Texture and Geochemistry of Multi-stage Hydrothermal Scheelite in the Mamupu Cu-Au-Mo(-W)Deposit,Eastern Tibet:Implications for Tungsten Mineralization in the Yulong Belt  

作　　者：ZHANG Xiaoxu TANG Juxing LIN Bin WANG Qin HE Liang YAN Gang SHAO Rui WU Qiang DU Qiu ZHAXI Pingcuo 

机构地区：[1]Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610081,China [2]MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [3]SinoProbe Laboratory,Chinese Academy of Geological Sciences,Beijing 100094,China [4]Earth Sciences College,Chengdu University of Technology,Chengdu 610059,China [5]No.6 Geological Party,Tibetan Bureau of Geology and Mineral Exploration and Development,Lhasa 851400,China [6]Tibet Shengyuan Mining Group Co.,Ltd.,Lhasa 851400,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第3期701-716,共16页地质学报（英文版）

基　　金：jointly supported by the National Key Research and Development Program of China(Grant No.2022YFC2905001);the Basic Research Fund of the Chinese Academy of Geological Sciences(Grant No.JKYZD202316);the National Natural Science Foundation of China(Grant Nos.42272093,42230813,42002097);the Research Project of the Shengyuan Mining Co.,Ltd.,Tibet(Grant No.XZSYKYJT-JSFW2019-001);the China Scholarship Council project and the Geological Survey project(Grant Nos.DD20230054,DD20221684,DD20221690,DD20230031,DD20230049,DD20230338)。

摘　　要：Multistage tungsten mineralization was recently discovered in the Mamupu copper-polymetallic deposit in the southern Yulong porphyry copper belt(YPCB),Tibet.This study reports the results of cathodoluminescence,trace element and Sr isotope analyses of Mamupu scheelite samples,undertaken in order to better constrain the mechanism of W mineralization and the sources of the ore-forming fluids.Three different types of scheelite are identified in the Mamupu deposit:scheelite A(Sch A)mainly occurs in breccias during the prograde stage,scheelite B(Sch B)forms in the chlorite-epidote alteration zone in the retrograde stage,while scheelite C(Sch C)occurs in distal quartz sulfide veins.The extremely high Mo content and negative Eu anomaly in Sch A represent high oxygen fugacity in the prograde stage.Compared with ore-related porphyries,Sch A has a similar REE pattern,but with higher ΣREE,more depleted HREE and slightly lower(^(87)Sr/^(86)Sr)i ratios.These features suggest that Sch A is genetically related to ore-related porphyries,but extensive interaction with carbonate surrounding rocks affects the final REE and Sr isotopic composition.Sch B shows dark(Sch B-I)and light(Sch B-II)domains under CL imaging.From Sch B-I to Sch B-II,LREEs are gradually depleted,with MREEs being gradually enriched.Sch C has the highest LREE/HREE ratio,which indicates that it inherited the geochemical characteristics of fluids after the precipitation of HREE-rich minerals,such as diopside and garnet,in the early prograde stage.The Mo content in Sch B and Sch C gradually decreased,indicating that the oxygen fugacity of the fluids changed from oxidative in the early stages to reductive in the later,the turbulent Eu anomaly in Sch B and Sch C indicating that the Eu anomaly in the Mamupu scheelite is not solely controlled by oxygen fugacity.The extensive interaction of magmatic-hydrothermal fluids and carbonate provides the necessary Ca^(2+)for the precipitation of scheelite in the Mamupu deposit.

关 键 词：SCHEELITE GEOCHEMISTRY Mamupu Cu deposit Yulong porphyry copper belt eastern Tibet 

分 类 号：P618.2[天文地球—矿床学]