Abstract:

Hydrothermal alteration, geochemistry of gold in hydrothermal fluid, concentration form and precipitation mechanism of gold and its forms in sulfide are summarized in this paper. Hydrothermal alteration is the reaction between fluid and host rocks. Mineral assemblages formed during alteration reflect the geochemical feature of oreforming fluids. Gold is always transported as Au-Cl and Au-S complexes in fluids. The change of physicochemical conditions such as temperature, pressure, oxygen fugacity and sulfur fugacity is the effective mechanism for gold precipitation. In fluid with high temperature and pressure, gold tends to concentrate in vapor phase. Au-As and Au-Sb associations are common in gold deposit. In hydrothermal with low sulfur fugacity, native antimony/arsenicnative gold assemblage may precipitate. Gold is probably hosted in sulfide as inclusion or solid solution after precipitated from fluid.

Key words: geochemistry, hydrothermal alteration, behavior of gold in hydrothermal fluid