安徽铜陵焦冲金矿床成矿流体特征及成矿机制

安徽铜陵焦冲金矿床位于长江中下游铁铜金银铅锌成矿带铜陵矿集区内,矿体主要赋存在下二叠统栖霞组(P1_q)灰岩中。根据野外地质特征及含矿组合,将矿床划分为3个成矿阶段:黄铁矿-石英阶段、石英-硫化物阶段和石英-方解石阶段。笔者对该矿床不同成矿阶段石英和方解石进行了详细的岩相学观察和显微测温研究。结果表明,该矿床的均一温度区间分别为410~440 ℃、320~350 ℃和260~320 ℃。显示早期的黄铁矿-石英阶段、石英-硫化物阶段,直到晚期的石英-方解石阶段均一温度呈现逐渐减低的趋势。根据公式计算矿床成矿深度约1.5 km,成矿压力400×10⁵ Pa。流体沸腾作用是金属硫化物大量沉淀的主要机制。

Characteristics of Fluid Inclusions and Primary Metallogenic Mechanism of Jiaochong Au S Deposit in Tongling Area,Anhui

Jiaochong Au S deposit is located in Tongling ore concentration area which is in the middle and lower reach of Yangtze River .The ore bodies are mainly existed in the limestone of Qixia Group in Early Permian . According to the research of the field geological characteristics and ore composition ,Jiaochong ore was fromed in the three phases :early quartz stage ,middle quartz‐sulfide stage , and late calcite stage . Through the detailed petrographic observation and microscopic measurement to the quartz and calcite of different ore‐forming stages , the fluid homogenization temperatures fall into the three scopes :410 440 ℃ ,320 350 ℃ ,and 260 320 ℃ correspondingly , showing a downward trend from the early quartz stage to the late calcite stage .According to the formula calculation ,the metallogenic depth is about 1 .5 km ;and the mineralization pressure is 400 × 105 Pa . Fluid boiling action was the main mechanism of metal sulfides precipitation .Trapping pressures of fluid inclusion are used to estimate the ore‐forming pressure and depths ,so as to provide a theoretical basis for deep prospecting prediction .