中祁连西段托赖岩群变质岩的原岩恢复及其构造环境

摘要

A study of the nature of the protoliths of metamorphic rocks in the Tuolai Group and their tectonic setting shows that the schist, gneiss, quartzite and marble in metamorphic rocks of the Tuolai Group are originally sedimentary rocks, and the amphibolite in metamorphic rocks of the Tuolai Group is basic volcanic rock. The protolith of schist and gneiss is greywacke, the quartzite is quartz sandstone, the marble is dolostone and limestone, and the amphibolite is basaltic andesite. Discrimination of the tectonic setting of me⁃ta-volcanic rock indicates that the amphibolite formed in an intracontinental rift environment. As the special interlayer of Tuolai Group, the metasedimentary rocks should have the same tectonic environment as the anphibolite, both formed in an extensional basin.%对托赖岩群变质岩的岩石特征及地球化学进行研究，结果显示，托赖岩群中的片岩、片麻岩、石英岩、大理岩的原岩为沉积岩，其中片岩、片麻岩原岩为砂质岩、杂砂岩；石英岩原岩为石英砂屑岩；大理岩原岩为灰岩、白云岩。斜长角闪岩原岩为中基性火山岩，岩性为玄武安山岩。变质基性火山岩的构造环境判别结果表明，其形成于板内环境，作为托赖岩群中的特殊夹层，暗示托赖岩群沉积岩的原岩形成环境与变质火山岩的构造环境一致。