新疆阿尔泰东南缘哈拉乔拉镁铁质岩体地球化学特征与地质意义  

Geochemical Characteristics and Geologic Implications of Halaqiaola Mafic Intrusion,Southeast Altai,Xinjiang

作　　者：夏昭德[1,2] 姜常义[1,2] 卢荣辉[1,3] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]西部矿产资源与地质工程教育部重点实验室,陕西西安710054 [3]四川华源矿业勘查开发有限责任公司,四川成都610072

出　　处：《地球科学（中国地质大学学报）》2012年第5期937-946,共10页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.40534020;40872070);中央高校基本科研业务费专项(No.CHD2010ZY008)

摘　　要：哈拉乔拉镁铁质岩体位于新疆阿尔泰造山带东南缘,主要岩石类型有辉长岩、辉长苏长岩、含长辉石岩、橄榄辉长岩和橄长岩.哈拉乔拉岩体具有低TiO2(0.09%～1.28%)、低碱(Na2O+K2O=0.37%～0.78%)的特点,属于拉斑玄武岩系列;富集大离子亲石元素和轻稀土元素,亏损高场强元素(Nb、Ta等),εNd(t)为-2.62～-0.78,εSr(t)为37.49～45.28.元素地球化学和Nd-Sr同位素组成表明,岩浆源区为被消减板片交代改造过的富集型岩石圈地幔.原生岩浆为高镁拉斑玄武岩浆,岩浆演化过程中主要发生了橄榄石、单斜辉石以及斜长石的分离结晶/堆晶,后期有钛铁矿的析出.Halaqiaola mafic intrusion lies in the southeast margin of the Altai orogenic belt in Xinjiang,northwestern China.The main rock types are gabbros,gabbro norite,plagioclase-bearing pyroxenite,olivine gabbro and troctolite.Halaqiaola intrusion has low contents of TiO2(0.09%-1.28%) and alkali(Na2O+K2O=0.37%-0.78%),and belongs to tholeiitic series;the intrusion is rich in large ion lithophile elements and light rare earth elements and depleted in high field elements(such as Nb,Ta).The εNd(t) and the εSr(t) values range from-2.62 to-0.78 and 37.49 to 45.28 respectively.Element geochemistry and Nd-Sr isotopic composition shows that the magma was derived from the dehydration of subducted plate and metasomatismed enriched lithosphere mantle.The primary magma of the intrusion is basaltic magma.During the process of magma evolution,the primary magma has experienced fractional crystallization of olivine,clinopyroxene and plagioclase,with ilmenite-precipitation in the late period.

关 键 词：哈拉乔拉 镁铁质 原生岩浆 岩浆演化 岩石圈地幔 岩石学 地球化学 

分 类 号：P59[天文地球—地球化学]