The geological structure of the Kazakhstan portion of the Caspian Sea shoreline is defined by two large
The Pre-Caspian depression or syncline, which is understood as a region of development of saline-dome tectonics, belongs to the East European platform and it is the part of the platform with the most
deeply submerged basement. Subsalt, saline and persaline complexes are distinguished in the sedimentary cover.
The Prekungurskiy (lower Permian) subsalt complex is predominantly made up by terrigenous formations with thick carbonate layers in the upper parts of the section. The thickness of this complex reaches 5 to 6 km.
The Kungurskiy saline complex is formed by a salt rock with anhydrite, dolomite, potash and terrigenous rock intercalations. Presently, the accumulation of sediments at the bottom of Caspian sea happens due to terrigenous (60%), biogenetic (30%) and chemo-genetic carbonate (10%) material.
The middle part of Caspian Sea is where major sediment accumulation takes place and the Northern part (shallow water shelf) is mainly the removal area.
In the South and South-East of the region the Precaspian depression borders along the large and deep fault with epigercious Turanskaya plate. Its foundation is a heterogeneous structure formed by geological formations with various composition and age – from Precambrian to Perm & Triassic periods inclusively.
On top of the foundation, having strong structural discrepancy, is a deposit of Mesozoic – Cenozoic cover of continental and sea clays, aleurites, sand and sandstone, limestone and marls with an average thickness of 4 to 5 km (the thickness doubles in some depressions).
Oil and gas contents in the region are consistent with its tectonic elements and hydrocarbon system. The most significant fields are confined to subsalt deposits and located at depths exceeding >2000 m.
The oil fields of Turanskaya plate of Mangyshlak oil and gas-bearing province located at the depth of less than 500 m.