CARBONATE FORMATION OF THE UPPER TRIASSIC WEST OF THE SCYTHIAN PLATFORM AND THE NORTH CAUCASUS

Abstract

Relevance of the work. Despite the long history of studies of the Triassic deposits of the Western Ciscaucasia and the North Caucasus, the scheme of their lithological-stratigraphic division and the correlation of sections of different tectonic zones remains poorly developed. This is especially true for the Upper Triassic carbonate formation, which is of oil and gas exploration interest. In this regard, the aim of the work is a detailed lithological and stratigraphic study of Upper Triassic sediments, elucidation of their occurrence conditions, and determination of the areal distribution of carbonate strata. Research methods. Macro- and microscopic studies of the core material were performed. Biostrati-graphic analysis of the Upper Triassic sections was carried out. To dissect the section, a complex of geophysical methods of well research was used, including all types of logging. The results of the work and the scope of their application. A detailed lithological and stratigraphic study of a powerful section of the Triassic sediments of the Western Ciscaucasia and the North Caucasus allowed us to identify a Late-Norian carbonate formation (the Velikovechnenskaya formation), to identify the features of its structure, the lithofacial composition of the composing rocks, the conditions of occurrence, to make typical sections in various tectonic zones, and the subsequent correlation - to outline the areal distribution of the strata. The zone of probable development of reef structures is determined. Conclusions. The carbonate formation may be of practical interest in the search for minerals, but the area of its development is characterized by a low degree of geological and geophysical knowledge. To clarify the boundaries of its distribution, to clarify the features of the internal structure, it is necessary to conduct additional seismic studies. Exploratory seismic work on a sparse network of profiles is recommended in the western part of the Kopan syncline, as well as along the north-eastern slope of the Kanevsko-Berezansky shaft from Berezanskaya Square to the Adygeya salient.