Records of Neoproterozoic magmatic activity in the western margin of the Yangtze Block are widely distributed,although considerable debate remains regarding the petrogenesis and tectonic setting of this region.We perf...Records of Neoproterozoic magmatic activity in the western margin of the Yangtze Block are widely distributed,although considerable debate remains regarding the petrogenesis and tectonic setting of this region.We performed zircon U-Pb geochronologic,zircon Hf isotope and whole-rock geochemical analyses on Jinkouhe granite(JKHG)samples from the western margin of the Yangtze Block.The zircon U-Pb dating results show that the age of the JKHG formation is 860±4 Ma(MSWD=0.23).The JKHG is classified as high-K calc-alkaline strongly peraluminous S-type granite,and the samples have positive zirconε_(Hf)(t)values of 3.95 to 5.77.Based on the zirconε_(Hf)(t)values and the geochemical characteristics,we conclude that the JKHG is sourced from the mixture of partial melts of metagraywackes and partial melts of juvenile crust.The geochemical analysis shows that the JKHG has the characteristics of syncollisional granitic magmatism.Integrating previous studies with the regional correlations among magma records in this contribution,we propose that the Shimian-Ebian region was a back-arc basin system along the western margin of the Yangtze Block ca.1070~940 Ma and that the JKHG may be related to the final closure of the back-arc basin.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41672112,41872120,41772115,and 41502114)the funds for the Double First-rate Discipline of Chengdu University of Technology(Grant No.10800-1820102)the China Geological Survey(Grant No.DD20160017).
文摘Records of Neoproterozoic magmatic activity in the western margin of the Yangtze Block are widely distributed,although considerable debate remains regarding the petrogenesis and tectonic setting of this region.We performed zircon U-Pb geochronologic,zircon Hf isotope and whole-rock geochemical analyses on Jinkouhe granite(JKHG)samples from the western margin of the Yangtze Block.The zircon U-Pb dating results show that the age of the JKHG formation is 860±4 Ma(MSWD=0.23).The JKHG is classified as high-K calc-alkaline strongly peraluminous S-type granite,and the samples have positive zirconε_(Hf)(t)values of 3.95 to 5.77.Based on the zirconε_(Hf)(t)values and the geochemical characteristics,we conclude that the JKHG is sourced from the mixture of partial melts of metagraywackes and partial melts of juvenile crust.The geochemical analysis shows that the JKHG has the characteristics of syncollisional granitic magmatism.Integrating previous studies with the regional correlations among magma records in this contribution,we propose that the Shimian-Ebian region was a back-arc basin system along the western margin of the Yangtze Block ca.1070~940 Ma and that the JKHG may be related to the final closure of the back-arc basin.
