滇西昌宁-孟连古特提斯闭合的岩浆活动响应——来自临沧岩体南段花岗岩的地质地球化学证据  

Response of magmatic activity to the closure of Changning-Menglian Palaeothys in western Yunnan: Evidence from geo-geochemical study on granite in southern section of Lincang pluton

作　　者：苑新晨 杨启军[1,2] 吕勇 潘明[3] 高爱洋[1] 徐放 YUAN Xinchen;YANG Qijun;LYU Yong;PAN Ming;GAO Aiyang;XU Fang(College of Earth Sciences,Guilin University of Technology,Guilin 541006,Guangxi,China;Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials,Guilin 541006,Guangxi,China;Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,Guangxi,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006 [2]有色金属隐伏矿床勘查及材料开发协同创新中心,广西桂林541006 [3]中国地质科学院岩溶地质研究所,广西桂林541004

出　　处：《地质通报》2021年第1期125-137,共13页Geological Bulletin of China

基　　金：中国地质调查局项目《云南1∶5万木戛幅(F47E007015)、澜沧县幅等6幅区域地质调查》(编号:1212011120594)。

摘　　要：临沧花岗岩岩体(简称临沧岩体)是滇西澜沧江地区南段出露面积最大的复式岩基,也是特提斯构造域的重要组成单元,其岩石类型主要为黑云母二长花岗岩。锆石样品得出的定年结果为225.1±6.1 Ma,表明这些花岗岩类侵位于晚三叠世。临沧花岗岩的K2O/Na2O值大于1,铝饱和指数A/CNK=1.05~1.95属高钾钙碱性过铝-强过铝质S型花岗岩。岩石总体上富集轻稀土元素((La/Yb)N=6.06~21.01),亏损重稀土元素,并显示出明显的负Eu异常(δEu=0.20~0.38)。岩石地球化学特征指示,临沧花岗岩应为昌宁-孟连古特提斯封闭过程的产物原岩为中下地壳贫粘土的变质砂岩和变质泥岩,其Pearce构造判别图解中的同碰撞属性是对古特提斯封闭及保山-思茅地块碰撞的响应。Lincang intrusive,as the largest exposed compound batholith of southern Lancangjiang in western Yunnan,and an important component of tethys tectonic domain,is mainly biotite monzogranite in lithology.The zircon sample collected frome granite was dated to 225.1±6.1 Ma,suggesting that these intrusives were emplaced during the Late Triassic.The K2 O/Na2 O value of Lincang granite is greater than 1,and the aluminum saturation index A/CNK ranges froml.05 to 1.95,indicating that Lancang intursives are derived from S-type granite with high potassium calcium basic peraluminum-super peraluminum.Intursives are remarkably characterized by enriched LREE and depleted HREE with(La/Yb)N=6.06~21.01 and 8 Eu of 0.20~0.38.The petro-geochemistry of intusives indicates that the Lincang granite should be the product of the Changning-Menglian Palaeothys closure process,and the original rock of Lincang granite is lithologically clay-poor metamorphic sandstone and metamorphic mudstone in the middle and lower crust.The syncollision represented in its Pearce structure discrimination diagram is a response to the Palaeothys ocean closure and the Baoshan-Simao block collision.

关 键 词：临沧花岗岩 U-Pb锆石年代学 古特提斯洋 陆陆碰撞 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]