Paleozoic collisional belt of the South Tien Shan: A review

Abstract

The South Tien Shan was formed by the late Paleozoic (Hercynian) collision between the Precambrian continents of Karakum and Tarim in the south and the early Paleozoic Kazakhstan continent in the north. The most eye-catching geological features of the South Tien Shan include various Silurian to Carboniferous marine sedimentary formations, which are tectonically juxtaposed with fragments of ophiolites; suprasubduction and intraplate volcanics and crosscut by Carboniferous to Permian orogenic granitoids. Major tectonic cycles can be traced through the entire South Tien Shan belt over 2000 km from west to east. The Late Proterozoic accretionary events at the active margins of Rodinia were followed by continental rifting in the early Paleozoic. The opening of new oceanic basins known as the Turkestan Ocean took place from the late Ordovician to early or middle Devonian and was accompanied by active subduction in island arcs and active continental margins. Input of materials from eroded island arcs into sedimentary basins is registered in lower-middle Paleozoic and younger sediments. Devonian intraplate magmatism made another significant contribution to the formation of continental crust of South Tien Shan. Precambrian microcontinents that existed within the Turkestan Ocean during the early Paleozoic as separate blocks were later accreted to continental margins together with island-arcs and made up a basement, on which the Middle Paleozoic carbonate platforms were formed. The last episode of suprasubduction magmatism, which started in the Lower Carboniferous (Visean) and reached its peak in Serpukhovian - Bashkirian, was followed by collision and final closure of the Turkestan Ocean in early Permian.