2-M Probe Survey At Salt Wells Area (Coolbaugh, Et Al., 2006)
Exploration Activity: 2-M Probe Survey At Salt Wells Area (Coolbaugh, Et Al., 2006)
|Exploration Activity Details|
|Location||Salt Wells Geothermal Area|
|Exploration Technique||2-M Probe Survey|
|Activity Date||2005 - 2006|
Geochemical water sampling, mineral distribution mapping, and shallow (30 cm) temperature probe measurements were conducted to expand on a previous field mapping study of surface geothermal features at Salt Wells, in order to evaluate the relationship between these features and structures that control geothermal fluid flow.
This study used a modified version of the 2 m temperature probe survey, adapted for the Salt Wells site (where the water table is at or near the land surface) to measure temperatures at relatively shallow depths of 30 cm. A 1/8 inch diameter, 30-cm-long digital K-type thermocouple and probe was used to collect temperature measurements at each sample point. Temperature measurements were taken by inserting the probe into the ground by hand, and required minimal equilibration times of 1-2 minutes owing to the small thermal mass of the device and the level of water saturation of the measured sediments. Temperature surveys were conducted during the winter in February 2005, when background temperatures at 30 cm depth were near a seasonal minimum of 3 to 10°C. A continuous 24 hour temperature test was also conducted using a 3-wire Platinum Resistance Temperature Device (Pt-RTD) in February 2006, in order to demonstrate the stability of temperatures at 30 cm depth, which only varied by +/- 0.1°C during the day. A temperature threshold of 12°C was used to distinguish thermal anomalies from background temperatures; of the several thousand temperature measures taken for this study, a total of 286 readings were above the 12°C cutoff, with 133 measures of > 20°C, and 32 measures of > 38°C. The maximum temperature encountered was 67.2°C. The measured areas of warm ground showed considerably better correlation with major northwest- and north- to northeast-striking structural controls than the more sporadically distributed springs and seeps, and in some cases were used to locate seasonal springs and seeps for water sampling. The authors concluded that the semi-continuous distribution of silicification and warm ground along the northwestern margin and central portion of the Salt Wells basin define a 6-km-long, thermally active north- to northeast-striking structure that broadly aligns with the thermal anomaly identified by the early Anadarko geothermal gradient drilling. This thermal anomaly is thought to relate either to northward flow of thermal groundwater in the subsurface from the inferred zone of upwelling in the southwest corner of the basin, or to intermittent upflow along the north- to northeast-striking structure on the basin’s western margin.
- Mark F. Coolbaugh, Chris Sladek, Chris Kratt, Lisa Shevenell (2006) Surface Indicators of Geothermal Activity at Salt Wells, Nevada, USA, Including Warm Ground, Borate Deposits, and Siliceous Alteration
- Lisa Shevenell, Mark F. Coolbaugh, Chris Sladek, Rick Zehner, Chris Kratt, James E. Faulds, Robin Penfield (2008) Our Evolving Knowledge Of Nevada's Geothermal Resource Potential