云南个旧高峰山花岗岩成因:锆石U-Pb年代学及地球化学约束  

Petrogenesis of the Gaofengshan granite in Gejiu area,Yunnan Province:Zircon U-Pb dating and geochemical constraints

作　　者：李肖龙[1] 毛景文[1,2] 程彦博[1] 张娟[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《岩石学报》2012年第1期183-198,共16页Acta Petrologica Sinica

基　　金：国家自然科学基金重点项目(40930419);国土资源部公益性行业科研专项(200911007-12);云南锡业集团有限责任公司科研项目(2010-04A);中央高校基本科研业务费专项资金资助(2-9-2010-21);大型矿集区时空结构与巨量金属富集机理研究(1212011120994)联合资助

摘　　要：高峰山花岗岩体位于个旧矿区东区高松矿田南部,为一隐伏岩体,岩性主要为中粒黑云母二长花岗岩。本文对该岩体进行年代学、地球化学研究以约束其形成时代和岩石成因。锆石LA-ICP-MSU-Pb定年获得的形成年龄为85.76±0.58Ma,即白垩纪晚期。地球化学数据显示,高峰山花岗岩具有高硅富碱的特点,属于准铝质到过铝质的高钾钙碱性花岗岩;并富集Rb、U、Ta、Pb、Nd,而亏损Ba、Nb、Sr、P、Zr、Eu、Ti;稀土元素总量为(∑REE)为146.7×10-6～236.1×10-6,铕负异常非常明显(δEu为0.03～0.11),具有类似M型的四分组效应。初步研究表明,高峰山花岗岩具有A2型花岗岩的特征,是地壳部分熔融形成的母岩浆经高程度的分离结晶作用形成的,是晚中生代华南西部岩石圈拉张伸展的地球动力学背景下,滇东南-桂西一带大规模岩浆活动-成岩事件的产物。The Gaofengshan granite is located in the eastern part of the Gejiu ore district,Yunnan Province.The lithology of the granitoid is mainly medium grained biotite monzonitic granite.In this paper,zircon U-Pb dating and geochemistry of the Gaofengshan granite is studied to constrain its geochronology and petrogenesis.Zircon LA-ICP-MS dating yields an emplacement age of 85.76±0.58Ma,which suggests that this granite formed in the Late Cretaceous.Geochemically,this granite is silica riched in composition, with high content of alkali（Na 2 O＋K2 O）.It’s a metaluminous to peraluminous granite and belongs to the high-K calc-alkaline series, and characterized by enrichment of Rb,U,Ta,Pb,Nd and depletion of Ba,Nb,Sr,P,Zr,Eu,Ti.The abundance of∑REE varies in the range of 146.7×10 -6 to 236.1×10 -6 ,and it has intensely negative Eu abnormality（δEu=0.03～0.11）.What’s more,it reflects a tetrad-like effect with a shape of＂M＂.These features are coincident with A2 granite.Geochemical characteristics show that the parental magma of the Gaofengshan granite was derived from the partial melting of crust,and experienced a strong crystal fractionation process.New data of this study indicate that the Gaofengshan granite was one component of the large scale Late Cretaceous magmatism in western Cathaysia block,which viewed as under a regional lithospheric extension tectonic setting.

关 键 词：高峰山花岗岩 锆石U-PB年龄 地球化学 岩石成因 云南个旧 

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