Correlation of the zonal schemes in the Quaternary sediments of the Bulgarian Black Sea shelf according to molluscs and ostracods

Abstract

The Candona Ostracod Zone corresponds the Upper Chaudinian where the Dreissena rostriformis tschaudae Molluscan Zone is indicated. The Didacna crassa pontocaspia – Dreissena euxinica and Didacna crassa pontocaspia – Alba ovata Molluscan Concurrent-range-zones corresponding to the Cryptocyprideis bogatschovi Ostracod Zone are interpreted respectively in the Middle Pleistocene, Old Euxinian and Uzunlarian Stages. The section of the Upper Pleistocenian (Karangatian) molluscan zones has not been presented for analysis of the Ostracod sequences. The sequence of the molluscan and ostracod zones in the inner shelf has been broken by a barren zone which corresponds to the continental sediments, deposited in the Early New Euxinian. The Loxoconcha lepida Ostracod Zone corresponds to the following in superposition Upper Euxinian Dreissena polymorpha – Dreissena rostriformis distincta Molluscan Concurrent-rage-zone. The Hydrobia ventrosa – Monodacna caspia Molluscan Zone together with the following in superposition Mytilus galloprovincialis Zone comprise the sediments of the Old Chernomorian. The intervals occupied by the Cyprideis torosa Ostracod Zone correspond to these molluscan zones. The Falunia rubra – Loxoncha granulata Osatracod Zone comprises the area occupied by the Spisula subtruncata triangula Molluscan zone including also the upper parts of the Mytilus galloprovincialis Molluscan Zone.