| 云南兰坪北部铜多金属矿化区成矿流体流动与矿化分带——流体包裹体和稳定同位素依据 |
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| 引用本文：.2003.Migration of Ore-forming Fluids and Its Relation to Zoning of Mineralization in Northern Lanping Cu_polymetallic Metallogenic Area, Yunnan Province: Evidence from Fluid Inclusions and Stable Isotopes[J].Mineral Deposits,22(4):365~376 |
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| 基金项目:国家自然科学基金项目(编号：40073014) |
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| 中文摘要:滇西兰坪盆地北部发育了一类受逆冲推覆构造控制的浅成热液Cu-Ag-Pb-Zn矿化，形成了白秧坪、富隆厂、吴底厂、麻栗坪及金满、科登涧等大-中型矿床和矿点，并存在矿化分带。文章利用这些矿化脉体的流体包裹体和热液方解石的碳氧同位素组成资料，研究成矿流体与矿化分带的关系。结果表明，成矿流体主要属于NaCl-H2O成分体系，盐度w(NaCleq)为2%～11%，形成温度为170～300℃，形成于1.8～3.8 km深度内，这些相似性说明这类矿化的发生具有相似的流体性质和沉淀机制。热液方解石在δ13C-δ18O图解中呈近水平线展布的型式，指示流体源自地壳浅部的地下水系统，与海相灰岩等围岩作用形成了溶解碳以［HCO3］-为主的成矿流体，流体与岩石的相互作用可能是成矿流体沉淀的主要机理。从西到东，流体包裹体的盐度_温度由高到低变化与矿化分带和逆冲推覆构造的根带→中带→锋带相配套，显示重力驱动流动可能是主要的流体流动机制。成矿流体在不同构造部位流动的通畅及流体_岩石系统的封闭_开放程度等流体流动性质与矿化发生的强度和规模有关，兰坪北部逆冲推覆构造中带的流体通畅地流动及沉淀时处于相对开放状态，有利于该区形成较大规模的浅成热液多金属矿化。 |
| 中文关键词:地球化学 流体流动 矿化分带 逆冲推覆构造 流体包裹体 稳定同位素 兰坪 |
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| Migration of Ore-forming Fluids and Its Relation to Zoning of Mineralization in Northern Lanping Cu_polymetallic Metallogenic Area, Yunnan Province: Evidence from Fluid Inclusions and Stable Isotopes |
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| Abstract:Controlled by the thrust_nappe structures, a series of epithermal Cu-Ag-Pb-Zn mi neralizations occur in northern Lanping basin, western Yunnan, thus forming a la rge number of polymetallic deposits, such as Baiyangping, Fulongchang, Wudichang , Maliping, Jinman and Kedengjian, with the existence of mineralization zoning i n the region. The fluid inclusion and C_O isotope data from 13 ore veins were us ed to study the relationship between the ore_forming fluids and the zoning of mi neralizations. It is shown that 2_phase liquid_rich aqueous inclusions and singl e_phase liquid aqueous inclusions are most commonly seen, together with a few 3-phase solid-bearing aqueous inclusions and 3-phase CO2-aqueous inclusions. The 2-phase liquid-rich aqueous inclusions belong to the NaCl-H2O system, with sa linity, trapping temperature and formation depth of 2-11 eq. wt% NaCl, 170～300 ℃ and 1.8～3.8 km, respectively. Therefore, there existed similar fluid charact eristics and precipitation mechanism in these mineralizations. The δ13C a nd δ18O values of hydrothermal calcites fall within the ranges of -6.6‰ ～2.11‰ PDB and 6.46‰～17.05‰ SMOW, respectively. Nearly horizontal correlati on array of C-O isotopes from hydrothermal calcites implies that the fluids came from the underground water system in the shallow part and that ［HCO3］- wa s the dominant form of dissolved carbon in the fluids. From the west to the east of the basin the salinity and homogenization temperature of fluid inclusions gr adually decrease, which is in consistent with the zoning of the mineralizations and the thrust_nappe structures (root zone→median zone→frontal zone), suggesti ng that the gravity-driven fluid migration might have acted as the major fluid f low model in this area. The continuous flow of fluids and the close_open degree in the interaction between the fluids and the wall rocks along the fault system are associated with the intensity and scale of the polymetallic mineralizations. The continuous flow and the good open state are favourable to the large-scale m ineralization in the median zone of Lanping thrust_nappe structures. |
| keywords:geochemistry, fluid flow, zoning of mineralization, thrust-nappe structure, fluid inclusion,stable isotope, Lanping |
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