BIOGEOCHEMICAL STUDY OF LOWER SARMATIAN BIVALVES FROM THE SOUTHERN MARGIN OF THE UKRAINIAN SHIELD AND THEIR STRATIGRAPHIC SIGNIFICANCE

Abstract

A possibility of using biogeochemical data to define synchronous stratigraphic levels in Sarmatian sections of southern Ukraine is considered. Data on chemical composition of bivalve Donax dentiger Eichw., Ervilia dissita Eichw., Obsoletiforma obsoleta (Eichw.), and Venerupis vitaliana (Orb.) shells from three known lower Sarmatian sections of the Ukrainian Shield southern margin are presented. In these sections, intervals with unusual distributions of some chemical elements (Na, Sr, Mn, B, and others) in molluscan shells are established. The data obtained suggest that hydrochemistry in the early Sarmatian brackish-water basin that covered the margin of the East European platform was influenced by collision-related tectonic movements in the Mediterranean mobile belt. The following consequences of tectonic events are inferred from biogeochemical data: (1) isolation and desalination of the Sarmatian basin; (2) activation of fractures in the southeastern margin of the Ukrainian Shield; (3) probability of mud volcanism. The established biogeochemical events are contrasting, steady, and thus can be used to define synchronous stratigraphic levels and to correlate Sarmatian sections.