Lithological and paleogeographic conditions for the formation and location of sedimentary basins of the Caspian region

The article discusses the lithological and paleogeographic conditions of the formation and location of sedimentary basins of the Caspian region.Its main feature of morphology and structure is the presence of superdeep depressions.Non-palinspastic lithological-paleogeographic reconstructions performed using classical methods of thickness and facies analysis, showed that in the Middle-Late Triassic and Early Jurassic continental conditions prevailed in most of the Caspian region with the accumulation of terrigenous, less often carbonate, and in some places volcanogenic sedimentary strata.In the Middle Jurassic, large areas of stable subsidence and inundation appeared, and in the Late Jurassic and Early Cretaceous, predominantly marine conditions were established in the region with a predominance of carbonate sedimentation in some zones.In the Late Cretaceous, the entire region was a clay-carbonate shelf, in places over-deepened.At the end of the Paleogene -Early Miocene, in the southern part of the region, the processes of arch formation and orogenesis intensified, which were accompanied by the draining of the zones of orogenesis and some areas of the Northern and Eastern Caspian Sea, and the formation of over-deepened shelf troughs ahead of the front of the zone of active orogenesis with the predominance of terrigenous sedimentation in them.Substantial drainage of the territory of the Middle and North Caspian took place in the Pliocene, when in the relict, relatively deep sea depressions of the South and Middle Caspian region south of 42º N lat.formed powerful delta complexes of Pliocene rivers flowing from the East European platform and, in part, from the Turan plate.The results of the reconstructions made it possible to restore the conditions and environments of sedimentation characteristic of the Caspian region in a long historical and geological retrospective and to obtain the necessary information for the subsequent numerical modeling of sedimentary basins and evolution of their hydrocarbon systems.