安徽庐枞盆地枞阳地区玄武质火山岩地球化学特征及其地质意义  

Geochemical characteristics and geological significance of the basaltic volcanic rocks in the Zongyang area of Luzong Basin, Anhui Province

作　　者：杜玉雕[1] 魏国辉[1] DU Yu-diao;WEI Guo-hui(Geological Survey of Anhui Province,Hefei 230001,China)

机构地区：[1]安徽省地质调查院

出　　处：《华东地质》2019年第3期188-198,共11页East China Geology

基　　金：中国地质调查局“安徽庐江矾山-枞阳周潭地区深部找矿靶区验证与评价(编号:12120114012701)”项目资助

摘　　要：庐枞盆地是长江中下游成矿带重要的矿集区之一,枞阳地区玄武质火山岩位于庐枞盆地中部。通过对枞阳地区玄武质火山岩进行岩石地球化学特征研究,探讨其源区性质及玄武质岩浆的演化过程。该区玄武质火山岩贫硅、富碱、低钛、低Mg#值,属于钾玄质系列岩石;稀土元素总量较高,具有LREE富集的右倾型稀土元素配分模式,有较弱的负Eu异常;岩石富集Rb、K、Sr等大离子亲石元素,亏损Nb、Ta、Zr、Hf等高场强元素,Nb、Ta负异常。在岩石圈拉张作用下,枞阳地区富集岩石圈地幔发生部分熔融,形成的玄武质原始岩浆经历了地壳混染和分离结晶作用,沿区域深大断裂上侵,快速上升至地表,形成玄武质火山岩。Basaltic volcanic rocks in the Zongyang area occur in the middle part of the the Luzong(Lujiang-Zongyang)Basin,which is one of the important ore cluster regions in the Middle-Lower Yangtze metallogenic belt.Lithogeochemical study of basaltic volcanic rocks in the Zongyang area has been carried out in order to understand their sources and petrogenetic process.The basaltic volcanic rocks are low in Si,Ti,and Mg#,and high in alkali,suggesting that the rocks belong to shoshonitic rock series.The rocks are characterized by high total rare-earth elements(REE)contents,right-inclined chrondrite-normalized REE patterns,weak negative Eu anomalies;high LILEs(such as Rb,K and Sr)relatively to HFSEs(such as Nb,Ta,Zr and Hf),as well as the distinct negative Nb and Ta anomalies.This study suggests that the original basaltic magma was formed by partial melting of enriched lithospheric mantle at an extensional setting and experienced weak fractional crystallization and crust contamination,and ascended along deep fault and erupted to the surface rapidly and formed the basaltic volcanic rocks.

关 键 词：庐枞盆地 地球化学 玄武质火山岩 源区特征 安徽枞阳 

分 类 号：P597.3[天文地球—地球化学] P588.122[天文地球—地质学]