New Mexico Geological Society Annual Spring Meeting — Abstracts

An integrated investigation of the Las Cruces Geothermal Field is currently in progress. A preliminary flow model based on geological, geophysical, and geochemical data is proposed. Temperature-gradient holes have defined the shape and magnitude of the heat-flow anomaly east of Las Cruces, New Mexico. A positive gravity anomaly is congruent. with the thermal feature, suggesting structural and lithologic controls on revervoir flow. Magnesium-corrected Na-K-Ca and chalalcedony geothermometers indicate a reservoir equilibration temperature of 75°C. Downhole temperatures at the western boundary of the surface thermal anomaly are approximately 60°C. A simple thermodynamic model for the reservoir based on data from 300 to 1,200 meter deep wells,and integrated surface heat-flow data predicts a mass flux through the reservoir of 12 million cubic meters per year. Geochemical and piezometric data indicate that discharge is to the west into the Santa Fe Group aquifers. Further geochemical and isotopic work is underway to better define the recharge area for the reservoir and to constrain physical conditions in the reservoir.