Geochemistry and U-Pb geochronology of the granite porphyry in Bainiuchang,Southeastern Yunnan,China  

作　　者：Nan Shi Jun Zhu Xuelong Liu Shitao Zhang Guangzhi Meng Hong Zhang Jialong Cheng Jiehu Zhou Bode Lu Junshan Dao Xue Mi Maohuang Fan 

机构地区：[1]College of Land Resources Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China [2]Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,MNR,Kunming 650051,Yunnan,China [3]Yunnan Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Kunming 650051,Yunnan,China [4]Geological Team 306 of Yunnan Non-Ferrous Metals Geological Bureau,Kunming 650217,Yunnan,China [5]Yunnan Mengzi Mining and Metallurgy Co.,Ltd,Mengzi 661199,Yunnan,China [6]Yunnan Institute of Geology and Mineral Resources Exploration,Kunming 650051,Yunnan,China

出　　处：《Acta Geochimica》2025年第2期325-347,共23页地球化学学报(英文)

基　　金：supported by Yunnan Major Scientific and Technological Project(202202AG050006);National Natural Science Foundation of China(42362010);The Open Fund of Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Ministry of Nature Resources(ZRZYBSJSYS2022002)。

摘　　要：The Bainiuchang Ag-polymetallic ore deposit,located in southeastern Yunnan,China,is one of the region's largest deposits.However,the hyp abyssal granite porphyry within this mining area has yet to be comprehensively investigated.In this study,we conducted geochemical,geochronological,whole-rock Sr-Nd isotope,and zircon Hf isotope analyses on granite porphyry samples collected from the Bainiuchang deposit.The results indicate that the granite porphyry formed between 87.5 and 87.4 Ma in the Late Yanshanian period.Geochemically,the granite is strongly peraluminous,with high silica and alkali contents consistent with S-type granite characteristics.The granite porphyry is enriched in large-ion lithophile elements(Rb,Th,U,and K)and is relatively depleted in Ba and Sr.The initial ^(87)Sr/^(86)Sr ratios are high(0.71392-0.71585),accompanied by low ε_(Nd)(t)values(-8.9 to-8.2).The zircons exhibited similarly low ε_(Hf)(t)values(-9.31 to-3.6).These data suggest that the porphyry-forming magma originated from a continental crustal source.The two-stage Hf and Nd model ages are estimated at 1534-1216 Ma and 1615-1561 Ma,respectively.Thus,the granite porphyry likely formed under a strike-slip extensional setting in the Late Yanshanian period and resulted from the re-melting of Proterozoic basement metagreywackes.This porphyry shares a similar magmatic origin with concealed granite bodies within the deposit and is associated with structural reactivation during the Yanshanian.The findings of this study provide valuable insights into the tectonomagmatic mineralization processes in the B ainiuchang area.

关 键 词：Zircon U-Pb ages GEOCHEMISTRY Sr-Nd isotopes Granite porphyry Bainiuchang silver polymetallic ore deposit Southeastern Yunnan 

分 类 号：P59[天文地球—地球化学]