The Kane Wash Tuff was erupted from a vent area in the southern Delamar Range, Nevada, at lat 37°14′ N., long 114°47′ E. The source location is shown by distribution, thickness, and facies variations of individual cooling units, field evidence for caldera collapse, and petrographic and chemical similarity of pre- and post-collapse rocks.
The Kane Wash Tuff, with a K/Ar age of 14 m.y., is the youngest ash-flow sequence in south-central Lincoln County. It covered an area of 3000 to 4000 sq miles. Original volume was > 200 cu miles. Correlations of tuffs in Nye County, Nevada, Washington County, Utah, and the north Pahranagat Range with the type formation are not considered valid.
Activity of the Kane Springs Wash center began with eruption of lavas. Six or more Kane Wash ash-flow cooling units, at least three of which are multiple-flow, were then emplaced, followed by collapse forming an E.-W. elongated, scalloped caldera 8 by 12 miles in diameter. The depression was filled to overflowing by a complex sequence of welded and nonwelded tuff, lava flows and intrusives, and talus. No resurgence is apparent.
Rocks erupted from the center are mainly comendites, but include trachytic soda rhyolite, trachyte, basalt, and silicic rocks without obvious peralkaline affinities. The peralkaline rocks contain phenocrysts of alkali feldspar, clinopyroxene, fayalite, ± quartz and have the high, B, Be, Ga, Nb, Zr, rare-earth, and halogen contents typical of the comendite-pantellerite-trachyte suit.
Basin-range faulting has only slightly disturbed and tilted the caldera area. Subsequent erosion has magnificently exposed geologic relations.