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
投稿时间:2024-01-02  修订日期:2024-03-08  点此下载全文
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作者单位邮编
李芬 昆明理工大学 650093
安鹏 昆明理工大学 
肖述刚* 云南省有色地质局三0八队 
孔志岗 昆明理工大学 
余博 昆明理工大学 
闫阔 昆明理工大学 
刘聿栋 昆明理工大学 
基金项目: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(编号:202101BC070001-003)、云南省重大科技专项昆明理工大学“双一流”科技专项(编号:202202AG050006)和云南省高层次科技人才及创新团队选拔专项(202305AT350004-5)
中文摘要: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ω(NaCleq)为16.24~18.2%、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ω(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ω(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。
中文关键词:成矿流体  流体包裹体  C–H–O同位素  卡房矿床  个旧矿集区
 
Fluid Inclusion Features and its applications of the Kafang Cu-polymetallic Deposit, in Gejiu district, Yunnan Province
Abstract:The Kafang deposit, located in the Gejiu polymetallic district in Yunnan province, is a typical Cu-polymetallic deposit. The systematical research on the nature of ore forming fluids and origin of the metal is still not well constrained, which limit the understanding of the ore formation in this deposit. In this paper, detailed field petrography, mineralogy, C–H–O isotope 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 are mainly gas-liquid biphasic characteristics. The homogenization temperature of quartz fluid inclusions varied from 264.5~330.5℃, the salinaty ω(NaCleq) varied from 16.24~18.2% and the density varied from 0.853~0.924 g/cm3. The homogenization temperature of fluorite fluid inclusions varied from 199.8~339.1℃, the salinaty ω(NaCleq) varied from 8.81~18.88% and the density varied from 0.822~0.955 g/cm3. The homogenization temperature of calcite fluid inclusions varied from 112.1~199.4℃, the salinaty ω(NaCleq) varied from 4.96~10.86% and the density varied from 0.910~1.011 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 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.
keywords:ore-forming fluid  fluid inclusion  C–H–O isotopic composition  Kafang deposit  Gejiu mining area
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