新藏公路128公里岩体地球化学特征及其地质意义  

GEOCHEMICAL CHARACTERISTICS AND IMPLICATIONS OF INTRUSION AT THE 128 KM SIGN OF XINJIANG-TIBET HIGHWAY

作　　者：王元龙[1] 张旗[1] 成守德[2] 王焰[3] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]新疆维吾尔自治区地质矿产勘查开发局地质矿产研究所,新疆乌鲁木齐830000 [3]香港大学地球科学系

出　　处：《新疆地质》2003年第4期387-392,共6页Xinjiang Geology

基　　金：国家"973"项目(G199904320605);中国科学院知识创新工程基金(KZCX2SW119)共同资助

摘　　要：新藏公路128公里岩体是西昆仑加里东构造带内一个具有代表性的岩体.研究表明,该岩体主要由石英闪长岩、石英二长岩和花岗闪长岩组成,岩体富Al、Sr和LREE,贫Y和HREE,具弱的负Eu异常,其地球化学特征的综合指标类似于埃达克岩(adakite)的特征,可称之为类埃达克岩或埃达克质岩(adakite-like).岩体的成因可能与西昆仑板块的消减作用有关,产于一个具有加厚地壳的活动陆缘环境,主要由下地壳底部中基性岩部分熔融形成,推测地壳厚度约在40 km左右,花岗岩熔融之后留下的残留物可能由角闪石+辉石±石榴石±斜长石组成.The intrusion at the 128 km sign of the Xinjiang-Tibet highway is representative for the Caledonian western Kunlun tectonic belt. The intrusion consists of quartz diorite, quartz monzonite and granodiorite, which are enriched in Al, Sr and LREE but poor in Y and HREE with slight negative Eu anomaly, similar to the geochemical characteristics of adakite. The rocks then can be considered as adakite-like rocks. It is suggested here that the.intrusion formed in an active continental margin with a thickened crust about 40 km in depth which was caused by the subduction of West Kunlun plate. The intrusion was derivation from the partial melting of intermediate-mafic rocks in the bottom of the lower crust, and the relicts are probably composed of hornblende+pyroxene眊arnet眕lagioclase.

关 键 词：岩体 地球化学特征 地质意义 加里东期 埃达克质岩 活动陆缘 

分 类 号：P595[天文地球—地球化学] P542[天文地球—地质学]