河南桐柏老湾金矿床地质特征及成因探讨   总被引：5，自引：0，他引：5  

张宗恒  方国松  侯海燕  马宏卫  侯万荣 《黄金地质》2002,8(3):20-26

老湾金矿属剪切带型金矿床，矿体的分布受Riedel剪切裂隙系统控制，成矿流体具低盐度，弱碱性及较高矿化度的混合水特点，区内的龟山岩组是原始矿源层，燕山期老湾花岗岩提供了部分热源，水源及成矿物质，Au主要是以Au-S,Au-Si配合物形式迁移，其次是被硅胶吸附呈胶体状态迁移，而成矿流体的温度，压力,pH值降低，氧化还原电位的改变和电解质加入引起的凝胶作用是导致Au沉淀的重要因素。  相似文献   

河南老湾金矿床成矿流体性质与同位素地球化学示踪     

陈加伟  孙保平  李佩  裴满意  任强 《岩石矿物学杂志》2017,36(5):713-724

老湾金矿床是河南桐柏地区典型的剪切带型金矿床。流体包裹体特征显示成矿流体为中低温、低盐度的含CO_2的K~+-Na~+-Cl~-SO_4~(2-)体系;氢氧同位素研究结果显示矿床成矿早期阶段以岩浆水为主要成矿热液来源,成矿晚期阶段以大气降水为主要热液来源:矿石铅同位素特征显示成矿物质源区与龟山岩组、老湾花岗岩有亲缘关系,且与花岗岩接近,显示其深源特征,进一步提供了成矿流体岩浆成因的证据。  相似文献   

Recognition of Yanshanian magmatic-hydrothermal gold and polymetallic gold mineralization in the Laowan gold metallogenic belt,Tongbai Mountains: New evidence from structural controls,geochronology and geochemistry     

《Ore Geology Reviews》2015

The Laowan metallogenic belt in China is an important metallogenic belt within the Tongbai orogenic belt, and contains the medium-sized Laowan and Shangshanghe gold deposits, the small Huangzhuyuan lead–zinc–silver–gold deposit and some gold and Cu–Pb occurrences. These deposits are hosted in Mesoproterozoic plagioclase amphibolite (or schist) and mica-quartz schist. The gold ores are mainly quartz veins and veinlets and disseminated altered ores. Subordinate ore types include massive sulfides and breccias. The Laowan gold deposit is characterized by three right-stepping en-echelon fracture-controlled alteration zones that dip gently to the south and includes disseminated, sheeted and stockwork ores. These lodes were formed by the interaction of ore-forming fluid with foliated-to laminated cataclasite within the transpressional faults. The Shangshanghe gold deposit is characterized by parallel ore lodes that dip steeply to the north, and includes quartz veins and breccias in addition to ores in altered wallrocks. These lodes were formed by focusing of fluids into transtensional faults. These ore controlling faults displaced early barren quartz veins 10 m horizontally with a dextral sense of motion. The ore-hosting structures at the Laowan and Shangshanghe deposits correspond to the P and R-type shears of a brittle dextral strike-slip fault system, respectively, which make angles of about 15° and − 15° to the Laowan and Songpa boundary faults. The ore-controlling fault system post-dated formation of a ductile shear zone, and peak regional metamorphism. This precludes a genetic relationship between hydrothermal mineralization and regional metamorphism and ductile shear deformation. These gold deposits are not typical orogenic gold deposits. The metallogenic belt displays district-scale-zoning of Mo → Cu–Pb–Zn–Ag → Au relative to Songpa granite porphyry dike zone, suggesting the mineralization may be closely related to the granite porphyry. Measured δ³⁴S of sulfides and δ¹⁸O and δD of fluid inclusion waters in auriferous quartz also are consistent with a magmatic source for sulfur and ore fluids. The similarity of Pb isotope ratios between the ores and Yanshanian granitoids suggests a similar source. As the age (139 ± 3 Ma) of granite porphyry obtained by zircon U–Pb isotope overlaps the mineralization age (138 ± 1 Ma: Zhang et al., 2008a), the gold and polymetallic metallogenesis of the Laowan gold belt has close spatial, temporal and possibly genetic relationships with Yanshanian high level magmatism.  相似文献   

On the formation conditions of porphyry Cu-Mo polymetallic deposits in the Xiaosigou district     

Yinhan Chen 《中国地球化学学报》1987,6(2):140-152

The host mass consists of quartz diorite-porphyry (marginal facies), granodiorite porphry (intermediate facies) and granite porphry (central facies). The petrographical facies are asymmetrically spread. The formation temperature of the rock mass ranges from 890 to 800°C, the pressure from 330 to 380 bars and the depth from about 1.5 to 2 km. Mineralization is controlled by the N-E contact zone and adjacent fault structures. Mo-mineralization occurs in the granite porphyry with strong potash metasomatism. Cu-Mo-mineralization is distributed in the inner contact zone of the rock mass, and the wallrock is K-silicified granite porphyry. Cu-pyrite-mineralization is recognized in skarn and serpentinite. Pb-Zn ore veins occur in marbleized limestones. Rock and mineral analyses, fluid inclusion studies and highT-P experiments indicate that extensive precipitation of Cu-bearing pyrite took place atT = 290–250°C, andP = 330–380 bars and that of copper atT = 400–310°C andP = 330–380 bars. Precipitation of Pb and Zn was followed by the transformation of hydrothermal solutions from alkaline to intermediate with decreasing temperature.  相似文献