阿尔金构造带西段早古生代侵入岩地球化学特征及构造意义

摘要

Based on 1:250000 regional geological survey of the Washixia and Altyn Tagh sheets indicate that large amounts of Early Paleozoic intrusive rocks are developed in the western segment of Altyn Tagh tectonic belt, and can be divided into three tectonic-magmatic belts.Based on studied their rock associations and geochemistry,the results are fol-lowings:In the northern granite belt,Tatelekebulake granite series is characterized by comagmatic evolution,and it is the product of the syn-collision stage;Qianglike Magma mingling granites in the middle granite belt and Jianshishan granite series in the southern granite belt show magma-mixing characteristics of the different original rocks. They are being the product of the interaction of crust and mantle in subduction-collision stages. The characters mentioned-above indicate that Early Paleozoic intrusive rocks belong to orogenic type granites in the western segment of Altyn Tagh tectonic belt, and their ages can be compared with the times of HP-UHP metamorphism in the western segment of Altyn Tagh tectonic belt, and are the geological record of the ocean-continent subduction-collision in Early Paleozoic. It means that a colli-sion and convergence between the Qaidam plate and the Tarim plate has taken place during Early Paleozoic Era and the HP-UHP metamorphic rocks and large amounts of Caledonian orogenic type granites were formed in this area.%通过1∶25万瓦石峡幅和阿尔金山幅区域地质调查发现，阿尔金构造带西段发育有大量早古生代侵入岩，可划分为3条构造-岩浆岩带。岩石组合和地球化学分析结果表明，北带塔特勒克布拉克花岗岩系列具同源岩浆演化特征，为碰撞造山阶段形成的产物；中带其昂里克浆混花岗岩组合和南带尖石山花岗岩系列显示不同原岩岩浆混合特点，是俯冲-消减阶段到碰撞阶段壳-幔相互作用产物，表明阿尔金构造带西段早古生代侵入岩类属造山型花岗岩，时代与阿尔金地区高压-超高压变质作用时间可对比，是早古生代洋陆俯冲-碰撞的地质记录。说明塔里木和柴达木板块间在早古生代存在板块的汇聚碰撞，形成了该区高压-超高压变质岩和广泛发育的加里东期造山型花岗岩。