摘要
位于扬子板块西缘的滇西北石鼓变质杂岩主要岩石类型为石英二云片岩、斜长片麻岩、片麻岩、石榴子石云母片岩、石榴石蓝晶石云母片岩等。综合石鼓变质岩岩相学、野外地质和岩石地球化学特征,认为其原岩主要为一套砂质、泥砂质的杂砂岩,含少量的黏土物质。通过4件年龄样品的LA-ICPMS锆石U-Pb测年,显示其变质年龄为863～883Ma,是元古代晚期变质作用的年龄,原岩应为中元古宙变质基底。石鼓变质岩的原岩沉积环境为活动大陆边缘、大陆岛弧。发生在晚元古时期的区域变质作用,应为扬子陆块周缘向扬子陆块俯冲碰撞所致,可能与Rodinia超大陆的形成和裂解过程有关。
The metamorphic complex in Shigu area,Yulong County,northwest of Yunnan Province,is mainly composed of two-mica schist quartz schist,plagioclase gneiss,gneiss and garnet mica schist.The result of the study indicated,by systemic research of petrography,field geology and geochemistry,that the protolith of the Shigu complex is a suite of sand stone,greywacke and a small amount of clay materials.The time got by LA-ICP-MS zircon U-Pb dating of four samples from Shigu metamorphic complex is 863-883 Ma,being the age of metamorphism in Late Proterozoic,suggested that the rocks should be the sedimentary products of Mesoproterozoic.The original rock sedimentary environment or tectonic setting of the Shigu complex might be active continental margin to continental arc.The regional metamorphism that occurred in Late Proterozoic,might caused by the subduction collision of the edge part of Yangtze block to the main Yangtze block during the formation of Rodinia supercontinent.
作者
杨启军
周叔齐
YANG Qijun;ZHOU Shuqi(Nonferrous Metal Concealment Deposits Exploration and MaterialDevelopment Collaborative Innovation Center,Guilin 541006,Guangxi,China)
出处
《矿产与地质》
2019年第1期114-126,共13页
Mineral Resources and Geology
基金
中国地质调查局矿产综合调查项目(编号:12120115024901)资助
