Zircon U-Pb Dating and Geochemical Characteristics of the Sihuang Hornblende Gabbro in Nan'an City,Fujian Province
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 A12O3,high Na,low Si,low K and low MgO.The δEu value was 1.00～1.04,and there was no obvious 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.
geochemistryU-Pb isotopicfractional crystal lizationhornblend gabbroNan'an City of Fujian
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