北祁连下柳沟-下沟地区火山岩地球化学特征及大地构造意义

摘要

近年来,在青海省北祁连下柳沟-下沟地区新发现了十六条铜多金属矿体,为了总结区域成矿环境,笔者对下柳沟-下沟地区地质背景进行了分析,同时对矿床矿石及含矿岩系的稀土元素、微量元素、稳定同位素、流体包裹体等地球化学特征进行了总结.研究结果显示,本区绢云母(石英)片岩其原岩为一套中-酸性火山岩,而绿泥石片岩原岩为一套中-基性火山岩,容矿火山岩都位于火山弧区,跟俯冲作用有关,表明下柳沟-下沟矿床形成于岛弧环境.%16 Cu-polymetal orebodies were found in the north of Qilian in recent years.In order to sum up the environment of regional metallogeny,the writer analysised the geological background of Xialiugou-Xiagou areas.And the writer studied the chemical feature of the mineral of the deposit and Ore-bearing rock series such as rare-earth element,trace element,stable isotope,fluid inclusion and so on.The research shows that the protolith of Sericite quartz schist is intermediate acidity volcanic rock while the protolith of chlorite schist is intermediate basic volcanic rock.And the ore-hosting volcanic rocks is located on the volcanic arc area and it is in connection with underthrusting.It shows that the deposit is formed in an island arc environment.