Tianshan And Its Adjacent Areas Geological Evolution Of Continental Rift Volcanism In The Process

Tianshan orogenic belt is a part of mid Asia mega orogenic belt that located within China boundaries. It's basic tectonic trellis is result of lots of plates' combination, accretion, diving and collision orogeny during the process of pal-Asian ocean's formation, evolution and dying out which among northern Siberia plate, southern Tarim plate and China-Korea plate. During the process of Tianshan orogen formation twice large scaled continental-rift volcanism had been occurred, one is early Neoproterozoic-Precambrian volcanism, which caused by the spliting of Rodinia supercontinent, it is also the sign of the Paleozoic ocean basin's opening; the other is Carboniferous-Permian volcanism, During this period, Tianshan and its adjacent regions experienced fierce large scaled magmatic activity which formed Carboniferous-Permian large igneous province, and accompanied by cosmically mineralization at the later Paleozoic. After this, Tianshan orogenic belt entered the real inter-continental evolution phase. a good many mico-landblock of the early Neoproterozoic-Cambrian volcanic rock that distribute in the Tianshan orogenic belt and on its both sides, and the Carboniferous-Permian volcanic rocks that widely distribute in the Tianshan and adjacent regions are selected for subject investigating in this paper. Renewing the ocean-land format and ocean-land conversion process of Tianshan orogenic belt in the Paleozoic is the masterstroke for this paper. On the basis of detailed field investigation, many subjects, such asregional lithology,geochemistry,structural geology,volcanic sedimentology geology,sotope geochronology and synthesis analysis study of geophysics data, are adopted as instrumentality in the paper, this study lays emphasis on the formation, evolution and dynamics of early Neoproterozoic-Cambrian and Carboniferous-Permian volcanic rock in the Tianshan and its adjacent regions to find out Carboniferous-Permian volcanic rock property, eruptive sequence, time and space distribution characteristics, to resume and reconstruct evolution process of Carboniferous-Permian volcanic rock, and to explore connection of magmatism process and lithosphere stretching action of neopaleozoic ocean-land transformation in the Tianshan region. The fallowings are the main achivement:(1) Establishing tectonic-magma evolution trellis of Tianshan orogenic belt in the Paleozoic.(2) Puting forward that continental rift volcanic activity from Mid-late Neoproterozoic (Nanhua-Sinian) to the early stage of early Cambrian is the auspice of the opening of the Paleo-Asian Ocean.(3) Research indicates that volcanic rock system of Carboniferous-early Permian largely distributing in Tianshan and its adjacent region is contiental-rift volcanic rock system. Together with contemporaneous basic-ultrabasic intrusives and granite, they constitute a large igneous province, Tianshan (Mid-Asian) large igneous province.(4) Research puts forward that Bayingou ophiolite is the geologic record of Tianshan early Carboniferous "Red Sea Type" Ocean basin..(5) Research finds out that Carboniferous-Early Permian volcanic rocks system that largely distributing in Tianshan and its adjacent regions are continental rift volcanic rock system, it originated from mantle plume, they may be the surface response of the deep Geodynamics of paleo-Tethys extension effect in central Asian region.