Kinetics of ore-forming fluids in epithermal systems

As verified by the data of fluid inclusions in minerals in some paleo-hydrothermal systems, a lowering intemperature of the ore-forming fluids and a decrease in salinity occurred simultaneously from the centralzone (deep part) of the deposit profile to its outer zone (shallow part). The usual situation shown byexperimental data is that solubility rises with an increase in temperature, as shown by quartz and manyore minerals. However, the solubility of some minerals increases as the temperature decreases within acertain temperature range. Therefore, continuous deposition cannot be achieved as the temperature of thesystem decreases, as in the cases of calcite, fluorite, and anhydrite. In water and NaCl-HO systems,the solubility of calcite (or anhydrite) decreases with a rise in temperature at < 300℃ (or < 450℃ for