闽浙赣交界地区早白垩世火山岩年代学、地球化学及地质意义  

Geochronology,Geochemistry and Geological Significance of Early Cretaceous Volcanic Rocks in the Border Area of Fujian,Zhejiang and Jiangxi Province

作　　者：陈中央 Chen Zhongyang(Fujian Institute of Geological Survey,Fuzhou,350013)

机构地区：[1]福建省地质调查研究院,福州350013

出　　处：《福建地质》2022年第3期188-199,共12页Geology of Fujian

基　　金：中国地质调查局基础地质调查项目,“福建1∶5万二十八都、官路幅区域地质调查”。

摘　　要：闽浙赣交界是东南沿海晚中生代火山岩中研究较薄弱地区,通过对该区下渡组火山岩的野外调查、锆石U-Pb年代学研究、岩石地球化学分析,探讨其成因及构造环境。获得下渡组火山岩LA-ICP-MS锆石U-Pb年龄分别为(133.8±1.0)Ma和(133.24±0.93)Ma,为早白垩世;岩石具高硅、富碱,低铝、钙、镁、铁的特征,铝饱和指数A/CNK均值为1.15,属高钾钙碱性系列弱过铝质酸性火山岩;富集Rb、Pb、Th、U,亏损Sr、Ba、Ti、Nb、Ta等,具有高的10000Ga/Al比值(2.81~3.68),稀土元素含量总量高,呈右倾的“海鸥”型REE配分模式,表明其岩浆来源可能为A型花岗岩。It is a weak area in the study of Late Mesozoic volcanic rocks in the southeast coastal area between Fujian,Zhejiang and Jiangxi Province.Based on the field investigation,zircon UPb chronology and rock geochemical analysis of the volcanic rocks of Xiadu formation in this area,the genesis and tectonic environment of the volcanic rocks are discussed in this area.The zircon U-Pb ages of LA-ICP-MS are(133.8±1.0)Ma and(133.24±0.93)Ma,respectively,indicating early Cretaceous.The volcanic rocks are high silicon(71.87%~76.35%),high alkali(6.89%~9.3%),low in Al,Ca,Mg and Fe.The average value of aluminum saturation index(A/CNK)is 1.15,which belonging to weak peraluminous volcanic rocks of high potassium calc alkaline series;It enriches Rb,Pb,th and U,loses Sr,Ba,Ti,Nb and Ta,has a high 10000Ga/Al value(2.81~3.68),has a high total content of rare earth elements showing a right-leaning seagull type REE distribution pattern indicating that the magma source may be A-type granite.

关 键 词：锆石U-PB定年 地球化学 早白垩世火山岩 闽浙赣 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.14[天文地球—地质学]