Evaporites are not common in the Paleozoic rocks of Central Asia. They are present, however, in the Devonian, Carboniferous, and Permian sections of the Tian-Shan and Pamirs. They are not known in other parts of the region. Their precipitation was on a background of protracted molasse deposition or during the course of accumulation of carbonates, clastics, and volcanics. Several Paleozoic evaporite complexes are known in the eastern part of the region.
Givetian-Frasnian sulfate-bearing molasse in the Chatkal downwarp consists of 200-800 m of gypsiferous sandstone, dolomite, gypsum, and anhydrite.
The Upper Devonian Famennian sulfate-bearing sub-complex of the carbonate complex of the Chatkal and Kavak fold zones is composed of 300-330 m of gypsum, gypsiferous limestone, and shale.
The Lower Carboniferous upper Tournaisian sulfate-bearing sub-complex of the carbonate complex of the Dzhamandavan fold zone is limestone that carries beds and lenses of gypsum, shale, and limestone conglomerate 100-1000 m thick.
The Lower Carboniferous middle Visean sulfate-bearing complex of the Kokiyrim and Dzhetymtau downwarps contains contains limestones with beds and lenses of gypsum. This is the Karakiin Formation, which is 700-800 m thick.
In the Sonkul and Balyktin epi-Caledonian downwarps is a Lower Carboniferous (upper Visean-lower Bashkirian) salt- bearing sub-complex of a carbonate-clastic complex. Here the upper Dungrumin Formation (upper Visean) is redbed sandstone and siltstone with beds of gypsum and salt 120-500 m thick. The Karachaulin Formation is siltstone and sandstone with beds of gypsum, salt, and limestone (Namurian) 80-800 m thick. Here the upper Aktaylyak Formation consists of alternating variegated shale, sandstone, and conglomerate. At the top are gypsum and anhydrite (lower Bashkirian). The Aktaylyak is 100-800 m thick.
A salt-bearing sub-complex of a molasse complex is present in the Tyup downwarp. It is late Namurian to early Bashkirian in age. Gypsonosnaya (Gypsum--bearing) Formation is comprised of dolomitized limestone, marl, gypsum, anhydrite, salt, sandstone, siltstone, and shale (upper Namurian) 200-500 m thick. The Tyup Formation is red and variegated conglomerate, arkosic sandstone, and shale with beds of limestone and gypsum. It is lower Bashkirian. and 0-350 m thick. The lower Bashkirian Chaarkuduk Formation is sandstone, clay, siltstone, marl, gypsum, and limestone 40-500 m thick.
The sulfate-bearing halogen complex of the Dzhamandavan and Kavak fold zones is Upper Carboniferous (Orenburg Stage). The upper part of the Kodzhagul Formation is polymict sandstone with beds of clayey and bitumenous limestone and gypsum. Thickness is up to 200 m.
The sulfate-bearing halogen sub-complex of the volcanic- sedimentary complex of the Chatkal-Kuramin fold zone is Early Permian in age. The lower part of the Shurabsay Formation consists of conglomerate, sandstone, lenses of limestone and gypsum, and shale 560 m thick. This is the Karachatyr Horizon. The salt-bearing halogen sub-complex of the carbonate- clastic complex of the Darvaza zone is 300-400 m thick and is Late Permian in age. The Shakarsev Formation is composed of clays and sandstones with beds of limestone, gypsum, and salt.
Taken from Luk'yanov, 1986; digested in Petroleum Geology,
Vol. 23, No. 7/8. Copyright 1003 James Clarke. You are
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