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- Title
The groundwater flow patterns associated with the formation of the Truth or Consequences, New Mexico geothermal resource.
- Authors
Pepin, Jeff
- Abstract
We have investigated two of the most plausible regional groundwater circulation scenarios responsible for the formation of the Truth or Consequences, New Mexico hot springs (~41 °C) in the southern Rio Grande rift. The first scenario is that the geothermal anomaly is the result of lateral forced convection associated with a gently-dipping carbonate aquifer. The second scenario is that high permeability of crystalline basement rocks permits circulation of groundwater down to depths of 8 km prior to discharging in Truth or Consequences. We constructed a 2D hydrothermal model of the region using FEMOC to test these hypotheses. Model parameters were constrained by calibrating to measured temperatures, specific discharge rates and groundwater residence times. Hot springs geochemistry is consistent with water/rock interaction in a silicate geothermal reservoir, rather than a carbonate system. Peclet-number analysis of temperature profiles suggests specific discharge rates beneath Truth or Consequences range from 2 to 4 m/year, while geothermometry indicates maximum reservoir temperatures are around 167 °C. We were able to reasonably reproduce observed measurements using the permeable-basement scenario while assigning a uniform effective basement permeability of 10-12 m2. Implementing the exponential decay crustal permeability relationships that are often applied in regional groundwater models was unable to reproduce our field measurements. The carbonate-aquifer scenario failed to match observations. Our findings imply that this geothermal system formed as a result of deep groundwater circulation within permeable crystalline basement rocks. Ongoing work is focused on refining our model using aquifer test results and magnetotellurics.
- Subjects
TRUTH or Consequences (N.M.); NEW Mexico; GROUNDWATER flow; GEOTHERMAL resources; HOT springs; RIO Grande Rift; MAGNETOTELLURICS; AQUIFERS
- Publication
New Mexico Journal of Science, 2015, Vol 49, Issue 1, p13
- ISSN
0270-3017
- Publication type
Article