山西义兴寨金矿床金矿物颗粒的产出及其成矿动力学意义

山西义兴寨金矿床的金主要呈包体金和裂隙金两种产出状态.文章根据成矿地球化学动力学理论,论证了金元素在含矿断裂发生脆性破裂和脆-韧性扩张活动中析出的化学反应类型,以及受反应动力学条件的制约,形成矿石中金不同产出状态的规律.指出热液矿床中普遍存在的包体金为热液成矿早期阶段断裂发生脆性破裂和成矿流体沸腾,导致快速反应结晶的产物;而裂隙金和晶隙金为成矿晚期金等矿质在流体中残余富集,同时成矿断裂再次发生脉动破裂,即成矿热力学演化与有利的构造动力学因素耦合作用的结果.得出金矿物颗粒的产出状态具有成矿动力学意义的结论.

Modes of Occurrence of Au_mineral Particles in Yixingzhai Gold Deposit and Their Metallogenic Dynamic Significance

There are two kinds of Au_mineral particles in the Yixingzhai hydrothermal gold deposit of Shanxi Province, namely inclusions in pyrite and mineral grains along fractures. This paper deals with the chemical re_actions leading to the precipitation of the two kinds of gold and the controlling roles played by the tectonic_dy_namic conditions in the ore_forming processes along ore_bearing fractures. The activities of ore_controlling fracture during hydrothermal mineralization can be divided into two stages: brittle splitting stage and brittle_tough tension stage, which created different geodynamic conditions for the metallogenic geochemical thermodynamic system. At the early brittle splitting stage the system was strongly supersaturated and unequilibrated by fluid boiling, which quickened and enhanced the crystallization of ore elements and gold precipitates as "inclusion" form gold in pyrite; at the late brittle_tough tension stage, the ore_forming system was in a weakly supersaturated state, and with the gradual decrease of the temperature and pressure, the crystallization of ore materials became slow and the gold precipitated from residual solution in late tectonic microfractures. It is therefore concluded that the difference in modes of occurrence of Au_mineral particles in ores has metallogenic dynamic significance.