西秦岭北缘甘加—麻当地区玄武岩地球化学特征及成因探讨  

GEOCHEMICAL CHARACTERISTICS AND GENESIS OF BASALTS IN GANJIA-MADANG AREA,NORTHERN MARGIN OF WEST QINLING

作　　者：梁志勇 李鹏举 焦世文 鲁有朋 LIANG Zhi-yong;LI Peng-ju;JIAO Shi-wen;LU You-peng(Engineering Technology Research Center for Exploration and Comprehensive Utilization of Metal and Precious Metal Mineral Resources of Gansu Province,The Third Institude of Geology and Minerals Exploration,Gansu Provincial Bureau of Geology and Minerals Exploration and Development,Lanzhou 730050,China;Gansu Remote Sensing Center for Geological Survey,Lanzhou 730050,China)

机构地区：[1]甘肃省金属贵金属矿产资源勘查与综合利用工程技术研究中心,甘肃省地矿局第三地勘院,甘肃兰州730050 [2]甘肃遥感地质中心,甘肃兰州730050

出　　处：《甘肃地质》2023年第4期13-22,58,共11页Gansu Geology

基　　金：甘肃省科技计划(22YF7GA050);中央引导地方科技发展资金项目(YDZX20216200001297);甘肃省基础地质调查项目(4500689978)联合资助。

摘　　要：西秦岭北缘夏河县甘加—麻当地区零星分布有火山岩,通过对该地区玄武岩开展野外地质调查与室内元素地球化学测试,并进行分析研究表明甘加—麻当玄武岩属于一套钠质—钾质过渡的碱性玄武岩。玄武岩强烈富集大离子亲石元素Rb、W、Sr和高场强元素U、Nb、Ta、Hf,亏损Cs、Ba、Th等元素,显示出典型的OIB型特征,其形成环境为大陆板内环境,推测岩浆起源于亏损的软流圈地幔,其复杂的地球化学特征表明,岩浆经历了较为强烈的岩石圈—软流圈相互作用,与印支期造山运动后岩石圈拉伸有关。Volcanic rocks are scattered in the Gangjia and Madang areas of Xiahe County.Preliminary research shows that the Gangjia-Madang basalt belongs to a set of alkaline basalt with transition from sodium to potassium.The basalt is strongly enriched in large ion lithophile elements Rb,W,Sr and high field strength elements U,Nb,Ta,Hf,while deficient in Cs,Ba,Th elements,showing typical OIB characteristics.Its formation environment is continental plate environment,and it is speculated that the magma originated from the deficient asthenosphere mantle.The magma experienced a relatively strong lithosphere-asthenosphere interaction,which is related to the lithosphere stretching after the Indosinian orogeny.

关 键 词：西秦岭 甘加地区 麻当地区 玄武岩 地球化学 岩石成因 

分 类 号：P588[天文地球—岩石学] P618[天文地球—地质学]