Ural-Tien-Shan Folded Region

the western part of the Ural-Mongolian folded geosynclinal belt. The Ural-Tien-Shan folded region begins with the folded structures of the Urals and continues southward beneath the gently inclined Mesozoic and Cenozoic beds of the Turan Platform; then, turning east, the folded strata crop out in the isolated ranges of the Kyzylkum Desert and thereafter in the southern ranges of the Western and Eastern Tien-Shan. The region forms an arc of Precambrian and Paleozoic rock that was intensively deformed during the Hercy-nian folding of the Upper Paleozoic and Early Mesozoic.

The idea of a unified Ural-Tien-Shan folded region was first introduced by A. E. Fersman (1931) and A. D. Arkhangelskii (1941) and subsequently elaborated by V. G. Gar’kovets (1964) and S. S. Shul’ts (1972), all of whom sought to establish a direct correspondence between major tectonic elements of the Tien-Shan and the Urals. Publishing his conclusions in 1953, A. L. Ianshin asserted that the Tien-Shan and Ural structures belong to folded formations that differed in age and structure. According to Ianshin, the north-south trending structures of the Uralides are intersected at right angles by the east-west trending structures of the Tien-Shanides, which continue westward into Ciscaucasia. Ianshin also maintained that the Tien-Shanides are separated from the Uralides by a sublatitudinal zone of deep faults.

Geologists also hold different views on the internal structure of the Ural-Tien-Shan folded region. Some believe that there are numerous deep vertical faults extending many hundreds of kilometers in a north-south direction in the Urals and in an east-west direction in the Tien-Shan. According to others, the primary structural element of the region is large overthrust nappes, compressed into a complex system of folds and broken by major faults.