New Mexico Geological Society Annual Spring Meeting — Abstracts

Heat flow data derived from subsurface temperatures and rock thermal conductivity can often provide valuable infonnation about the groundwater flow within a region. In the present study bottom-hole temperature data (BHT data) are generally used to make a preliminary study of the subsurface thennal regime along an east-west profile in southeastern New Mexico. Although BHT data are notoriously suspect, these data may be used to detect hydrologically induced anomalies if sufficient data are available over the entire sediment depth of a groundwater basin. Because deep BHT data are typically a good deal less perturbed than are shallow BHT data, the deep BHT values can often provide a heat flow datum for the region which allows shallower, hydrologically induced heat flow anomalies to be recognized. Vertical temperature gradients in the earth are typically several orders of magnitude greater than are horizontal temperature gradients and therefore vertical groundwater advection is generally responsible for anomalous heat flows. If anomaly dependence on depth is recognized an estimate of the depth of vertical groundwater flow can be made.

These concepts are applied to the southern Roswell artesian basin in southeastern New Mexico. A number of interpretations from the heat flow data are consistent with suggestions made in previous studies; e.g. a broad upward cross-fonnational flow discharging to the Pecos River, downward groundwater flow in areas of the High Plains, and a region near the Mescalero Ridge where no observable vertical groundwater flow appears. A very local anomaly in the western part of the study area seems to result from upward groundwater flow along the front of a buried Precambrian horst recently discovered by explorative drilling. The depth of flow in these cases is thought to be from 3000 ft and perhaps as deep as 5000 ft.