Fluid Chemistry Studies of Three Low- to Moderate-Temperature Geothermal Resource Areas in Nevada

Abstract

By analyzing thermal and non thermal fluids from three widely separated areas in Nevada useful information on the source and flow paths of the waters was obtained. Major cation and anion compositions show variations which can usually be related to specific locations within the study region. However, this is not always valid, for example, on area studied which is very limited in areal extent shows only minor differences in major ion composition when comparing hot and cold waters. Silica content of fluids was a determined to have no simple relationship to temperature: the highest contents occurring in waters with temperatures significantly below the maximum in each area. Trace element analyses proved to be of limited benefit to our general study but may be helpful in defining recharge or chemical process occurring at a specific site where a known source or sink of the elements can be identified. Stable isotope analysis for oxygen and hydrogen when combined with the constraints imposed by a knowledge of major dissolve constituent composition permit meaningful distinctions to be made between areas and different locations within a single region. These distinctions are readily apparent for the Darrough's Hot Springs area within the Big Smoky Valley which exhibits oxygen isotopic shifts of 7-9 per mil combined with a notably different major ion composition when compared to other thermal fluids in the study area.