Geothermal Exploration in the Vicinity of Lake Elsinore, Southern California

Abstract

Geothermal exploration in the Lake Elsinore area has primarily focused near a cross fault which acts as a conduit for thermal water Flow testing of an exploratory hole indicates and anisotropic aquifer with a maximum transmissivity axis oriented along the fault striking N 11° E. Thermal water migrates laterally throughout the downtown area along a zone of enhanced transmissivity associated with the fault. Thermal water is lower in total dissolved solids, depleted in Ca and Mg and enriched in SiO2, and F as compared to nonthermal water. The difference in chemistry was used to develop a criterion for selecting future exploration targets based on : flow temperature > 25°C, fluoride >1.2 mg/l and silica geotemperature >90°C. A conceptual model in which deep circulation of local meteoric water is proposed. Water derived from the Santa Ana Mountains descends to a depth of 2-2.5 km along major faults bordering Elsinore Trough. As the water descends, it is heated to a temperature of 90°C and then ascends along a fracture zone near the intersection of the Glen Ivy North and cross faults.