Sou Hot Springs is located mainly in the SW¨ù Sec. 29, T26N, R38E about 1.6 km north of the Seven Devils Ranch, which lies at the south end of the Sou Hills in northern Dixie Valley. According to Blackwell et al. (2006),
This group of seven or more hot springs and seeps emerges from the summit and flanks of a north-trending travertine deposit roughly 1 km in length that occurs about 1 to 2 km south of the Sou Hills. The alignment suggests fault control but no structure could be seen at the springs. The hot springs are found in circular vertical tubes or discharge from isolated springs and small ponds, mostly on the south end of the travertine deposit. Water level in one of the tubes is at least 3 m below the crest of the travertine and the water has a surface temperature of 57°C but no obvious discharge. This pool is insidious because it does not appear hot, yet any animal or person that would mistakenly fall into this pool is certain to die. This fact has probably resulted in the alternate name ¡°Seven Devils.¡±Other recent temperature measurements indicate maximum temperatures are about 73°C (Ficklin and others, 1986), although Hague and Emmons (1877, p. 705) reported that the hottest springs and pools are 71-85°C, and there was a great variation of temperatures within a short distance. The area consists of a low mound of travertine covering about 5 hectares which is built up to a height of at least 20 m above the plain. Ten to twelve circular hot-spring pools from 2 to 20 m in diameter are reported; however, Nosker (1981) reported eight springs, with only three active
In November 1997, the source temperature of the largest pool could not be safely measured but the discharge temperature is roughly 45°C. The hottest spring, located about 20 m northwest of the largest pool behind heavy brush, is only 1 m in diameter but has a discharge temperature of 73°C and a flow of 4 l/min. This spring also discharges free gas, whereas none of the others do. Total discharge of the entire group is approximately 200 l/min. The travertine is locally colored bright orange from co-deposited Fe-oxides .
Sou Hot Spring water contains relatively low values of SiO2, As, B, Br, and Li, and Cl content is only 80 ppm. The waters do not resemble Dixie Valley Production Field fluids, but display an oxygen-18 shift of about 0.5¢¶. A water sample from the hottest site is tritium dead suggesting a minimum age ¡Ã110 y (Shevenell and Goff, 1995). The gas contains 52 mol-% CO2, 46 mol-% N2, and 0.8 mol-% CH4; H2S and H2 contents are <0.02 and <0.005 mol-%, respectively. Chemical geothermometers indicate subsurface equilibration temperature are &le85°C (Goff et al., 2002; Tables 8 and 12). Mariner and others (1974) estimate that the minimum thermal-reservoir temperatures may be in the 100-114°C range; Reed and others (1983, p. 107) report the most likely reservoir temperature to be 78¨¬C.
Senterfit and others (1976) have reported audiomagnetotelluric data in the Dixie Valley Known Geothermal Resource Area.
Photos
Sou Hot Springs in Dixie (Osobb) Valley (from lithograph, Hauge and Emmons, 877, plate 20).