南秦岭佛坪片麻岩穹隆变质作用及与岩浆作用的关系  

Metamorphism and Its Relation of Magmatism of the Foping Gneiss Dome in the South Qinling Tectonic Belt

作　　者：陈龙耀[1] 刘志慧 刘晓春[1] 刘树文[3] Chen Longyao;Liu Zhihui;Liu Xiaochun;Liu Shuwen(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Department of Environmental Sciences,Hebei University of Envir omental Engineering,Qinghuangdao 066102,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]河北环境工程学院环境科学系,河北秦皇岛066102 [3]北京大学地球与空间科学学院,北京100871

出　　处：《地球科学》2019年第12期4178-4185,共8页Earth Science

基　　金：国家重大基础研究发展规划项目(No.2015CB856104);国家自然科学基金项目(No.41872059)

摘　　要：南秦岭佛坪片麻岩穹隆是国内片麻岩穹隆的典型代表之一,记录了碰撞造山到后造山伸展等多阶段构造演化信息,对揭示秦岭造山带早中生代构造演化具有重要的意义.岩石组合、岩相学、矿物化学和传统温压计研究表明,佛坪片麻岩穹隆具有明显的变质分带特征,以穹隆核部为中心,向南北两侧的盖层变质温度逐渐降低,压力并没有出现随地温梯度的相应变化.不同类型岩石的锆石LA-ICP-MS U-Pb定年和变泥质岩的独居石SHRIMP U-Pb定年给出了一致的变质时代,为206~196 Ma.结合南秦岭早中生代岩浆作用研究,认为佛坪片麻岩穹隆递增变质作用与三叠纪末期的岩浆底辟有关,片麻岩穹隆形成于后碰撞伸展环境.The Foping gneiss dome in the South Qinling tectonic belt is one of the most typical gneiss domes.The gneiss dome has records the multi-stage tectonic evolution from syn-collision orogeny to post-orogenic extension,and therefore is critical to understanding the Early Mesozoic tectonic evolution of the Qinling orogen.The studies on field work,petrography,mineral chemistry,and conventional geothermobarometry show that Foping gneiss dome has typical metamorphic zoning,with metamorphic temperature gradually decreasing from the Precambrian basement in the core to the sedimentary covers in the north and south flanks.Zircon LA-ICP-MS U-Pb dating of different types of rocks and monazite SHRIMP U-Pb dating of the metapelites give a consistent metamorphic age of ca.206-196 Ma.In combination with the investigation of Early Mesozoic granitoids in the South Qinling tectonic belt,the authors infer that the metamorphism of the Foping gneiss dome was induced by Late Triassic magmatic diapir in a post-collisional extensional setting.

关 键 词：南秦岭构造带 佛坪 片麻岩穹隆 变质分带 岩石学 

分 类 号：P581[天文地球—岩石学] P586[天文地球—地质学]