藏北新生代两套钾玄质火山岩系列地球化学特征  

THE GEOCHEMICAL CHARACTERISTICS OF CENOZOIC SHOSHONITIC ROCKS IN NORTHERN TIBET

作　　者：刘燊[1] 胡瑞忠[1] 迟效国[2] 李才[2] 冯彩霞[1] 

机构地区：[1]中国科学院地球化学研究所 [2]吉林大学地球科学学院,吉林长春130061

出　　处：《矿物岩石》2003年第2期66-71,共6页Mineralogy and Petrology

基　　金：原地矿部"九五"基础研究重点项目 ( 95 0 110 1-5 );中科院知识创新项目 ( KZCX2 -10 2 )

摘　　要：岩石学和元素地球化学特征研究表明 ,藏北新生代自南向北沿可可西里岩带和喀喇昆仑 -玉门岩带出露有两套钾玄质系列火山岩。它们富集大离子亲石元素 (L IL E)和轻稀土 (L REE)及明显亏损 Nb- Ta- Ti,同时具有板内和岛弧 (陆弧 )的双重特征。源区来源于可能与俯冲带流体有关的相似交代富集地幔 ,成岩过程主要经历了低度 (<10 % )辉石分离结晶作用 ,同时 ,源区伴有地壳物质的混染作用。The characteristics of petrology and elemental geochemistry indicated that, from south to north, there are two belts of Cenozoic shoshonitic rocks in northern Tibet,the Hohxil shoshonite belt and Karakunlun-Yumen shoshonite belt. Both of them were rich in LILE and LREE, and poor in Nb-Ta-Ti, which showed the features of intraplate and Insland arc (continental arc). They were generated from similar enriched metasomatiic mantle source related with the fluid of subduction belt. Their genesis was mainly controlled by low degree fractional crystallization (<10%) of CPX with hydration of crust.

关 键 词：新生代 钾玄质火山岩 岩石学 元素地球化学 西藏 交代作用 地壳混染作用 

分 类 号：P588.14[天文地球—岩石学] P595[天文地球—地质学]