New Mexico Geological Society Annual Spring Meeting — Abstracts

An extensive heat flow data base representing over 140 shallow and intermediate geothermal test wells is presented for the Kilbourne Hole -East Potrillo Mountains area of the southern Mesilla Bolson, New Mexico. The data includes temperature/depth information and laboratory determinations of thermal conductivity for wells typically 300, 500, and 2,000 feet deep. Heat flow has been calculated by standard techniques.

Background heat flow in the bolson is 95 ± 21 mWm^-2, a value consistant with reported Basin and Range and Rio Grande Rift heat flow. A zone of anomalously high heat flow is observed in the limestones of the East potrillo Mountain horst block. This anomaly is observed to continue south beneath the alluvium as far as the Mexican border. The average heat flow within the anomalous zone is 222 ± 125 mWm^-2 with the highest value being 668 mWm^-2. Intermediate depth wells (2,000 feet) located between the East Potrillo Mountains and the Mexican border penetrate limestones of the horst block at 600 to 1,900 feet. where the temperatures are 50 to 60°C and the gradients are isothermal. This suggests a significant convective low temperature geothermal reservoir exists in the limestone, with a subsequent steep geothermal gradient above the aquifer, a phenomenon characteristic of horizontally convective geothermal systems.