Abstract

Thermal maturation of sedimentary organic matter after a geologically-short reaction time is most strongly controlled by peak temperature reached in the sedimentary rocks. Thus, it is a useful tool in showing the peak temperature reached in active sedimentary geothermal systems or ancient hydrothermal deposits. This study uses the Cerro Prieto geothermal system as an example of the application of this method in an active system that is now at peak temperature in its central (hottest) portion. Vitrinite reflectance appears to be useful in exploring for newly-heated portions of the system and showing those portions that have cooled. In ancient systems the information provided by vitrinite reflectance studies could be an important aid to exploration for the core of hydrothermal deposits or possibly detecting them at a distance by locally higher thermal maturation values appearing in regional studies.