新疆乌什塔拉地区中泥盆世火山岩特征及形成环境分析

Features and Formation Environment of Volcanic Rocks from Middle Devonian Epoch in the Area of Wushi Tara,Xinjiang

研究区位于南天山早古生代大洋东段构造带.乌什塔拉地区阿拉塔格组火山岩为超基性—基性岩组合以及中酸性岩组合.其中超基性岩为大洋二辉橄榄岩,基性岩主要为玄武岩,中酸性岩主要有安山岩、英安岩、粗安岩和流纹岩.通过研究分析发现阿拉塔格组火山岩中基性岩产于大洋中脊环境,中酸性火山岩的构造环境应属于活动大陆边缘性质,由于这两套岩石组合均有不同程度的变质变形,以及阿拉塔格组出现的蛇绿岩,可说明这两套火山岩应该不属于同一地区,是由构造拼合而成的.

The study area is located in the eastern section of the South Tianshan Paleozoic Oceanic Tec- tonic Zone. The volcanic rocks of Ala Ata group in its Wushi Tala area belong to uhramafic volcanic rocks, including the combination of basic rocks and the combination of acid rocks. Its uhrabasic rocks are mainly oceanic lherzolite and mafic basalt, its acidic rocks are mainly andesite, dacite, trachya- ndesite and rhyolite. Through this research it is found that the Ala Ata group mafic volcanic rocks were produced in the ocean ridge, but the tectonic setting of acidic volcanic rocks in the group belongs to an active continental margin. Because the two sets of rocks have different degrees of metamorphism and de- formation, especially when the appearance of ophiolite volcanic rocks in the group is considered, we conclude that the two sets should not belong to the same region, but were formed by tectonic piece.