Conchyliofauna of Khazar Complexes of the Dagestan Coast of the Caspian Sea

Abstract

The study of the biocomplexes of the Khazar horizons of the Dagestan coast of the Caspian Sea and the identification of faunal criteria for recreating the habitat conditions of paleobassins, which allows for more reliable reconstructions of individual stages of the Late Eopleistocene. Biostratigraphic and morphometric research methods were used to study the Khazar sediments and the mollusks contained in them. Various didacn complexes allow us to stratify the sediments containing them in detail. Changes in the composition of fauna in the section of marine sediments are mainly associated with environmental conditions and the nature of sedimentation, which allows us to indirectly use the change of different facies complexes as a periodization of sediments. The biostratigraphy of the Caspian Late Eopleistocene is based on evolutionary changes and patterns of ecological change in the communities of mollusks of the genus Didacna Eichwald in space and time. The study of the conchylofauna of the Khazar horizons of the Dagestan region of the Caspian Sea showed that two groups of crassa and trigonoides mollusks are mainly represented in the complexes, and the leading and characteristic species are identified. The analysis of the distribution of the main groups of didacnas by section, the stability of their composition and intergroup differences indicates a high reliability of the division of the Caspian sediments on this basis.