Chemical, physical, and radiological quality of selected public water supplies in Florida : January-May 1979

Verde Valley--an area of complex geology where the crust of the North American plate changes from unstable to stable--is in central Arizona in the transition zone between the Basin and Range and the Colorado Plateaus tectonic provinces. Volcanism and tectonism have been progressing northeastward along the transition zone for about 20 million years. The Verde Hot Springs area is the focal point of the intersection of three major lineaments. More than 100 water samples were collected from wells and springs in the valley, and temperatures of the potential geothermal resources were calculated using two geochemical methods or geothermometers--silica and Na-K-Ca geothermometers. Because of the high concentration of dissolved magnesium in the ground water, the silica geotemperatures are considered to be more reliable than the Na-K-Ca geotemperatures. The Camp Verde and Verde Hot Springs areas contain ground water that has quartz-silica geotemperatures of between 99 and 135C and chalcedony-silica geotemperatures of between 73 and 111C. The geochemical evidence to substantiate a geothermal resource in Verde Valley is not conclusive, and further work including test drilling, should be done to verify the silica geotemperatures given in the map. (Kosco-USGS)