Fold-thrust dislocations in Triassic sediments The Scythian-Turanian platform

Abstract

Relevance. The main prospects for the discovery of new accumulations of hydrocarbons are associated with the Triassic deposits of the Scythian-Turanian platform. Despite the long history of research, many issues of the geological structure of this complex remain insufficiently developed. One of them is the structure of anticline structures – the main search facilities for oil and gas. Until now, the prevailing point of view is about the decisive role of vertical tectonic movements in their formation. At the same time, in recent years there has been more and more evidence of the presence of dislocations in the Triassic section formed under the influence of lateral compression forces. One of these areas is the Zhetybai-Uzen stage of the South Mangyshlak trough. Studying the structural features of the folds and ruptures developed here will solve the problem of the mechanism of their formation and reveal the genesis of intraplate dislocations. Aim. To study the morphology of folded and discontinuous disturbances of the northern side of the Yuzhno-Mangyshlak trough in order to determine their morphology and conditions of formation. Methods. Comprehensive analysis of geological and geophysical information, including materials of seismic exploration, deep drilling. Macro- and micro-description of well cores has been performed. Lithological and stratigraphic dissection and correlation of well sections were performed using data from all types of logging, paleontological definitions of organic residues. The materials of the seismic survey of MOGT with a high frequency of observations were used. Methods of seismostratigraphy and structural analysis are applied. Results. The conducted studies indicate the determining role of tangential compression in the formation of the structure of Triassic sediments. The morphology of specific fold-thrust dislocations, as well as layer-by-layer disruptions, is described. The obtained results can contribute to the solution of a number of issues of petroleum geology, the choice of rational methods of geological exploration. The research materials can be used in the study of the geological structure of other less studied areas of the young platform.