福建浦城仙阳地区中生代火山岩锆石U-Pb年龄和地球化学特征  

Geochemical Characteristics and Zircon U-Pb Age of Xianyang Mesozoic volcanics in Pucheng County,Fujian Province

作　　者：李常萌 Li Changmeng(Northern Fujian Geologic Party of Fujian Province,Shaowu,354000)

机构地区：[1]福建省闽北地质大队,邵武354000

出　　处：《福建地质》2022年第1期38-50,共13页Geology of Fujian

基　　金：中国地质调查局基础地质调查项目,“福建1∶5万仙阳、浦城县幅区域地质调查”。

摘　　要：通过对福建浦城仙阳地区中生代火山岩开展详细的锆石U-Pb年代学及地球化学测试工作,新获得3组LA-ICP-MS锆石U-Pb同位素测年值分别为(153.6±2.4)Ma、(160.4±1.9)Ma、(164.1±2.7)Ma,时代属晚侏罗世。火山岩主量元素特征显示属高钾钙碱性系列,微量元素Sr、P、Ti亏损,^(87)Sr/^(86)Sr初始值具有壳源或亏损幔源特征;δEu值为0.24~0.81,平均值为0.56,Eu具弱-中等亏损,火山岩球粒陨石标准化稀土元素配分图曲线与上地壳的趋势曲线大致相同。总体显示区内火山岩形成原始岩浆的熔融体来自地壳及上地幔部分熔融的壳幔混源型岩浆,形成环境为中生代活动的大陆边缘构造环境。Based on the detailed zircon U-Pb geochronology and geochemistry of the Mesozoic volcanic rocks in Xianyang area of Pucheng,Zhejiang and Fujian,we obtained three groups of La-ICP-MS Zircon U-Pb isotopic dating values of(153.6±2.4)Ma,(160.4±1.9)Ma and(164.1±2.7)Ma,respectively.The age belongs to late Jurassic.The petrogeochemistry of volcanic rocks belongs to high k calc-alkaline series,loss of trace elements Sr,P and Ti.The initial value of^(87)Sr/^(86)Sr has shell or loss mantle source characteristics.δEu values range from 0.24 to 0.81,with an average value of 0.56,and Eu has a weak to moderate deficit.The normalized ree distribution curves of volcanic chondrites are roughly the same as the trend curves of the upper crust.As a whole,it shows that the volcanic rocks in the area were formed from the crust and upper mantle partially melted crust-mantle mixed magma,and the formation environment was the continental margin tectonic environment of Mesozoic activity.

关 键 词：中生代火山岩 锆石U-PB年龄 地球化学特征 浦城仙阳 

分 类 号：P534.5[天文地球—古生物学与地层学] P588.14[天文地球—地质学] P597.3