博格达山东段石炭纪火山岩地球化学及构造属性

GEOCHEMISTRY AND STRUCTURE CHARACTERISTIC OF CARBONIFEROUS VOLCANIC ROCKS IN THE EASTERN OF BOGEDA MOUNTAIN

博格达东段石炭系火山岩发育,通过1:5万区域地质调查工作,将该区划分为3个组,即下石炭统七角井组、上石炭统下部柳树沟组及上石炭统中上部祁家沟组.文中对3组地层中火山岩地质及岩石学、主量元素、稀土元素、微量元素地球化学特征研究表明,下石炭统七角井组、上石炭统下部柳树沟组是以拉斑玄武岩为主的双峰式火山岩建造,上石炭统中上部祁家沟组是小范围火山岩-碎屑岩-碳酸盐岩建造,各组火山岩均为钙碱性拉斑系列,岩浆源是幔源岩浆与地壳物质混合物,形成环境为板内裂谷环境.

Carboniferous volcanics rocks are widely distributed in the eastern area of Bageda Mountain with the lower level of research.According to 1：50000 region geological surveys,we are individed Carboniferous rock into three formations, namely the Lower Carboniferous Qijiaojing formation, the Upper Carboniferous Liushugou formation, The middle-upper part of the Upper Carboniferous Qijiagou formation. In this article, the volcanic rock geology and petrology, major element, REE, trace elements geochemistry characteristics are studied.The results show that the Lower Carboniferous Qijiaojing formation and the Upper Carboniferous Liushugou formation are bimodal volcanic construction and the major of tholeiite.The Upper Carboniferous Qijiagou formation is volcanic rock-Clastic-carbonate construction with small scope. All volcanic rocks within research area are series of lime-alkali tholeiite.The source of magma is mixture by mantle-derived magma with crust material.The diagenetic eniverment is in intraplate rift.