扬子板块西缘挖角地区晋宁期岩浆作用及大地构造意义  

The magmatism and tectonic significance of Jinningian monzogranite in Wajiao area,western margin of Yangtze Block

作　　者：谢其锋[1,2] 蔡元峰[3] 董云鹏[1] 吴灌洲 翟明国[1,5] XIE QiFeng;CAI YuanFeng;DONG YunPeng;WU GuanZhou;ZHAI MingGuo(State Key Laboratory of Continental Dynamics,Northwest University,Xi＇an 710069,China;College of Zijin Mining,Fuzhou University,Fuzhou 350108,China;State Key Laboratory for Mineral Deposits Research,Nanjing University,Nanjing 210046,China;Chendu Engineering Corporation Limited,Power China,Chendu 610072,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]西北大学大陆动力学国家重点实验室,西安710069 [2]福州大学紫金矿业学院,福州350108 [3]南京大学内生金属矿床成矿机制研究国家重点实验室,南京210046 [4]中国电建集团成都勘测设计研究院有限公司,成都610072 [5]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩石学报》2018年第11期3287-3301,共15页Acta Petrologica Sinica

基　　金：西北大学大陆动力学国家重点实验室开放课题基金;南京大学内生金属矿床成矿机制研究国家重点实验室开放课题基金(20-15-05)联合资助

摘　　要：四川省石棉县挖角地区花岗岩体位于扬子板块西缘与松潘-甘孜地块的结合部位,本文通过详细的野外地质调查,结合岩石学、岩相学、LA-ICP-MS U-Pb年代学和MC-ICP-MS Hf同位素组成研究,厘定了岩体形成时代,探讨了岩浆来源。LA-ICP-MS锆石U-Pb测年结果表明,挖角二长花岗岩形成年代介于852±33Ma和847±44Ma之间,处于晋宁期晚青白口世,与全球Rodinia期泛大陆形成密切相关。锆石原位Lu-Hf同位素组成表明,2个样品的εHf(t)值分别为+3. 9～+9. 3和-8. 0～+6. 5,为典型的壳-幔混合型; Hf同位素的二阶段模式年龄(tDM2)分别为1. 14～1. 49Ga和1. 33～2. 24Ga,均值分别为1. 32Ga和1. 52Ga,表明岩浆源区以中元古代古老地壳基底的部分熔融为主,形成过程中有幔源及古元古代古老地壳物质的贡献。挖角地区晋宁期二长花岗岩体锆石U-Pb年代学和Hf同位素组成,反映了扬子板块西缘晚青白口世岩浆活动期和源区特征,其成因与全球Rodinia泛大陆形成期间岩浆活动和与壳幔混合作用密切相关。本文研究成果,为解释扬子板块西缘的构造演化提供了新的资料证据。The Wajiao monzogranite pluton is located in the junction part of the western margin of Yangtze Block and Songpan-Ganzi Block,in Shimian County,Sichuan Province,China. In the paper,based on the detailed field geological survey,combined with the petrology,petrography,LA-ICP-MS U-Pb chronology and MC-ICP-MS Lu-Hf isotopic analysis,the forming age and its magmatic source was discussed. LA-ICP-MS zircon U-Pb dating results show that Wajiao monzogranite pluton formed between 847 ± 44 Ma and852 ± 33 Ma,belongs to strong magmatic activity during period of the Late Qingbaikouan in Jinning Epoch,which closely related to the global Rodinia continent. In-situ zircon Lu-Hf isotopic analysis results show that the value of εHf（ t） were ＋ 3. 9 ～ ＋ 9. 3 and-8. 0 ～＋ 6. 5,respectively,the characteristic with crust-mantle mixed type typical; zircon Hf isotope two-stage model ages（ tDM2） were 1. 14～ 1. 49 Ga and 1. 33 ～ 2. 24 Ga,respectively,the mean value of 1. 32 Ga and 1. 52 Ga,showed that magmatic source dominated by partial melting of ancient crust substrate mainly,may be associated with crust derived magma and ancient crustal rocks contribution in the period of Paleoproterozoic and Mesoproterozoic. The zircon U-Pb chronology and Lu-Hf isotopic characteristic of Jinning Epoch from Wajiao area,reflected magmatism temporal and magmatism source characteristics of the Qingbaikouan Period in the western margin of Yangtze Block,and its origin was closely correlated to the formation of global Rodinia continent and the evolution of magma activity.The results of the paper,which can provide new data evidence of granite source and regional tectonic evolution of the Yangtze Plate in Wajiao area,Sichuan Province.

关 键 词：二长花岗岩 锆石U-Pb年龄 LU-HF同位素 晋宁期 挖角地区 四川省 

分 类 号：P599.121[天文地球—地球化学] P597.3[天文地球—地质学]