Geochemistry,Zircon U-Pb Dating and Hf Isotope Composition of Granite in Fanshan Area,Pinghe County,Fujian Province,and Its Geological Significance
Wang Sen
Zhang Da?
Zhao Hongsong
Pan Tianwang
Lü Liangji
Feng Haibin
Di Yongjun
Abstract：In order to study the chronological and geochemical characteristics of the Mesozoic granite and granodiorite from Fan-shan area and their relationship with the regional mineralization,the LA-MC-ICPMS zircons U-Pb dating method was employed to assess the ages and Hf isotope composition,preceded by their petrological and geochemical studies.In addition,the authors aim to provide more evidences that will facilitate the next phase of prospecting by making a comparison with Zijinshan copper-gold ore field.The metaluminous-peraluminous high-K calcalkaline granite series and granodiorite are characterized by high con-tents of K2 O,SiO 2 ,and low TiO 2 .These samples are enriched in light rare earth element (LREE)and large ionic lithophile elements (LILE,e.g.K,Rb,Sr,Cs),but depleted in high strength elements (HFSE,e.g.Nb,Ta,Zr,Ti),and have nega-tive Eu anomalies.The geochemical properties of granite and granodiorite are similar to those of the magmatic arc rocks,which suggest a backarc spreading setting.The zircon U-Pb dating of two representative samples yield an emplaced age of 1 10 Ma,in Early Cretaceous.Zircon grains from the granites have lower Hf-isotpe compositions withεHf (t )=-3.1-1.6 and younger Hf model ages (T DM2 )=1 066-1 366 Ma.In comparison with the metamorphic basement near the study area,we suggest that the granitic rocks are probably derived from a Mesoproterozoic crust,but the granodiorite may have originated from a Mesoprot-erozoic crust-mixed with a fraction of mantle materials.Based on the comparative study with Zijinishan Orefield,it is concluded that there are similar structural,lithogeneous and metallogenic features between the two areas,and there is huge prospecting potential to find “Zijinshan style”copper-gold polymetallic deposits in Fanshan area.
Keywords：Fanshanzircon U-Pb datingHf isotopeZijinshanpetrology
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：17( 67-83 )