRAPHIC DISTRIBUTION OF LATE EOCENE FORAMINIFERS IN THE NORTHERN PERIPHERY OF THE TETHYS

Abstract

Foraminiferal assemblages from the Belaya Glina basin, which extended from the Black Sea to the Aral-Turgai region and eastern Central Asia, and from the inner seas of Transcaucasia are analyzed. The assemblages mainly consist of species migrated from the Mediterranean after the fauna extinction at the pre-Priabonian time. The most representative assemblages are established in the Crimean-North Caucasian region, where the Planulina costata Zone subdivided into the Brotzenella taurica and Bolivina antegressa subzones is distinguished on the basis of benthic foraminifers as overlain by the Almaena taurica or Nonion curviseptum beds. The climate- and facies-dependent variability of fauna is detected to the north and east of the region, but the guide species of the P. costata Zone were found everywhere. These species are used to correlate the local biostratigraphic subdivisions to each other and with the units of the standard stratigraphic scale. Changes in the foraminiferal assemblages from the Priabonian boundary beds of different-facies sections are considered. The Belaya Glina basin corresponded to the northern province of the Mediterranean paleobiogeographic realm, where the Tajik and East Transcaucasia subprovinces are recognized.