- © The Mineralogical Society Of America
Ore-forming hydrothermal systems often show signs of boiling. In certain classes of deposits—such as low-sulfidation epithermal Au-Ag veins—the chemical consequences of boiling are often considered the cause of ore mineral precipitation, while in others the role of boiling may rather lie in enforcing a favorable pressure-temperature regime. In yet other cases it may, however, be just a passive record of the conditions during ore formation, with little or no direct causal relation to the actual metal enrichment.
A quantitative understanding of the occurrence, the spatial and temporal extent, and the dynamic evolution of boiling zones in hydrothermal systems on a generic level, as well as for specific systems, can help in determining the role of boiling and is thus a potentially valuable tool in economic geology. However, while numerical simulation of the simultaneous flow of coexisting fluid phases (water, oil and gas) is a routinely used key tool in hydrocarbon exploration and reservoir management (Gerritsen and Durlofsky 2005), it has not yet found a similar position in the study and exploration of mineral resources. This is at least partly due to the fact that the geological context of hydrothermal mineral deposits is more difficult to resolve with geophysical methods and, hence, the overall geometry for which simulation of fluid flow should be carried out, is often less clear.
Nevertheless, proper simulation methods have emerged rather recently and have found some application in the hydrothermal regime. Simulations are now a tool to understand and manage individual geothermal fields. O’Sullivan et al. (2001) provide a recent review and Pruess (1990) gives a summary of the basic simulation methods. So-called high-enthalpy geothermal systems often operate under conditions of boiling and are considered to be at least hydrologically equivalent to epithermal hydrothermal systems (Hedenquist et al. 1992). However, studies that have specifically investigated the …