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云南个旧卡房铜多金属矿床流体包裹体特征及其地质意义

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卡房铜多金属矿床位于云南省个旧锡多金属矿集区,作为该区南段典型的铜多金属矿床,其深入的成矿流体性质及成矿物质来源研究尚为薄弱,限制了对该矿床成因的深入认识.本文对产于玄武岩中的似层状铜多金属矿体(主要成矿类型)开展了精细的野外岩相学、矿物学、C-H-O 同位素及流体包裹体原位成分分析.结果显示,流体包裹体主要为气液两相水溶液包裹体,石英流体包裹体均一温度为264.5～330.5℃、盐度w(NaCleq)为 16.24%～18.20%、密度为 0.853～0.924 g/cm3;萤石流体包裹体均一温度为199.8～339.1℃、盐度w(NaCleq)为 8.81%～18.88%、密度为 0.822～0.955 g/cm3;方解石流体包裹体均一温度为 112.1～199.4℃、盐度w(NaCleq)为 4.96%～10.86%、密度为 0.910～1.011 g/cm3,表明卡房铜多金属矿床成矿流体具有中低温、中低盐度、低密度特征,且早阶段到晚阶段,成矿温度和流体盐度明显降低.与Cu矿共生的石英 δDV-SMOW值为-83.9‰～-78.9‰,δ18OH2O值为 4.63‰～12.14‰,方解石 δ13CV-PDB值为-7.11‰～0.64‰;同时,石英单个流体包裹体原位分析结果显示流体包裹体富集大离子亲石元素,如Na、K、Rb、Cs、Sr 等.这些特征暗示了流体可能来源于与花岗质岩浆有关的热液流体,热液流体上升过程中与围岩碳酸盐岩发生强烈的水-岩反应;该过程可能萃取了玄武岩层中的Cu物质,诱发了Cu的富集并最终成矿.
Fluid Inclusion Features and Applications of the Kafang Cu-polymetallic Deposit in Gejiu District,Yunnan Province
The Kafang deposit,located in the Gejiu polymetallic district in Yunnan Province,is a typical Cu-polymetallic deposit.Systematical research on the nature of ore forming fluids and origin of the metal is constrained,limiting our understanding of the ore formation in this deposit.In this study,detailed field petrography,mineralogy,C-H-O isotopes,and in-situ composition analysis of fluid inclusions were carried out for the layered Cu-polymetallic ore bodies(the main metallogenic type)which produced in basalt.The results show that the fluid inclusions had mainly gas-liquid biphasic characteristics.The homogenization temperature of quartz fluid inclusions varied from 264.5-330.5℃,the salinaty w(NaCleq)varied from 16.24%to 18.20%and the density varied from 0.853 to 0.924 g/cm3.The homogenization temperature of fluorite fluid inclusions varied from 199.8 to 339.1℃,the salinaty w(NaCleq)varied from 8.81%to 18.88%and the density varied from 0.822 to 0.955 g/cm3.The homogenization temperature of calcite fluid inclusions varied from 112.1 to 199.4℃,the salinaty w(NaCleq)varied from 4.96%to 10.86%and the density varied from 0.910 to 1.011 g/cm3.These parameters collectivelly indicate that the ore-forming fluid of the Kafang Cu-polymetallic deposit was characteries by medium-low temperature,medium-low salinity and low density.Thers is a notable decrease in metallogenic temperature and fluid salinity from the early to the late stages of ore formation.The δDV-SMOW and δ18OH2O values of quartz associated with Cu ore are-83.9‰--78.9‰ and 4.63‰-12.14‰,respectively.The δ13CV-PDB values of calcite associated with Cu ore are-7.11‰-0.64‰.Cuncurrently,in-situ analyses of single fluid inclusions within quartz indicate an enrichment in large ion lithophile elements,such as Na,K,Rb,Cs,Sr.These features suggest that the fluid may be derived from hydrothermal fluids related to granitic magma.Additionally,there is evidence of an intense water-rock reaction between hydrothermal fluids and the surrounding strata of carbonatite strata during ascent,protentially facilitating the extraction of Cu from the basalt and consequently contributing to enrichment and mineralization of Cu.

ore-forming fluidfluid inclusionC-H-O isotopic compositionKafang depositGejiu mining area

李芬、安鹏、肖述刚、孔志岗、余博、闫阔、刘聿栋

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昆明理工大学国土资源工程学院,云南昆明 650093

云南省有色地质局三 0 八队,云南昆明 650214

成矿流体 流体包裹体 C-H-O同位素 卡房矿床 个旧矿集区

云南省科技计划项目企业基础研究应用基础研究联合专项云南省科技计划项目云南省科技计划项目高层次科技人才及创新团队选拔专项Science and Technology Plan Project of Yunnan ProvinceScience and Technology Plan Project of Yunnan ProvinceScience and Technology Plan Project of Yunnan Province

202101BC070001202202AG050006202305AT350004202101BC070001-003202202AG050006-5202305AT350004-5

2024

10.3975/cagsb.2024.043001

地球学报
中国地质科学院

地球学报

CSTPCD北大核心
影响因子：1.797
ISSN：1006-3021
年,卷(期)：2024.45(4)