福建南安四黄角闪辉长岩锆石U-Pb年龄和岩石地球化学特征  

Zircon U-Pb Dating and Geochemical Characteristics of the Sihuang Hornblende Gabbro in Nan'an City,Fujian Province

作　　者：蔡立业 Cai Liye(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》2024年第2期107-118,共12页Geology of Fujian

基　　金：福建省自然资源厅地勘专项“福建1∶5万安溪县、英都、南安市幅区域地质调查”项目。

摘　　要：泉州南安四黄角闪辉长岩LA-ICP-MS锆石U-Pb同位素年龄为(114.7±1.2)Ma,形成于早白垩世中期。岩石富Al2O3、高Na,低Si、低K、低MgO。δEu值为1.00~1.04,无明显的Eu异常,(La/Yb)N值为4.46~6.79,属轻稀土富集型。在原始地幔标准化微量元素蛛网图上,四黄角闪辉长岩总体上显示富集大离子亲石元素和轻稀土元素,高场强元素Nb、Ti、P明显亏损,与活动大陆边缘玄武岩相似,结合微量元素Zr/Sm-Zr、Rb/Nb-Rb/Zr的相关性,表明岩石在侵位过程中分离结晶、堆晶作用明显。四黄角闪辉长岩可能形成于大陆边缘弧伸展构造环境或板内伸展构造环境。The LA-ICP-MS Zircon U-Pb isotopic age of the hornblende gabbro in Sihuang,Nan'an is(114.7±1.2)Ma,which was formed in the middle of early Cretaceous.The rocks are rich in Al2O3,high Na,low Si,low K and low MgO.TheδEu value was 1.00~1.04,and there was no obvlous Eu anomaly.(La/Yb)N value was 4.46~6.79,enrichment of light rare earth elements.On the primitive mantle-standardized trace element spider diagrams,the Sihuang hornblende gabbro generally shows that it is enriched in large ion lithophile elements and light rare earth elements.Intensive depletion in high field strength element Nb,Ti,and P,which is similar to that of active continental margin basalts.In the process of rock placement,the crystallization and crystallization are obvious,which is further proved in the correlation of trace elements Zr/Sm-Zr and Rb/Nb-Rb/Zr.The Sihuang hornblend gabbro may be formed in the continental margin arc extensional environment or intraplate extensional.tectonic environment.

关 键 词：地球化学 U-PB同位素 分离结晶 角闪辉长岩 福建南安 

分 类 号：P597.3[天文地球—地球化学]