湖北省铜山口铜(钼)矿床成矿流体水岩反应数值模拟

湖北省铜山口铜(钼)矿床是一典型的夕卡岩 斑岩复合型矿床。通过对其流体包裹体的系统研究,确定了成矿流体的成分及温压条件;结合矿床学的研究,将成矿过程分解为两个平行的成矿阶段,即夕卡岩型矿化阶段和斑岩型矿化阶段。根据Johnson和Reed等人建立的水 岩反应模型,对该矿床的成矿流体与围岩的反应并析出金属沉淀的过程进行了数值模拟计算。结果表明:在斑岩型矿化阶段,成矿流体系统出现等焓减压沸腾过程并沉淀出大量的金属矿物,成矿流体分异为低盐度流体和高盐度流体;在夕卡岩型成矿阶段,沉淀出典型的夕卡岩矿物;在整个成矿过程中,成矿流体的pH值逐渐升高。模拟计算结果与实际地质现象非常吻合,说明所建立的水 岩反应模型可以为理解这一类复合型金属热液矿床的形成机制提供一个新的思路。

NUMERICAL MODELING ON WATER-ROCK INTERACTION OF MINERALIZATION FLUID OF TONGSHANKOU Cu(Mo) DEPOSIT,HUBEI PROVINCE

Tongshankou Cu(Mo) deposit is a typical skarn porphyry compound deposit. The components, temperature and pressure of the mineralization fluid are determined according to systematic research on the fluid inclusions. Combined with the deposit geology, the mineralization process was divided into two synchronous mineralization stages, the skarn mineralization stage and the porphyry mineralization stage. Via the equibrium model of water rock interaction founded by Johnson and Reed et al., the paper sets up a geochemicial model of the interaction between mineralization fluids and wall rocks with convincing simulating results which are coincident with the factual geological phenomena. These results indicate that during the porphyry type mineralization stage large quantity of metal minerals deposited and iso enthalpy pressure decreasing boiling process emerged and the mineralization fluids evolved into low salinity and high salinity fluids; during skarn type mineralization stage, the typical skarn type minerals formed and during the whole mineralization process the pH increased gradually. It means that the water rock interaction model can provide a new perspective for understanding the metallogenetic mechanism of such a compound metallic hydrothermal deposit.