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.
出处
《新疆地质》
CAS
CSCD
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
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
intrusion at the 128 km sign, Caledonian, geochemistry, adakite, active continental margin
