| Abstract |
The similarities between active hydrothermal systems and epithermal mineral deposits are well known, and exploration based on applying models of fluid behaviour developed in active hydrothermal systems to exploration for economic precious metal deposits is becoming increasingly commonplace. However, not all hydrothermal systems produce economic deposits. It seems that some "special event" is necessary for an economic concentration of precious metals to be formed. In some cases, these "special events" can be linked to profound hydrological disturbances of the fossil hydrothermal system. There is also evidence for fluctuating hydrological regimes within known active hydrothermal systems. Over the life time of a large hydrothermal system, such disturbances caused by tectonic activity, magmatism, volcanic activity, erosion, climatic changes or other processes may occur at long intervals, but be responsible for producing some of the most significant characteristics of the system, including economic mineral deposits. Such activity may best be regarded as representing a state of punctuated equilibrium, rather than strict uniformitarianism. Recognition of this principle can be of value in exploration for both geothermal energy resources and mineral deposits. |