Geothermal prospects in New Mexico

Abstract

Fifty-seven areas in New Mexico discharge ground water at a temperature of 90 °F or higher. The data for 46 areas have been field-checked and show that (1) thermal waters occur in the western half of the state, primarily in the Rio Grande and Gila-San Francisco drainage basins; (2) only 16 areas have been discovered by wells whereas 30 areas are marked by springs; (3) the water issues from rocks ranging from Precambrian to Cenozoic age with the Cenozoic rocks predominating; (4) the waters are associated with igneous and sedimentary rocks in about equal proportions; (5) the water occurs primarily in areas of extensive volcanism and secondarily in fault zones; (6) the water discharges from springs near streams but mostly at points well above the river levels; (7) the discharge may be from fractures directly, from beneath a talus cover, or form alluvium, or form some combinations of these (one spring discharges from a tufa mound); (8) the median pH is 7.7, the median maximum-temperature is about 105 °F, the median discharge of springs is 30.5 gpm, and the median concentration of sodium is 167 ppm, of magnesium 6.9 ppm, of calcium 37.6, of lithium 0.30 ppm, and of potassium 10.0 ppm. The obvious factors to be considered in evaluating a thermal anomaly in New Mexico are: 1. (1) temperature of discharging water, 2. (2) volume of discharging water, 3. (3) surface area of anomaly, 4. (4) dispersion-diffusion effects illustrated by water chemistry, and 5. (5) geologic setting. Based on these criteria, the most promising prospects for natural steam in New Mexico are the Animas valley in Hidalgo County, the Cliff-Gila-Riverside area in Grant County, the southern Rio Grande trough, and the Upper Jemez River basin.