Current ideas of Eastern Ustyurt tectonic inhomogeneity in the context of petroleum potential of Palaeozoic deposits

The authors discuss the current ideas of Eastern Ustyurt tectonic inhomogeneity in the context of petroleum potential of Palaeozoic deposits. Structural surface of the crystalline basement within the Ustyurt region has a complicated, often mosaic pattern. The highest structural position of the basement is typical of the Baiterek-Terengkuduksky and Kassarminsky swells, as well as the Monchoklinsky uplift and south-western part of the Kuanysh-Koskalinsky swell. Taking into account the features of the current structure of the Permian-Triassic (Р2-Т1) sequences, the Eastern Ustyurt territory can be divided into three major tectonic members, they are: North Ustyurt syneclise, Central Ustyurt zone of uplifts, and South Ustyurt syneclise. The latter neighbours the Tuakyr-Kaplankyrsky zone of uplifts. What is more, the eastern and north-eastern shoulders make the flexure zone that bounds it along all the length from the western slope of the Arka-Kungrad uplift to the southern slope of the Aktumsuksky uplift. Comparative analysis of paleotectonic evolution of the Eastern Ustyurt and its current structural and tectonic model brought the authors to the following conclusions. History of the platform cover formation consists of two stages: Mesozoic-Paleogene and Neogene-Quaternary, which are separated by the stage of elevation, denudation, and hiatus. Carrying out the analysis of Mesozoic-Cenozoic sedimentary cover formation history, one should take into account the influence of Palaeozoic basement structure, overall progress of Mesozoic-Paleogene movements and, finally, the particular role of neotectonic deformations. Consequently, a definite relationship is determined between the Palaeozoic basement and architecture of the Mesozoic-Cenozoic sedimentary cover. Special importance is attributed to faults. Presence of high-amplitude faults with steep flanks of folds, which originated from neotectonic processes is typical of the elongated swells. Some researchers underestimate the significance of neotectonic processes and their influence on the ultimate formation of regional architecture of sedimentary cover and local structures within it. It becomes apparent that presence of deep troughs below anticline traps developed in Mesozoic-Cenozoic time is a positive factor for formation of hydrocarbon accumulations