Magma-Hydrothermal Activity in the Salton Sea Geothermal Field Imperial County, California

Abstract

The nature and intensity of hydrothermal activity in the Salton Sea geothermal field (SSGF) require energy release from a still-cooling igneous intrusion. Newly-integrated analyses of near-surface and wellbore thermal conditions, regional and local seismicity, chemistry of reservoir fluids, hydrothermal alteration of rocks, zoning of secondary minerals, and secondary- mineral zonation in the SSGF indicate that (1) active magma-hydrothermal processes here are dispersing energy from an igneous-intrusive complex, on the order of 20 km2 in areal extent, emplaced to within ~5 km of the modern surface in the last 50,000 years; and (2) that these processes are still prograding, but are approaching a state of maturity. Our conclusions clearly imply that the commercially producible Salton Sea geothermal reservoir could be considerably larger than heretofore envisioned. Even with now-conventional technologies, production of this enormous resource could likely be sustained at 102 MW-year per annum levels for centuries into the future.