东天山觉罗塔格构造带梧桐窝子组岩石化学特征及意义

Petrochemical Characteristics and Significance of Wutongwozi Formation in Jueluotage Tectonic Belt in the East Tianshan

东天山觉罗塔格构造带是我国东天山重要的构造—成矿带,长期以来对构造带的大地构造属性一直存在争议。通过对东天山梧桐窝子组中玄武岩和硅质岩进行较系统的地质和岩石地球化学研究,发现苦水玄武岩为钙碱性系列岛弧环境产物,微量元素显示源区受到俯冲流体混染,而大黑山玄武岩为拉斑系列MORB环境产物,微量元素特征显示该玄武岩源自富集地幔源区。硅质岩具有热液活动的大洋中脊和稳定的大洋盆地2种不同环境下的产物。从其玄武岩和硅质岩岩石化学特征来看,东天山梧桐窝子组应该是洋陆壳混杂堆积的产物,从而说明觉罗塔格地区晚石炭世可能存在洋盆。

East Tianshan Jueluotage tectonic belt is an important tectonic-metallogenic belt in eastern Tianshan,and there have long been disputes about the tectonic attribution of it.Based on the systematical geological and geochemical study on basalt and chert of eastern Tianshan Wutongwozi formation,it concluded that the Kushui basalt was generated from the calc-alkaline series in island arc environment,its trace element showed the source region was mixed with subduction fluid,but Daheishan basalt belong to tholeiite series in MORB environmental,its trace element characteristics display it came from enriched mantle source.The siliceous rocks have products from two different environments of ocean ridge with hydrothermal activity and the stable ocean basins.The petrochemical characteristics of siliceous rocks and basalt indicate that the East Tianshan Wutongwozi formation should be the oceanic and continental crust melange,thus explain the late carboniferous ocean basin could existed in Jueluotage area.