塔里木地块东南缘新太古代安南坝石英闪长片麻岩的成因及其对地壳演化的启示  

Petrogenesis of Neoarchean Ananba Quartz Diorite Gneiss in Southeastern Margin of Tarim: Implications for Crustal Evolution

作　　者：辜平阳[1,2] 计文化 陈锐明[1,2] 庄玉军 彭璇[1,2] 查显锋 郭亚鹏 Gu Pingyang;Ji Wenhua;Chen Ruiming;Zhuang Yujun;Peng Xuan;Zha Xianfeng;Guo Yapeng(Center for Orogenic Belt Geology,CGS,Xi'an Geological Survey Center,Xi'an 710054,China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MNR,Xi'an Geological Survey Center,Xi'an 710054,China)

机构地区：[1]中国地质调查局造山带地质研究中心,西安地质调查中心,陕西西安710054 [2]自然资源部岩浆作用成矿与找矿重点实验室,西安地质调查中心,陕西西安710054

出　　处：《地球科学》2020年第9期3268-3281,共14页Earth Science

基　　金：国家自然科学基金项目(No.41002063);陕西自然科学基金项目(No.2017JM4001);中国地质调查局地质调查项目(Nos.DD20190069,1212011121193)。

摘　　要：目前塔里木地块东南缘早前寒武纪岩石形成时代和成因机制研究较为薄弱,制约了人们对塔里木大陆地壳形成和早期演化的认识.岩石地球化学及锆石Hf同位素组成表明塔里木地块东南缘安南坝石英闪长片麻岩原岩岩浆为下地壳变玄武岩部分熔融形成,并有少量幔源物质的加入. LA-ICP-MS锆石U-Pb测年结果显示石英闪长片麻岩成岩年龄为2 662±12Ma、2 676±15 Ma,结合已有资料综合说明塔里木东南缘太古宙岩石形成时代主要集中在2.55~2.70 Ga,变质年龄分别为1 980±30 Ma、1 828±20 Ma^2 087±29 Ma,是古元古代中晚期与造山作用有关的岩浆-变质事件的地质记录.石英闪长片麻岩中锆石两阶段模式年龄TDM2为2 954~3 742 Ma,峰值为~3.24 Ga,据此认为~3.2 Ga是塔里木东南缘大陆地壳生长的主要时期,并于2.55~2.70 Ga发生地壳再造,古老地壳再循环可能是该地区新太古代中晚期大陆地壳演化的重要方式.The study on the formation age and petrogenetic mechanism of early Precambrian rocks in the southeast margin of Tarim block is relatively weak,which restricts the understanding of the formation and early evolution of continental crust. These geochemistry and zircon Hf isotope compositions show that primary magma of the quartz diorite gneiss was formed by partial melting of the lower crust meta-basalt with minor addition of mantle-derived materials. LA-ICP-MS zircon U-Pb dating results reveal that the diagenetic ages of the quartz diorite gneiss are 2 662±12 Ma and 2 676±15 Ma,indicating the Archean rock formation ages in the southeastern margin of Tarim were mainly concentrated in 2.55-2.70 Ga;corresponding metamorphic ages are 1 980±30 Ma and 1 828±20 Ma-2 087±29 Ma respectively,representing the geological record of magmatic-matamorphic events related to orogenic processes in the middle and late period of Paleoproterozoic in the southeastern margin of Tarim.Additionally,two-stage model ages(TDM2)of zircon for the quartz diorite gneiss in this study vary from 2 954 to 3 742 Ma,with peak ages clustering at ~3.24 Ga. Thus,combined with the available data,it is suggested that the ~3.2 Ga age represents the main period of continental crustal growth in the southeastern margin of Tarim,and subsequently crustal reconstruction occurred in 2.55-2.70 Ga. It is concluded that ancient crustal material recycling could be an important way of continental crustal evolution in the middle and late period of Neoarchean in this area.

关 键 词：石英闪长片麻岩 岩石学 地球化学 锆石U-Pb年龄 Hf同位素 塔里木东南缘 

分 类 号：P581[天文地球—岩石学]