DISCUSSION OF OPENING-CLOSING TECTONIC BELT OF PALEOZOIC IN SOUTH TIANSHAN MOUNTAINS, CHINA

The southern Tianshan mountains are located between the Tarim basin and the Central Tianshan Crystalline Belt of in China. Development of Paleozoic opening-closing tectonic belt consists of two stages. At the earliest stage, it belonged to retroarc basin of the Early Paleozoic. Secondary stage, limited oceanic basin was formed along with back-arc spreading, and extended into the South Tianshan Oceanic Basin between Kazakhstan and kirghzstan. Further west, development of oceanic basin was earlier in Kirghzstan than in china and ophiolite of Ordovician outcroped widely. At the early Silurian, retroarc basin was spread gradually change to oceanic basin. And almost at the same time, the South Tianshan Oceanic Basin subdued towards north along south marginal Tectonic Belt of the Central Tianshan and it was closed in end of the early Devonian. The South Tianshan range formed epicontinental sea in the Middle Devonian, and in end of the Carboniferous orogen was formed under the strong compression. According to tectonic features of various stage, opening-closing tectonic belt consists of 11 units in the South Tianshan range.