Tadzhik Depression

an intermontane basin lying between the mountain structures of the Gissar-Alai, Pamirs, and Hindu Kush. During the Mesozoic, Paleogene, and Neogene the depression was an area of stable sediment accumulation.

The basement is composed of crystalline Precambrian rocks and of terrigenous-carbonate, volcanic-sedimentary, and intrusive rocks of the Paleozoic-early Triassic. The sedimentary cover is divided into two parts: a lower platform complex (Late Trias-sic-Paleogene) and an upper orogenic complex (Oligocene-Anthropogene). The lower complex includes multicolored continental, lagoon, and marine deposits (1.5–4 km thick) filling a platform trough; the upper complex consists of red molasse (from 3–4 km to 6–8 km).

During the Mesozoic and early Cenozoic the structural plan of the Tadzhik Depression, largely determined by the structure of the basement, essentially did not change. At the end of the Neogene and the beginning of the Anthropogene the consedimentary troughs and uplifts were dislocated, and there emerged the intricate system of folds and nappes of the Tadzhik virgation, expressed in the relief as mountain ridges. The Mesozoic-Cenozoic cover contains petroleum and gas horizons and deposits of natural gas, coal, combustible shale, rock salt, and building materials.