内蒙古赤峰北部晚侏罗世花岗岩地球化学特征及构造背景  

GEOCHEMICAL CHARACTERISTICS AND TECTONIC SETTING OF UPPER JURASSIC GRANITE FROM NORTHERN CHIFENG,INNER MONGOLIA

作　　者：刘昊[1] 杨欣德[2] 郝彬[1] 刘贵权[1] 李勇锋[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京10083 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地质力学学报》2011年第3期286-294,共9页Journal of Geomechanics

基　　金：中国地质调查局"内蒙古炒米房幅;土城子幅;新开地幅;大黑水幅1:50000区域地质调查"项目(编号:1212011120661)资助

摘　　要：通过内蒙古赤峰北部地区花岗岩地球化学数据与国内外各类型花岗岩资料的对比和判别,认为内蒙古赤峰北部地区花岗岩以I型为主,少数具有A型花岗岩的特征。具有高钾和富碱的特点,微量元素表现为富集Ba、Th、K等大离子亲石元素(LILE),而高场强元素(HFSE)Nb、Ti等则相对亏损,其中Sr和P出现强烈亏损。轻重稀土分馏明显,重稀土未见明显分馏。Eu有明显的负异常(δEu值在0.30～0.88之间),稀土模式呈现为明显的Eu异常右倾谱系。结合前人的研究资料,初步认为在造山后的伸展减薄环境中,压力的降低和软流圈的上涌对地壳的部分熔融起到了一定的作用,从而为研究区花岗岩的形成提供了条件。Comparison geochemical characteristics of granite from northern Chifeng,Inner Mongolia with various type of granite at home and abroad and the discrimination show that most of the Chifeng granite belongs to I-type granite,and a small number of A-type with.It is with the characteristic of high-K and alkali.The trace elements is rich in Ba,Th,K and other large ion lithophile elements（LILE）,while the high field strength elements（HFSE） Nb,Ti,etc.are relatively depleted,which appear strongly depleted in Sr and P.LREE fractionation significantly,no significant fractionation of heavy rare earth.Significant negative Eu anomalies（δEu between the 0.3-0.843）,REE patterns show significant Eu anomalies for the right-wing pedigree.Integrating the outcome of this paper and previous studies,we infer that the granite formed under the stretching and thinning environment.In this process,reducing the pressure and the upwelling of asthenosphere partial melting of the crust plays a role,so as to provide the conditions for the formation of granite.

关 键 词：内蒙古赤峰地区 花岗岩 地球化学特征 构造环境 

分 类 号：P584[天文地球—岩石学]