Study of the Paleozoic Base of the Terek-Caspian Trough Based on the Complex of Geological and Geophysical Data

Abstract

The article presents the primary results of paleotectonic studies that were conducted in order to study the deep structure of the Paleozoic basement, to reveal the patterns of development of the faulty-block tectonics of the Terek-Caspian trough, kinematic features of tectonic movements, and their contribution to the formation of the modern structural plan of the region. During the course of the work, the analysis of the capacities and facies of all carbon units was carried out on the basis of the summary of the available drilling data, seismic and other geophysical materials. As a result of the studies based on the analysis of geological, geomorphological and individual geophysical methods, the structural-formational profiles, the sedimentation rate graphs and the thickness map of the Cretaceous sediments of the sedimentary cover were made, and the elements of the deep structure, spatial position and activity time of separate interblock zones -faults were revealed. The article presents the data concerning the history of the formation and the degree of activity of separate faults on the territory of the Terek -Caspian trough. During the pre-Jurassic period, the investigated territory had already possessed a whole system of blocks bounded by faults, and the subsequent significant changes in the structure of the Upper Cretaceous structural plan were determined as a result of the intense manifestation of ascending movements. The formation of structural -tectonic elements in the areas of the intensification of the vertical movements of the blocks of the basement along the faults during the general rise of the territory led to the bending of the Upper Cretaceous bedrocks. At the same time, each unit developed independently. It is reflected in the composition of rocks and their thickness. The movements of the Mesozoic blocks of rocks in the early formed fractures caused a further complication of the structural-tectonic plan of the Upper Cretaceous sediments, which was reflected in an increase in the slope of the wings, their fragmentation by systems of disturbances, and the increase in tectonic fracturing. It is necessary to note that the intensity of the tectonic activity of separate faults at various stages is differentiated, in some cases, at certain stages of time there was a change in the sign of movements. In general, the region was subject to long-term general meridional compression processes with the formation of linear structures as well as processes associated with the reorientation of block compression and right-shift processes. It is proved by the nature of the link junction of folded structures within the investigated region.