Hydrogen and Oxygen Isotope Geochemistry of Cold and Warm Springs from the Tuscarora, Nevada Thermal Area

摘要

Eighteen cold and warm spring water samples from the Tuscarora, Nevada KGRA have been analyzed for hydrogen and oxygen isotope composition and fluid chemistry. Warm springs have deltaD values (-128 to -137 permil) significantly lower than those of cold springs to the north and east of the area, but similar to the deltaD values of cold springs to the west and south (-131 to -135 permil). The recharge area for the warm springs is unlikely to be to the immediate north, which is the local topographic highland in the area. The hydrogen isotope data would permit recharge from areas to the southwest or from high elevations to the southeast (Independence Mountains), a sector consistent with electrical resistivity evidence of fluid flow. Warm springs are HCO sub 3- -rich waters, enriched by a factor of 3 to 10 in Na, HCO sub 3- and SiO sub 2 relative to local cold springs. Average quartz (no steam loss) and Na/K/Ca geothermometer estimates suggest subsurface temperatures of 145 exp 0 and 196 exp 0 C, respectively. The warm springs exhibit poor correlations between either hydrogen or oxygen isotope composition and water temperature or chemistry. The absence of such correlations suggests that there is no single coherent pattern of cold water mixing or evaporation in the thermal spring system. (ERA citation 07:053519)