摘要
本文对湖北省北部蓝片岩带的区域分布、产出层位,蓝片岩类型、矿物组合与沉积建造的关系,蓝片岩变质特征及形成地质构造环境等进行了详细讨论。本区蓝片岩带主要产于上震旦统(陡山沱组)、耀岭河群、武当群(上部双台组)三个层位,它赋存于富含Na_2O(2～7％)及较高的Fe_2O_2/FeO比值为共同特征的岩石中。蓝片岩带的形成始于中元古代,在早期由于扬子地台与华北地台之间发生裂陷槽,沉积了巨厚的酸性火山岩,中期继续拉张沉陷,发育了硅、泥质岩及拉斑玄武岩,至晚元古代末期地槽闭合,南、北大陆重新拼合,伴随产生强大的挤压应力而发生变质作用,至此蓝片岩变质带即告完成。
The blueschist belt in northern Hubei mainly occurs in the upper Sinian Doushantuo Formation, Yaolinghe Group and Wudang Group (the upper part of which is the Shuangtai Formation). It is localized in the rocks characterized by rich Na_2O (2-7%) and a higher Fe_2O_3/FeO ratio. The belt began to form in the middle Proterozoic. In the early stage there occurred a rift trough between the Yangtze platform and North China platform, in which very thick acid volcanic rocks were deposited. In the middle stage, extension and subsidence continued and thus there developed siliceous and pelitic rocks and tholeiite. By the terminal late Proterozoic, the trough closed and the northern and southern continents were assembled again, accompanied by strong compressive stress which brought about metamorphism. By that time a blueschist belt was formed.
出处
《中国区域地质》
CSCD
1990年第3期255-261,共7页
Regional Geology of China
