The Jiuyishan complex massif,located in the northern section of the Nanling region,is a combination of five plutons,namely,the Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan plutons.Whole-rock geochemistry,Iminer...The Jiuyishan complex massif,located in the northern section of the Nanling region,is a combination of five plutons,namely,the Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan plutons.Whole-rock geochemistry,Imineral electron microprobe analysis,zircon U-Pb dating and Hf isotope analysis were carried out for the Jinjiling and Pangxiemu plutons.The zircon U-Pb dating yields weighted mean ages of 152.9±0.9 Ma for the Jinjiling pluton and 151.7±1.5 Ma for the Pangxiemu pluton,with a narrow gap between them.The Jinjiling and Pangxiemu plutons both have geochemical characteristics of high SiO2,Al2 O3,Na2 O,K2 O and low TiO2,MgO,CaO,P2 O5 contents,with intense depletions in Sr,Ba,Ti,Eu and enrichments in Ga,FeoOT and HFSE,and these characteristics reflect an A-type affinity.From the Jinjiling to the Pangxiemu plutons,the mineral composition of mica changes from lepidomelane to zinnwaldite,with increases in F,Li2 O and Rb2 O contents.The mineral composition of zircon changes from low Zr/Hf to high Zr/Hf,with increasing HfO2,P2 O5 and UO2+ThO2+Y2 O3 contents.The mineral compositions of feldspar indicate that the Pangxiemu pluton contains more alkali feldspar than the Jinjiling pluton.The whole-rock geochemistry and mineral compositions reveal a higher degree of differentiation for the Pangxiemu pluton.The nearly uniformεHf(t)indicates the same source region for the two plutons:both were derived from partial melting of the lower crust,with small contributions of mantle materials.In addition,higher F,lower Nb/Ta and Zr/Hf ratios in the Pangxiemu Pluton suggest a closer relationship with the rare metal mineralization than for the Jinjiling pluton.展开更多
基金financially supported by the Key R&D Program of China(Grant No.2017YFC0602402)the Innovationdriven Plan of Central South University,China(Grant No.2015CX008)+2 种基金the China Postdoctoral Science Foundation(Grant No.2017M622597)Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education(Grant No.2019YSJS23)the Natural Science Foundation of Hunan Province(Grant No.2017JJ3138)
文摘The Jiuyishan complex massif,located in the northern section of the Nanling region,is a combination of five plutons,namely,the Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan plutons.Whole-rock geochemistry,Imineral electron microprobe analysis,zircon U-Pb dating and Hf isotope analysis were carried out for the Jinjiling and Pangxiemu plutons.The zircon U-Pb dating yields weighted mean ages of 152.9±0.9 Ma for the Jinjiling pluton and 151.7±1.5 Ma for the Pangxiemu pluton,with a narrow gap between them.The Jinjiling and Pangxiemu plutons both have geochemical characteristics of high SiO2,Al2 O3,Na2 O,K2 O and low TiO2,MgO,CaO,P2 O5 contents,with intense depletions in Sr,Ba,Ti,Eu and enrichments in Ga,FeoOT and HFSE,and these characteristics reflect an A-type affinity.From the Jinjiling to the Pangxiemu plutons,the mineral composition of mica changes from lepidomelane to zinnwaldite,with increases in F,Li2 O and Rb2 O contents.The mineral composition of zircon changes from low Zr/Hf to high Zr/Hf,with increasing HfO2,P2 O5 and UO2+ThO2+Y2 O3 contents.The mineral compositions of feldspar indicate that the Pangxiemu pluton contains more alkali feldspar than the Jinjiling pluton.The whole-rock geochemistry and mineral compositions reveal a higher degree of differentiation for the Pangxiemu pluton.The nearly uniformεHf(t)indicates the same source region for the two plutons:both were derived from partial melting of the lower crust,with small contributions of mantle materials.In addition,higher F,lower Nb/Ta and Zr/Hf ratios in the Pangxiemu Pluton suggest a closer relationship with the rare metal mineralization than for the Jinjiling pluton.
