热液金矿成矿元素运移和沉淀机理研究综述

Mechanisms of Gold Transportation and Deposition in Hydrothermal Gold Deposits

对热液金矿含金热液的流体来源、金的赋存形式、金的迁移和沉淀机理进行了总结。岩浆热液、大气水及变质热液是含金热液的主要来源。金的迁移过程与金的赋存状态有较为密切的关系。金以热液迁移为主,金在热液中的赋存形式主要为金-硫络合物及金-氯络合物,这其中最为重要的是Au(HS)2-、AuHS以及AuCl2-。但是对火山气体及含金流体包裹体的研究表明,金还可以通过气体的方式迁移,并有可能形成具有经济意义的矿床。金在气体中的主要赋存形式为AuCl.(H2O)3-5和AuS.(H2S)1-2或者是AuHS.(H2S)1-2,其溶解度与气体中H2O、HCl和H2S的逸度成正比。CO2对金的迁移也具有重要作用,能够使金迁移得更远。纳米金的发现,拓宽了找金思路并进一步证明了气体及胶体对金迁移的重要性。金的沉淀与含金介质物理化学条件的改变有关,其主要沉淀机制包括:①温压条件的改变;②流体沸腾及相分离;③流体-围岩反应及流体混合。

Based on previous research work,this paper summarizes the geochemistry of hydrothermal gold mineralization which include the fluids source,forms,transportation and precipitation mechanism of gold.Magmatic hydrothermal,meteoric water and metamorphic fluids are the main source of the gold-bearing hydrothermal fluids.There is a close relationship between the forms of gold and its tansportation.Studies have shown that the dominated fluid of gold transportation is hydrothermal.The main forms of gold in hydrothermal are Au-S complexes and Au-Cl complexes,of which the most important are Au（HS）-2,AuHS,and AuCl-2.Gold can also be transported by vapor,and are likely to form deposits of economic significance through the study of volcanic gases and gold-bearing fluid inclusions.The main forms of gold in vapor is AuCl·（H2O）3-5 and AuS·（H2S）1-2 or AuHS·（H2S）1-2, and gold solubility is directly proportional to the fugacity of H2O,HCl and H2S.CO2 can promote gold to tansport farther through the crust.The discovery of gold nanoparticles not only broaden our idea to prospect gold deposits but also show the importance role of gas and colloidal for gold tansportation.Gold deposition is related to the change of gold-bearing media′s physical-chemical conditions and its main precipitation mechanisms including：（1）the change of temperature and pressure conditions;（2）boiling and phase separation;（3）fluid-wallrock reaction and fluid miscible.