Mercury Vapor At Salt Wells Area (Henkle, Et Al., 2005)

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Exploration Activity: Mercury Vapor At Salt Wells Area (Henkle, Et Al., 2005)

Exploration Activity Details
Location Salt Wells Area
Exploration Technique Mercury Vapor
Activity Date - 2005

Usefulness useful
DOE-funding Unknown

 
Exploration Basis
Adsorbed mercury soil geochemical surveys and radiometric geophysical surveys were carried out in conjunction with geologic mapping to test the application of these ground-based techniques to geothermal exploration at three prospects in Nevada by Henkle Jr. et al. in 2005. Mercury soil vapor surveys were not widely used in geothermal exploration in the western US at the time, although the association of mercury vapors with geothermal fluids, hot springs, and/or soils has been recognized at the Steamboat Springs, NV,[1] Roosevelt Hot Springs, UT,[2] [3] Dixie Valley, NV,[4] Noya, Japan,[5] and Moana, NV[6] geothermal areas.
 
Notes
Soil sampling and geophysical surveys were conducted at 26 stations along an approximately 1981-m-long line oriented perpendicular to known major structures at Salt Wells. The exact geologic context of the traverse is difficult to discern, as the mapped fault is informally referred to as the “Pony Express Fault” in the text, and no plan map showing the exact location of the sampling line is provided. Sample station spacing along the line was 76.2 m. The same Gas’m technique used to measure desorbed mercury vapors in soils from known fault traces at the Moana Geothermal Area was utilized for the soil geochemical work in this study. The technique measures adsorbed mercury deposited on the silt- and clay-sized fractions of soils as mercury vapors sourced from buried active geothermal systems migrate upward from depth. Approximately 1 kg of soil was sampled from a depth of 30 to 45 cm at each sample station. Mercury analyses of the soil samples were conducted at the Minerals Exploration and Environmental Geochemistry laboratory in Reno, NV. A portion of the minus 325 mesh fraction of each sample was desorbed in a closed container at 50°C for 230 hours and at 100°C for another 70 hours. The desorbed mercury was then measured using a Tekran AFS mercury detector. Both the low- and high-temperature mercury desorb data show elevated values above or near the outcrop of both the mapped and the inferred fault. For the low-temperature data, peaks in the Hg content of the soils occur with a slight offset to the north of the "Pony Express" and the inferred Rock Springs faults, and measured 0.11 and 0.20 ppb, respectively. Peaks in the Hg content of similar magnitude were also encountered at stations 4.5N and 5.0S along the traverse, and may indicate the presence of additional buried faults. The high-temperature desorb data show a broader anomaly in the Hg content of the soils that spans six station above both faults, with a maximum concentration of > 2.0 ppb occurring at the inferred Rock Springs fault. This finding suggests that substantial leakage of mercury vapors occurs along the Rock Springs fault.


Additional References
  1. O.D. Christensen,J.N. Moore,R.M. Capuano. 1980. Trace Element Geochemical Zoning in the Roosevelt Hot Springs Thermal Area, Utah. In: Transactions. GRC Annual Meeting; 09/09/1980; Salt Lake City, UT. Salt Lake City, UT: Geothermal Resources Council; p. 149-152
  2. J.S. Matlick,M. Shiraki. 1981. Evaluation of the Mercury Soil Mapping Geothermal Exploration Techniques. In: Transactions. GRC Annual Meeting; 1981/10/25; Houston, TX. Davis, CA: Geothermal Resources Council; p. 95-98
  3. J.S. Matlick,M. Shiraki. 1981. Evaluation of the Mercury Soil Mapping Geothermal Exploration Techniques. In: Transactions. GRC Annual Meeting; 1981/10/25; Houston, TX. Davis, CA: Geothermal Resources Council; p. 95-98
  4. J.S. Matlick,M. Shiraki. 1981. Evaluation of the Mercury Soil Mapping Geothermal Exploration Techniques. In: Transactions. GRC Annual Meeting; 1981/10/25; Houston, TX. Davis, CA: Geothermal Resources Council; p. 95-98
  5. S.C. Smith. 2003. Thermally Speciated Mercury in Mineral Exploration. In: Programs & Abstracts: Soil and Regolith Geochemistry in the Search for Mineral Deposits. IGES; 2003/09/01; Dublin, CA. Dublin, CA: IGES; p. 78