岩浆混合作用与火成岩多样性的耦合关系:以东昆仑造山带白日其利长英质岩体为例  

Coupling Relation between Magma Mixing and Igneous Petrological Diversity:An Example of Bairiqili Felsic Pluton in East Kunlun Orogen

作　　者：陈兵[1] 熊富浩[1,2] 马昌前 陈越[1] 黄虎 Chen Bing;Xiong Fuhao;Ma Changqian;Chen Yue;Huang Hu(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059 [3]中国地质大学地球科学学院,湖北武汉430074

出　　处：《地球科学》2021年第6期2057-2072,共16页Earth Science

基　　金：国家自然科学基金(Nos.41602049,41972066);中国博士后科学基金(No.2015M582529).

摘　　要：壳-幔岩浆相互作用如何影响长英质火成岩的岩石学多样性是当前岩石学研究的焦点问题之一.以岩石类型丰富的东昆仑白日其利长英质岩体和暗色微粒包体为研究对象,开展系统的锆石U-Pb年代学、矿物学、全岩元素地球化学和Sr-NdHf同位素研究,探讨和解析这一重要科学问题.LA-ICPMS锆石U-Pb年代学研究表明,暗色微粒包体(247.8±2.0 Ma)与二长花岗岩(247.5±1.4 Ma)、花岗闪长岩(248.8±2.1 Ma)和石英闪长岩(248.8±1.5 Ma)均侵位结晶于早三叠世.岩相学和矿物学研究表明,白日其利长英质岩石与包体的成因机制与壳-幔岩浆的机械或化学混合作用密切相关.元素地球化学和Sr-NdHf同位素组成研究揭示,幔源镁铁质岩浆端元起源于受俯冲板片流体交代的富集地幔熔融,而壳源长英质岩浆端元则起源于东昆仑古老的变质杂砂岩基底.岩石成因分析揭示,幔源镁铁质岩浆侵入长英质晶粥岩浆房,促使长英质晶粥发生活化,随后壳-幔岩浆端元以不同比例和不同方式发生机械和化学混合等相互作用,从而形成镁铁质岩墙、包体、石英闪长岩和花岗闪长岩等多种岩石类型.晶粥状态下壳-幔岩浆相互作用是控制东昆仑长英质火成岩多样性和大陆地壳生长演化的重要方式.How crust-mantle magma interaction controls the petrological diversity of the felsic igneous rocks is one of the key scientific issues in petrology research.In this study it takes the Bairiqili felsic pluton which is characterized by its various rock types,as well as its mafic microgranular enclaves(MMEs)in East Kunlun as the research object,and presents its zircon U-Pb chronology,mineralogy,whole-rock geochemistry and Sr-Nd-Hf isotopic data to discuss the key scientific issue.LA-ICPMS zircon U-Pb geochronology indicates that the MMEs(247.8±2.0 Ma),monzogranite(247.5±1.4 Ma),granodiorite(248.8±2.1 Ma)and quartz diorite(248.8±1.5 Ma)all emplaced and crystallized in Early Triassic.Petrographic and mineralogical studies show that the petrogenesis of the felsic rocks and MMEs is closely related to the crust-mantle magma mixing or mingling.Elemental and Sr-Nd-Hf isotopical geochemistry reveals that the mafic magma was originated from partial melting of the enriched mantle which was metasomatized by subduction-related fluid,while the felsic end-member magma was derived from partial melting of the ancient metagreywackes.This study proposes that the mantle-derived mafic magma firstly intruded into the felsic crystal mushy magma chamber,promoting the rejuvenation of this felsic crystal mush.Subsequently,the mixing and mingling interaction occurred between the crust and mantle end-member magmas in different proportions and in different ways,thus formed a variety of igneous rocks including mafic dyke,MMEs,quartz diorite and granodiorite.Crust-mantle magma interaction in crystal mushy state is an important way to control the petrological diversity of felsic rocks and the growth and evolution of continental crust in East Kunlun.

关 键 词：岩浆混合 岩石多样性 花岗岩 暗色微粒包体 东昆仑 

分 类 号：P581[天文地球—岩石学]