矿床地质2023，Vol.42Issue(6)：1139-1158,20.DOI:10.16111/j.0258-7106.2023.06.004
江西武山铜矿区新发现钨矿(化)体特征和其成因
Characteristics and genesis of newly discovered W mineralization in Wushan Cu deposit,Jiangxi:Constraints from mineralography,in-situ U-Pb chronology and element geochemistry of scheelite
摘要
Abstract
Although there are obvious differences in geochemical behavior for tungsten and copper in magmatic sys-tems,it is able to find large-scale Cu-and W-mineralization in one ore deposits,and the reasons for this occur-rence are still under-researched.There are representative porphyry-skarn-stratabound Cu(W)deposits in the Mid-dle-Lower Yangtze River metallogenic belt(MLYRMB),and the timing of formation of stratabound Cu(W)ore bodies is not yet precise.In this study,we present mineralography,laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)U-Pb dating and element geochemistry of scheelite,which is newly found in the Wushan Cu-W deposit,located in the Jiurui ore area,a main component of the MLYRMB.Scheelite mineraliza-tion developed among stratabound,skarn and porphyry types copper orebodies.Zoning pattern from shallow to deep is mineralization of Cu transit to Cu-W.The scheelite minerals in the three types of ores are similar charac-terized by filling in the crystal gap of large pyrite grain or distributing in a disseminated form,replaced by chalco-pyrite,sphalerite,and other minerals,and yielded in degenerate alteration stage.There is also a small amount of scheelite yielded in quartz sulfide stage in the granite-type ore,which coexists with quartz and pyrite to form fine veins and cut through granodiorite porphyry.In this timing and geochemistry study to the scheelite of degenerate alteration stage,scheelite grains form stratabound orebody yield U-Pb ages of(140.6±1.5)Ma,representative the timing of Cu-W stratabound ore,and basically consistent with the age of porphyry and skarn-types copper polymetallic ore bodies obtained by predecessors within the error range.The REE patterns and Sr/Mo ratio of scheelite in the stratabound orebody are similar to magmatic hydrothermal tungsten deposits.Stratabound mine-ralized scheelite has obvious lower Mo content than skarn and granite-types,reflecting its more reduced forming environment,it also has positive Eu anomaly,and high Y/Ho ratio which is similar to wall rock.It is infered that the magmatic fluid had been enough replaced by the carbonaceous wall rock stratum,leading to apparent changes in fluid properties,and being more conducive to the deposition of scheelite and pyrite,thus forming pyrite ore with higher W grade in the stratabound part of Huanglong Formation at the depth of the deposit.This study con-firms that Cu-W stratabound orebody is an important part of porphyry-skarn metallogenic system.Proposing the generally zoning pattern of shallow copper and deep tungsten in the Jiurui ore area,can help to W exploration strategies which should focus on the deep part of known copper ore,especially the coupling of Yanshanian inter-mediate-acid intrusive rock and carbonaceous carbonate rock,and Carboniferous Huanglong Formation.The U-Pb isotope dating of scheelite provides a new and reliable evidence for the age of stratabound orebodies in the MLYRMB.关键词
白钨矿U-Pb年龄/层状矿体/武山矿床/长江中下游成矿带Key words
scheelite U-Pb age/stratabound orebody/Wushan deposit/Middle-Lower Yangtze River Metallo-genic Belt(MLYRMB)分类
天文与地球科学引用本文复制引用
高任,谢桂青,冯道水,纪云昊,钟浩,张磊..江西武山铜矿区新发现钨矿(化)体特征和其成因[J].矿床地质,2023,42(6):1139-1158,20.基金项目
本文得到国家自然科学基金项目(编号:41925011)、江西省科学技术厅国家科技奖后备项目培育计划(编号:20203AEI91004)和江西省地质勘查基金项目(编号:20200022)联合资助 （编号:41925011）
