Trace Elements of Multi-stage Minerals and Titanite U-Pb Dating for the Gneisses from Liansan Island,Sulu UHPM Belt  

作　　者：SONG Lihao CAO Yuting XIE Tianhe CHEN Yuyao GAO Yuan WANG Songjie LI Xuping 

机构地区：[1]Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Minerals,College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第6期1640-1656,共17页地质学报（英文版）

基　　金：supported by funds from the National Natural Science Foundation of China(Grant Nos.42172067,41972064,U1906207);the SDUST Research Fund。

摘　　要：Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets are distinguished:metamorphic garnet,peritectic garnet and anatectic garnet,which are formed in the stages of peak metamorphism,retrograde anatexis and melt crystallization,respectively.The euhedral titanite has a high content of REE and high Th/U ratios,which is interpreted as indicating that it was newly-formed from an anatectic melt.The LA-ICP-MS titanite U-Pb dating yields 214-217 Ma ages for the titanite(melt)crystallization.The distribution of trace elements varies in response to the different host minerals at different stages.At the peak metamorphic stage,Y and HREE are mainly hosted by garnet,Ba and Rb by phengite,Sr,Nb,Ta,Pb,Th,U and LREE by allanite and Y,U and HREE by zircon.During partial melting,Y,Pb,Th,U and REE are released into the melt,which causes a dramatic decline of these element contents in the retrograde minerals.Finally,titanite absorbs most of the Nb,U,LREE and HREE from the melt.Therefore,the different stages of metamorphism have different mineral assemblages,which host different trace elements.

关 键 词：partial melting multi-stage minerals trace element migration titanite U-Pb dating Sulu UHPM belt 

分 类 号：P588.345[天文地球—岩石学] P597.3[天文地球—地质学]