ASSESSMENT OF THE COAL RESOURCES OF THE KYRGYZ REPUBLIC:

COAL CHARACTER AND DISTRIBUTION, GEOLOGY, MINING, AND IMPORTANCE TO THE NATION'S FUTURE

USGS Open File Report 97-137A (English)

A. GEOLOGIC SETTING

Coal in Kyrgyzstan is of Jurassic age. The coal is younger than the main bituminous coals of Europe, eastern North America, South America, Australia and India. The Kyrgyz coals are, however, older than the low rank coals of western North America. Significant coals of about the same age as those in Kyrgyzstan are present in other Central Asia countries, China, and Russia.

In central Asia the rocks of Jurassic age are overlain unconformably by a variety of rock types ranging from marine Late Cretaceous sedimentary rocks to non-marine thick wedges of fan-type coarse clastics shed by the uplifted mountains being formed during the ongoing Alpine Orogeny. The net effect of Late Cretaceous, Tertiary, and Quaternary geologic history has been concealment of the Jurassic coal-bearing rocks, though exhumation by recent erosion is presently occurring.

Kyrgyzstan and adjoining parts of Central Asia have a very complex geologic history, and much of that history is preserved in the rocks comprising the country. Bakirov and Burtman (1984) recognize four megastages in the geological history of the area. Each megastage is either geosynclinal- orogenic or platform-orogenic in character. From the standpoint of coal geology, only the history of the last megastage, the Mesozoic-Cenozoic platform-orogenic megastage, directly affects the presence and distribution of coal-bearing rocks in the country.

The coal-bearing rocks of Kyrgyzstan are of continental origin and were deposited north of the Tethyan Sea that formerly occupied a large area in central and southern Asia. At least four transgressive-regressive cycles of the seas occurred between Late Triassic age and Late Jurassic age in southwestern and southern Asia (Poliansky, 1980). As much as 6,000 meters of Late Triassic and Jurassic rocks of both continental and marine origin were deposited in localized sedimentary basins on the periphery of the Tethyan Sea. The Jurassic rocks that are preserved in Kyrgyzstan were possibly deposited during the middle two of the above-mentioned cycles. Most occurrences of the Jurassic rocks in the country seem to be tectonically separated remnants of formerly more extensive bodies of Jurassic rocks (fig.4).

The Jurassic rocks of the Uzgen Basin are one of the largest occurrences of Jurassic sedimentary rocks exposed in central Asia. Solpuyev and Bakirov (oral communication, 1994) state that the Jurassic rocks are thinner and mostly of continental origin in the northern part of the Basin where coals occur, and are increasingly thicker and more marine in origin in the southern part of the Basin. Faulting, folding and erosion, all mostly related to the latest cycle of mountain building, the Alpine Orogeny, have locally displaced or removed segments of the Jurassic rocks in the Basin. The rank, type, and quality of the coals in the Basin reflect their depositional history and subsequent geologic events in the area.

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