Problems of origin and evolution of Pre-Caspian depression
Problems of structure and evolution history of Pre-Caspian depression, origin of which is explained differently by many researchers are considered and analyzed in the article. Difference in views on these problems lies in interpretation of three principal issues: basement age; stratigraphic volume and formational composition of sedimentary cover; genesis of markedly defined linear structures of Scythian-Turan plate. From seismostratigraphic generalizations of recent geological and geophysical data there were revealed structural peculiarities of Central - Pre-Caspian depression boundary faults, stratigraphic position of key reflection horizon P3 - a bottom of Devonian deposits was detailed and proven; structural maps of the main horizons of sedimentary cover were compiled. The authors propose a model of successive geological events within the territory of Pre-Caspian depression - from Early - Middle Riphean and up to Early Permian - stage of origination and formation of Kungurian salt-bearing basin. Pre-Caspian depression outlined within limits of salt-domed area is considered in a series of geological bodies of the Earth's crust relating to category of oil and gas provinces or oil and gas megabasins and was formed by the end of Kungurian time following thick salt-bearing strata accumulation served as regional cap and creating an unity of fluid-thermal system of the province.