热液中铅、锌、银共生分异的热力学探讨

通过元素基本性质的对比以及热力学计算分析，探讨了热液中银、铅、锌的共生分异机制。在酸性至近中性条件下，氯配合物是它们在热液中的存在形式，其中锌氯配合物最稳定；在近中性到碱性条件下，硫氢配合物占主导地位，此时，银硫氢配合物相对最稳定。温度下降、Cr]降低、pH升高及f(O2)降低，引起银、铅、锌配合物溶解度减小，发生沉淀分离；对于硫氢配合物，其稳定性主要受pH及还原硫浓度的影响。因此，配合物的不同存在形式以及配合物稳定性之间的差异，使得它们对热液条件的改变做出不同的响应，从而导致了热液中银、铅、锌在成矿过程中的共生分异。

A THERMODYNAMIC STUDY ON PARAGENESIS AND SEPARATION OF SILVER,LEAD AND ZINCIN HYDROTHERMAL SOLUTIONS

On the basis of the comparison of basic properties and thermodynamic calculation, the mechanism of paragenesis and separation of silver, lead and zinc in the hydrothermal system has been studied. Under acidic to nearly neutral pH conditions, their chloride complexes are stable, and among them chloride complexes of zinc are most stable. Sulfide complexes are the dominant species under nearly neutral to alkaline pH conditions, while the sulfide complexes of silver are most stable. With decreasing temperature, (Cl~-]), f(O_2) and increasing pH, the solubilities of silver, lead and zinc will decrease, leading to their deposition and separation. For sulfide complexes, the concentrations of reduced sulfur and pH are two important factors, affecting their stabilities. Differences in form and stability of the complexes respond to the variation of thermodynamic conditions to different extent, which resulted in the paragenisis and separation of silver, lead and zinc in the whole ore-forming process of dissolution, transport and deposition.