哀牢山深变质带内两类晚渐新世花岗岩成因及其构造指示  

Petrogenesis of two types of late Oligocene granites in Ailaoshan tectonic zone and their tectonic implications

作　　者：郭小飞[1,2,3] 王岳军 刘汇川 张玉芝 GUO Xiaofei;WANG Yuejun;LIU Huichuan;ZHANG Yuzhi(State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;;School of Earth Sciences and Engineering, Guangzhou 510275, China;University of Chinese Academy of Sciences, Beijing 100049, China;Guangdong Provincial Key Lab of Geodynamics and Geohazards, Sun Yat sen University,Guangzhou 510275, China)

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中山大学地球科学与工程学院,广东广州510275 [3]中国科学院大学,北京100049 [4]广东省地球动力作用与地质灾害重点实验室,广东广州510275

出　　处：《中山大学学报（自然科学版）》2017年第6期1-14,共14页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：国家重点研发计划项目(2016YFC0600303);国家重点基础研究发展计划(973)项目(2014CB440901);国家自然科学基金联合基金(U170160005);中山大学高校基本业务费项目

摘　　要：红河-哀牢山构造带发育了广泛的、与印度欧亚板块碰撞造山作用紧密相关的新生代构造-岩浆作用,出露于云南哀牢山变质带中段的两个花岗岩样品锆石U-Pb定年结果分别为26.2±0.5 Ma和26.8±0.5 Ma,说明哀牢山变质带并不全是扬子板块结晶基底的下元古界,也存在新生代岩浆岩。花岗岩锆石ε_(Hf)(t)分别为+0.3^+6.9和-9.8^-0.7,平均为+3.4和-4.3,其二阶段模式年龄T_(DM2)分别为526~853 Ma和903~1 355 Ma。低ε_(Hf)(t)花岗岩源岩可能是元古宙哀牢山群变质杂砂岩,高ε_(Hf)(t)花岗岩源自软流圈地幔热源加热诱发的新生下地壳部分熔融。结合前人研究成果,认为晚渐新世红河剪切带剪切作用切穿了岩石圈地幔;渐新世印支地块两侧的高黎贡山和哀牢山走滑剪切系统肢解了东南亚不同的块体,为印支地块向东南方向的挤出创造了条件。The widespread Cenozoic magmatism in the Red River Ailaoshan tectonic zone is closely related to the Indian Eurasian plate collision orogeny.Zircon U Pb dating results of two granitic samples exposed in the middle part of the Ailaoshan metamorphic belt are262±05Ma and268±05Ma,respectively.This indicates that the Ailaoshan metamorphic zone is not entirely attributed to the Proterozoic crystalline basement of the Yangtze block,while it also contains Cenozoic magmatic rocks.ZirconεHf(t)values of the samples range from+03to+69and from-98to-07with mean values of+34and-43,respectively and their corresponding two stage Hf model ages(TDM2)range from526to853Ma and from903to1355Ma.The highεHf(t)granites were derived from partial melting of juvenile crust induced by the asthenospheric mantle heat source,while lowεHf(t)granites from Proterozoic metamorphic sandstones of the Ailaoshan group.In combination with previous research results,we suggest that the Red River fault has cut across the lithosphere mantle.In SE Asia,the Gaoligongshan and Ailaoshan strike slip shear zones on both sides of Indosinian block dismembered different blocks and created conditions for their Oligocene extrusion to the southeast.

关 键 词：哀牢山构造带 花岗质岩石 锆石年龄 HF同位素 走滑剪切 挤出效应 

分 类 号：P588121[天文地球—岩石学]