In Early Permian time the North Caspian depression became separated from the open ocean to form an enormous salt lake. Under an arid climate not less than 5 km of salt collected during a time span of 3.6 million years. The most subsided part of this depression was associated with a rift graben and was finally compensated by evaporites. See News Letter No. 38.
The Lower Permian evaporites of the north border of the North Caspian depression are divided from the bottom upward into three lithologic units: carbonate-sulfate, salt, and sulfate- clastic. The age of the lower is Artinskian-early Kungurian, and the upper two are Kungurian. Six rhythm members are recognized in the carbonate-sulfate unit, each beginning with dolomite and ending with anhydrite. Nine rhythm members are present in the salt, each beginning with dolomite-anhydrite or anhydrite and ending with halite or potassium-magnesium salts. Five stratigraphic salt members are recognized from the bottom upward as follows: Volgograd, Balykley, Lugov, Pogozh, and Antipov. These are separated from one another by anhydrite-dolomite or anhydrite marker beds.
On approaching the border step of the North Caspian depression from the north the thickness of the salt unit increases abruptly due to the appearance in the section of the Volgograd member. This Volgograd salt was deposited as a large lens in a paleo-depression that extended along the northern part of the North Caspian sedimentary basin.
The Volgograd and Lugov salt units are largely halite, and processes of plastic redistribution of this salt are widespread. This salt tectonoic activity is one of the factors causing the structural discordance between the sub-salt, intra-salt, and supra-salt horizons in the study area.
These last three paragraphs are taken from Nikitin, Pisarenko, and Alekseyev, 1986; digested in Petroleum Geology, Vol. 23, No. 9/10, three maps and three cross sections.
The Kama-Kinel system of downwarps are narrow, elongate troughs that extend along the eastern margin of the East European craton. This system is some 1000 km long, and individual downwarps are 20-90 km wide. On the north it extends into the Timan-Pechora oil-gas province. On the south it extends to the North Caspian depression, which I think is a continuation of the system. I would even like to designate this entire feature as the Kama-Kinel-Caspian system of downwarps. See News Letter No. 11. Some other News Letters dealing with the Caspian region are Numbers 75, 83, 99, 107, 123, 124, 144, and 145.
Copyright James Clarke 2003. You are encouraged to print
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