Geochronology,Geochemistry and Petrogenesis of the Bangbule Quartz Porphyry:Implications for Metallogenesis  

作　　者：HE Chuankai WANG Yong WANG Haiyong TANG Juxing YAN Penggang WANG Yongqiang FU Xuelian FENG Yipeng 

机构地区：[1]College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China [2]MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China [3]No.6 Geological Party,Tibet Bureau of Geology and Mineral Exploration and Development,Lhasa 851400,China [4]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第3期744-758,共15页地质学报（英文版）

基　　金：jointly supported by National Key Research and Development Program of China(Grant No.2022YFC2905002);Special Scientific Research Fund of Tibet Bureau of Geology and Mineral Exploration and Development(Grant No.202119);National Natural Science Foundation of China(Grant No.41902101);Research Start-up Fund of Chengdu University of Technology(Grant No.10912-KYQD2020-08395);the Opening Foundation of MNR Key Laboratory of Metallogeny and Mineral Assessment(Grant No.ZS2101)。

摘　　要：The Bangbule skarn lead-zinc(Pb-Zn)deposit(>1 Mt Zn+Pb)is located in the western Nyainqentanglha polymetallic metallogenetic belt,central Tibet.Lenticular orebodies are all hosted in skarn and developed in the contact zone between the quartz porphyry and carbonate strata of the mid Paleozoic Middle to Upper Chaguoluoma Formation as well as in carbonate and sandstone beds of the Upper Paleozoic Laga Formation.As a newly discovered skarn deposit,the geological background and metallogenesis of this deposit remain poorly understood.Detailed petrological,geochemical and geochronological data of the ore-related quartz porphyry,helps constrain the mineralization age and contributes to discussion on the ore genesis of the Bangbule deposit.Both endoskarn and exoskarn are identified in the Bangbule deposit.From quartz porphyry to carbonate formation,the exoskarn is zoned from proximal garnet skarn to distal pyroxene skarn.Zircon U-Pb dating results show that the quartz porphyry formed at 73.9±0.8 Ma.Geochemical analysis results show that the quartz porphyry has high contents of SiO_(2)(71.40–74.94 wt%)and K_(2)O+Na_(2)O(3.76–8.46 wt%)with A/CNK values of 0.69 to 1.06.Besides,the quartz porphyry is enriched in large ion lithophile elements(LILEs)and light rare earth elements(LREEs)and have lowεNd(t)(from-8.25 to-8.19)and high initial(^(87)Sr/^(86)Sr)i values(0.713611–0.714478).Major,trace elements and whole-rock F concentration analysis results from the endoskarn samples show higher TFe_(2)O_(3),MgO,CaO,Pb+Zn,W,Sn,Mo and F etc.,and lower alkalis(K_(2)O,Na_(2)O,Sr and Ba)than those of fresh quartz porphyry,indicating that the early ore-forming fluids were an Ca-Fe-F-enriched fluid.Massive ore in the proximal skarn might be related to the high F content in the magma,which lowered the solidus temperature of the quartz porphyry magma and caused a lower temperature of the ore-forming fluids,as well as facilitating the precipitation of sphalerite and galena.Based on the geochemical characteristics presented in this study,

关 键 词：PETROGENESIS quartz porphyry METALLOGENESIS Bangbule skarn deposit TIBET 

分 类 号：P618.4[天文地球—矿床学]