摘要
文章对青海共和盆地东部曲乃亥花岗闪长岩体的岩石学、岩石地球化学、年代进行了研究,其结果表明:曲乃亥花岗闪长岩LA-ICP-MS锆石U-Pb定年239.4 Ma±2.8 Ma(n=16,MSWD=0.29),表示该岩体形成于中三叠世;岩石的主量元素地球化学特征值反映曲乃亥花岗闪长岩(体)具富硅、富钾、准铝质-过铝质等特征,属于高钾钙碱性花岗岩;岩石的微量元素地球化学分析显示,富集大离子亲石元素(如Rb、Th、K、U),亏损高场强元素(如Nb、Ta、Ti),在稀土配分图上呈现轻稀土元素富集、重稀土元素亏损的右倾曲线特征;岩石构造环境判别图解反映曲乃亥花岗闪长岩(体)为Ⅰ型花岗岩,属于俯冲环境下活动大陆边缘构造作用所形成的产物,其可能主要来自于地壳物质的部分熔融。
This paper studied petrology,chronology and rock geochemistry of Qunaihai granodiorite in the eastern part of the Gonghe Basin.The LA-ICP-MS zircon U-Pb dating of the granodiorite is 239.4 Ma±2.8 Ma(n=16,MSWD=0.29)indicating that the rock mass was formed in the Middle Triassic Epoch.Major elements of the granodiorite are characteristic of silicon-rich,potassium-rich,metaluminous to weak peraluminous material thus it belongs to high-potassium-calcium-alkaline granite;trace elements characteristic of enrichment of large-ionic lithophile elements(Rb,Th,K,U)and depletion of high-field strength elements(Nb,Ta,Ti)LREE enrichment and HREE depletion pattern.In the geotectonic environment discremination plot it is identified as I-type granite,the product of active continental marginal structural activity under subduction environment derived mainly from partial melting of the crustal material.
作者
孔令添
黎敦朋
张森琦
罗坤
KONG Lingtian;LI Dunpeng;ZHANG Senqi;LUO kun(College of zijin mining,fuzhou university,fuzhou,350108,China;Center for Hydrogeology and Environmental Geology Survey,China Geological Survey,Baoding 071051,Hebei,China)
出处
《地质找矿论丛》
CAS
CSCD
2019年第3期423-431,共9页
Contributions to Geology and Mineral Resources Research
基金
中国地质调查局“青海西宁-贵南地区地热资源调查”项目(编号:DD20179621)资助
