Abstract
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 ∑REE,more depleted HREE and slightly lower(87Sr/86Sr)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 Ca2+for the precipitation of scheelite in the Mamupu deposit.
基金项目
国家重点研发计划(2022YFC2905001)
Basic Research Fund of the Chinese Academy of Geological Sciences(JKYZD202316)
国家自然科学基金(42272093)
国家自然科学基金(42230813)
国家自然科学基金(42002097)
Research Project of the Shengyuan Mining Co.,Ltd.,Tibet(XZSYKYJT-JSFW-2019-001)
China Scholarship Council project()
Geological Survey project(DD20230054)
Geological Survey project(DD20221684)
Geological Survey project(DD20221690)
Geological Survey project(DD20230031)
Geological Survey project(DD20230049)
Geological Survey project(DD20230338)
国家科技期刊平台
NSTL
万方数据