南天山榆树沟—铜花山构造混杂体雏议

榆树沟—铜花山构造混杂体,东西长大于70km,南北宽约25km,是由不同规模的外来和原地岩块组成的。蛇绿岩套则强烈地混杂在变质基质之中,它们通过韧性剪切带或断裂与不同时代的外来岩块相接触,而它们之间无任何热接触现象。蛇绿岩套层序由上而下是沉积岩、火山岩、火成堆积岩和地幔橄榄岩。根据岩石学特征,组成这些外来和原地岩块的奥陶系、志留系、泥盆系和蛇绿岩,形成于弧-盆和活动大陆边缘环境。构造混杂体形成一系列北西西向推覆构造。蛇绿岩与原地岩块通常构成向南和向北推覆的低角度冲掩断层。晚期推覆构造使其更加复杂化。

THE yUSHUGOU-TONGHUASHAN STRUCTURAL MIXTITE IN XINJIANG

This structural mixtite, which is about 25 kilometers wide from the south to the north and about more than 70 kilometers long from the east to the west, is a mixed geologic body formed by some allochthonous and aulochthonous rock masses of all sizes resalted from tectonism. The ophiolite suites, belonging to the allochthonous rock masses, are intensely mixed in the metamorphic base rock masses. Through the ductite shear belts and faults they are in contact with the allochthonous rock masses of various ages. But among them there is no any hydrothermal contact. From upper to lower, the sequence of the ophiolite suites is as follows: sedimentary rocks, volcanic rocks,pyrogenetic accumulation rocks and mantle olivinoid. According to the petrologic characteristics, the Ordovician, Silurian, Devonian and Ophio-lotes made up of these allochthonous and aulochthonous rock masses were formed in the island-arc province and the mobile continental margin regions. The structural mixtites formed a series of the NWW nappe structures overthrust-ing to the north. This ophiolite and the autoch thonous rock masses usually form a low-angle thrust, which shows the multistage overthrustlng to the south or north. The latter nappe structure makes it more complex.