柴北缘欧龙布鲁克地块中元古代晚期麻粒岩相变质作用——来自石榴夕线堇青石片麻岩的岩石学、相平衡模拟和U-Pb年代学的制约  

Late Mesoproterozoic granulite-facies metamorphism in the Oulongbuluke block of the North Qaidam Mountains:Constraints from petrology,phase equilibrium modeling and U-Pb dating of garnet-sillimanite-cordierite gneisses

作　　者：毛小红[1] 路增龙 张建新[1] 郭祺 武亚威 MAO Xiao-hong;LU Zeng-long;ZHANG Jian-xin;CUO Qi;WU Ya-wei(Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Sino-Zijin Resources Ltd.,Beijing 100012,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研究所自然资源部深地动力学重点实验室,北京100037 [2]中色紫金地质勘查(北京)有限责任公司,北京100012 [3]北京大学地球与空间科学学院,北京100871

出　　处：《岩石矿物学杂志》2024年第2期219-237,共19页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(42102246,42202058);中国地质科学院基本科研业务费项目(JKYZD202310);中国地质科学院地质研究所基本科研业务费项目(J2319)。

摘　　要：在欧龙布鲁克地块乌兰北部地区察汗河岩群中识别出麻粒岩相石榴夕线堇青石片麻岩,其矿物组合为石榴子石、夕线石、堇青石、黑云母、斜长石、钛铁矿和少量钾长石等。岩相学观察显示,M1阶段矿物组合有斜长石±钾长石+石榴子石+夕线石+石英,M2阶段矿物组合有斜长石±钾长石+石榴子石+夕线石+石英+钛铁矿+黑云母,M3阶段矿物组合有堇青石+黑云母+钛铁矿+石英+石榴子石+斜长石±钾长石。相平衡模拟计算结果显示,该岩石的峰期温压条件为p=0.92~1.08 GPa,峰期温度t>790℃,峰期之后经历升温降压的p-T演化轨迹。锆石和独居石LA-ICP-MS U-Pb年代学研究获得的变质年龄分别为1133±14 Ma和1125±37 Ma,1133~1125 Ma应代表了该期麻粒岩相变质作用的时代。结合区域地质资料和已有的研究成果,我们认为乌兰北部察汗河岩群的石榴夕线堇青石片麻岩可能形成于大洋俯冲作用下的弧或弧后构造环境,乌兰北部的岩浆-变质杂岩带经历了从中元古代晚期-新元古代早期俯冲增生到碰撞造山的演化过程,是全球Rodinia超大陆汇聚过程的响应。The garnet-sillimanite-cordierite gneiss,which has been identified from the Chahanhe Group in the northern region of the Oulongbuluke block,consists of garnet,sillimanite,cordierite,biotite,plagioclase,ilmenite,and a small amount of K-feldspar.Petrographic observation shows that three stages(M1,M2 and M3)of mineral assemblage can be recognized.They are M1:Pl±Kfs+Grt+Sill+Qz,M2:Pl±Kfs+Grt+Sill+Qz+Ilm+Bt,and M3:Crd+Bt+Ilm+Qz+Grt+Pl±Kfs.Phase equilibrium modelling shows that the peak p-T conditions of the garnet-sillimanite-cordierite rock are p=0.92~1.08 GPa and t>790℃,and experienced a heating decompression during exhumation.The metamorphic ages acquired from zircon and monazite U-Pb dating by LA-ICP-MS are 1133±14 Ma and 1125±37 Ma,respectively,which represent the timing of granulite-facies metamorphism.Combining regional geology with our data,we suggested that the garnet-sillimanite-cordierite rock in the Chahanhe Group formed in an arc or back-arc system related to oceanic subduction.The magmatic-metamorphic complex belt in the northern region of the Oulongbuluke block underwent an evolutionary process from subduction-accretion to collision orogeny during late Mesoproterozoic to early Neoproterzoic,which is a response to the convergence process of Rodinia supercontinent.

关 键 词：欧龙布鲁克地块 石榴夕线堇青石片麻岩 麻粒岩相 RODINIA超大陆 相平衡模拟 

分 类 号：P588.34[天文地球—岩石学]