GEOLOGICAL STRUCTURE OF THE BASEMENT OF THE CENTRAL PART OF THE WEST SIBERIAN PLATFORM (Yugansk-Koltogorsky region). Ivanov, N.P. Kostrov, N.V. Vakhrusheva, Yu.V. Erokhin, S.V. Berzin, O.E. Pogromskaya, A.E. Stepanov


Petrography, petrochemistry, geochemistry, geochronology and biostratigraphy of rocks of the complexes of the Pre-Jurassic base of the Yugansk-Koltogorsky zone of the central part of Western Siberia were studied using the core of more than 40 wells. A geological map of the pre-Jurassic foundation of the 1:500000 scale zone has been constructed. At the base of the stratified strata of the region are metamorphic formations – quartz-sericite, albite-chlorite-quartz and other shales of the green shale facies, mainly its lower ones. The middle Paleozoic undifferentiated is represented by a terrigenous-carbonate stratum with subordinate interlayers of effusions of the main composition. The Middle-Upper Devonian consists of limestones, dolomites with subordinate bundles of sandstones and clay shales, with a thickness of more than 400 m. Volcanogenic Upper Devonian is mainly represented by island-arc andesites, basalts and their tuffs. Sedimentary deposits of the Upper Devonian – Lower Carboniferous are represented by clay and siliceous shales, sandstones, gravelites and conglomerates with a thickness of at least 500 m. Permian–Lower Triassic volcanites perform large rift zones dividing Paleozoic rock complexes into separate tectonic blocks. Their Ar-Ar age is 268.4±7.5 million years, i.e. volcanism in the axial rift zones of Western Siberia began earlier than thought.

Four main fault systems have been identified: the earliest north-northwest strike; a younger submeridional discharge system controlling the development of Permian-Triassic rifts; then - a system of faults of the northwest to sublatitudinal direction and the fourth system of the northeast strike.

Computer density modeling of the deep structure was performed at large polygons in the center of the Yugan zone and in the north of the Koltogorsky zone.

The book is of interest to specialists in the field of geology and geophysics.