Contributed by Mark Coolbaugh, 4/13/2007

A geothermal area near Tungsten Mountain in Edwards Creek Valley of Churchill County, Nevada was intersected by mineral exploration drilling in 2005 and 2006. The geothermal area lies southeast of Tungsten Mountain along the southeastern margin of the Clan Alpine Mountains and along the northwestern margin of Edwards Creek Valley, mostly in sections 22 and 23, T21N, R38E. Newcrest Resources, Inc. drilled 23 gold exploration holes ranging up to and exceeding 300 m in depth during 2005 and 2006, and all holes hit hot water and/or steam (Tom Kilbey, oral commun., 2006). The northeastern most of these 23 holes (NT-20) is located roughly 60 m N45°W from the corner of sections 23, 24, 13, and 14, and the remaining holes lie southwest of hole NT-20, with the westernmost hole (NT-23) lying approximately 2160 m S67°W of hole NT-20. A 24°C water well was previously known from about 8 km to the southwest (see the description of the Tom Ormechea well), and there were reports of earlier exploration drilling hitting hot water prior to 2003 in this general vicinity.

Because all of the holes hit hot water, the boundaries of the geothermal area, and the location of any deeper geothermal reservoir, remain unclear. However, the currently defined thermal area lies along what appears to be a step over in range front faults along the northwestern margin of Edwards Creek Valley, and it is possible that this step over zone exercises some type of control on subsurface thermal-fluid flow. No hot springs or steam vents are known to occur in the area. Along the range front, a small outcrop of brecciated and argillized volcanic rocks with anomalous gold attracted mineral-exploration interest (John Wood, oral commun., 2006), and small carbonate (tufa) veins and chalcedonic veins are present nearby.

Blowout preventers were installed on the drill rigs used by Newcrest Resources, Inc. and steam was encountered in a number of holes. The hottest measured temperature, obtained with a thermal infrared spectroradiometer on drill pipe, was 96.1°C. Temperature reversals were noted in some holes, but in many cases it appeared that well water (lifted from the holes with air) was a mixture of deeper, higher temperature waters and shallower, cooler waters.

In coordination with the Great Basin Center for Geothermal Energy, hot water from two wells was collected in the field by Derek Amen of Newcrest Resources, Inc. and analyzed at the Desert Research Institute laboratory in 2006. One of those samples produced a significant orange brown precipitate (iron hydroxide) upon cooling and yielded a poor analytical charge balance and consequently the chemistry is not considered accurate. However, the second sample was of clear, 82.2°C water that produced no precipitate and a good charge balance. This second sample was obtained after completing hole NT-23 to a depth of 184.4 m, and after air-lifting water from the bottom of the hole for about 15 minutes at approximately 190 L/min. The Mg-corrected Na-K-Ca geothermometer (Fournier and Truesdell, 1973; Fournier and Potter, 1979) temperature is 174°C and the quartz (no steam loss) geothermometer (Fournier, 1977; Fournier, 1981) temperature is 177°C. The analysis is listed below:

NT-23
TD 184.4 m
Air lifted after completion
Concentrations in mg/L
pH=9.38
HCO3=63.4
CO3=72.1
B=1.09
F=12.2
Cl=38.9
SO4=93.9
Ca=3.48
Fe=1.38
K=10.5
L=2.7
Mg=0.12
Mn=0.010
Na=156
SiO2=190