广西平南新坪金矿成矿流体特征及矿床成因初探

广西新坪金矿地处大瑶山多金属成矿带六岑矿田，矿体主要受新坪复式背斜和近东西向的断裂破碎带控制，赋存于寒武系黄洞口组砂岩、砂泥岩中。石英流体包裹体数据显示，成矿流体为中温低盐度低密度含CO₂的流体；流体中阳离子以Na⁺、Ca²⁺、Mg²⁺、K⁺为主，阴离子以Cl^-为主。氢氧同位素分析表明，成矿流体中水可能主要来源于岩浆，并叠加有变质水，且不排除有少量大气水加入的特征；矿石硫化物的硫同位素组成范围较窄，多为距离零轴很近的负值，推断可能是深源硫与地层硫的混合。根据本次分析及结合前人研究表明，Au来源具有多源性，主要来源于寒武系地层，但区内深源岩浆岩也有提供Au的可能性。据以上分析，结合前人对该地区矿床成因的研究，初步认为新坪金矿属于变质-岩浆热液叠加成矿。

A Preliminary Discussion on Genesis and Ore-forming Fluid Characteristics of the Xinping Gold Deposit in Pingnan County,Guangxi,China

The Xinping gold deposit is located in the Liucen ore field in Dayaoshan polymetallic mineralization belt. The ore bodies, hosted in the sandstone and mudstone of Cambrian Huangdongkou Formation, are related to the Xinping complicated anticline and fracture zone of EW-trending faults.Fluid inclusions in quartz suggest that ore-forming fluids are moderate temperature, low salinity, low density and contain CO₂. The cations in fluids are Na⁺, Ca²⁺, Mg²⁺ and K⁺, while main anion is Cl^-. The data of hydrogen and oxygen isotopes indicate that the ore-forming fluids are probably derived from magmatic fluids, and superimposed by metamorphic fluids and meteoric water also involved. The sulfur isotope values in sulfides are narrowly ranged negative not far from zero,which infers that sulfur in ore is a mixture of sulfur from deep source and strata. Our study combined with previous research show that Au has multi sources, it mainly sourced from Cambrian strata, but the deep magmatic rocks in the region may also provide some Au. Based on above study, we conclude that the Xinping gold deposit was superimposed mineralization of metamorphism and magmatic-hydrothermal fluids.