Genesis of the Nuri Cu-W-Mo Deposit,Tibet,China:Constraints from in situ Trace Elements and Sr Isotopic Analysis of Scheelite  

作　　者：WANG Yiyun WU Zhishan CHEN Wenqing DU Qing’an TANG Liwei SHI Hongzhao MA Guotao ZHANG Zhi LIANG Wei WU Bo MIAO Hengyi 

机构地区：[1]Chengdu Center,China Geological Survey(Geoscience Innovation Center of Southwest China),Chengdu 610081,China [2]The Second Geological Institute of China’s Metallurgical Geology Bureau,Fuzhou 351111,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第1期117-131,共15页地质学报（英文版）

基　　金：financially supported by the National Key Research and Development Program of China(Grant No.2021YFC2901903);the Geological Comprehensive Research Project of China’s Metallurgical Geology Bureau(Grant No.[2022]CMGBDZYJ005),the National Natural Science Foundation of China(Grant No.42002097);the Geological Investigation Project(Grant Nos.DD20230031,DD20221690,DD20230049,DD20230337).

摘　　要：The Nuri deposit is the only Cu-W-Mo polymetallic deposit with large-scale WO3 resources in the eastern section of the Gangdese metallogenic belt,Tibet,China.However,the genetic type of this deposit has been controversial since its discovery.Based on a study of the geological characteristics of the deposit,this study presents mineralization stages,focusing on the oxide stage and the quartz-sulfide stage where scheelite is mainly formed,referred to as Sch-A and Sch-B,respectively.Through LA-ICP-MS trace element and Sr isotope analyses,the origin,evolutionary process of the oreforming fluid and genesis of the ore deposit are investigated.Scanning Electron Microscope-Cathodoluminescence(SEMCL)observations reveal that Sch-A consists of three generations,with dark gray homogenous Sch-A1 being replaced by relatively lighter and homogeneous Sch-A2 and Sch-A3,with Sch-A2 displaying a gray CL image color with vague and uneven growth bands and Sch-A3 has a light gray CL image color with hardly any growth band.In contrast,Sch-B exhibits a‘core-rim’structure,with the core part(Sch-B1)being dark gray and displaying a uniform growth band,while the rim part(Sch-B2)is light gray and homogeneous.The normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore-forming fluid in the Nuri deposit originated from granodiorite porphyry and,later on,some country rock material was mixed in,due to strong water-rock interaction.Combining the O-H isotope data further indicates that the ore-forming fluid in the Nuri deposit originated from magmatic-hydrothermal sources,with contributions from metamorphic water caused by water-rock interaction during the mineralization process,as well as later meteoric water.The intense water-rock interaction likely played a crucial role in the precipitation of scheelite,leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz-sulfide stage,while also causing a gradual decrease in oxygen fugacity(fO2)and

关 键 词：trace elements in situ Sr isotopes tungsten mineralization Gangdese metallogenic belt TIBET 

分 类 号：P618.2[天文地球—矿床学]