The Study Of Baitutang Ophilotic In East Part Of South Tianshan

Baitutang ophiolitic melange is located in the north of south Tianshan, belong toYushugou-Tonghuanshan-Liuhuangshan ophiolite belt. This dissertation is object on thecharacter of ophiolitic of rock combination、metamorphism、deformation、petrology、petrochemistry、geochemistry, discuss the tectonic setting and emplacement mechanisms ofBaitutang ophiolite, then combined with regional tectonic evolution to analysis the Baitutangophiolite tectonic significance.Baitutang ophiolitic melange is fault contact relationship with Devonian,the chaoticmatrixes is basalt, and it composed of different tecnotic blocks such as serpentinite、culumate、gabbro、plagiogranite、siliceousrock and so on, every slice are contract with tectonism. Thescale of dike swam which stand for spreading mechanism are small and siliceousrock、basicvolcanic rock are more developmental.The rock are common metamorphism and disformation,basalt are intensively uralitization and mylonitizaion. Altuough successionof strata isdemolished by the late tectonic, the combination of ophiolitic are intergrated.The metaperidotites of Baitutang ophiolitic melange show low SiO2、Al2O3、TiO2、CaO、K2O、Na2O,high MgO,and have low∑REE,the rare earth element distribution patternsappears “U”, they are depletion pyrolite from primitive mantle which had undergone partmelting. basic volcanic rock show high MgO, low K2O、Na2O and ω（Na2O）＞ω（K2O）,according to the characteristics of rare earth element and trace element, the basic volcanicrock can be divided three classes, the first two classes derived from depleted mantle which issimilar to nomal mid-ocean basalt; the late category have characteristic of N-MORB andE-MORB. The basic rock is very complex, which is produced in Mid-Ocean Ridge envirmentand subduction, the later are gabbro and some slice basalt. South tianshan ocean basin is alimited ocean basin by the analysis of the geochemical characteristics of MORB.The tectonic melange belt is formed in the late early carboniferous to middle latecarboniferous, because there is a lot of late carboniferous to the early Permian of granitewhich is cut off the tectonic melange belt.The emplacement mechanism of Baitutangophiolote are subduction-exhumation and subduction scraping collage,because there are twostages metamorphism and high pressure metamorphic mineral glaucophanes in the basic rocks.Comprehensive research show that the southern tianshan ocean opened in the middle-lateOrdovician, closed in late middle-Devonian, evolutionary phase of residual basin is from lateDevonian to early Carboniferous, evolutionary phase of continent collision is in lateCarboniferous.