Abstract: Steamboat Springs is a presently active equivalent of epithermal gold-silver ore-forming systems. Hot-spring sinter deposits contain small amounts of gold, silver, mercury, antimony, and arsenic. Hot-spring activity probably started before extrusion of the basaltic andesite of Steamboat Springs. Old sinter from the Steamboat Springs system occurs in gravels above and below the basaltic andesite. Intense hydrothermal alteration, including almost complete replacement by hydrothermal potassium-feldspar, has affected the basaltic andesite. Three plagioclase separates of differing potassium content from fresh basaltic andesite yielded potassium-argon ages of 2.52 to 2.55 m.y. Basaltic andesite almost completely replaced by potassium-feldspar yielded an age of 1.1 m.y. The source of energy for the thermal convection system is probably a large rhyolitic magma chamber that supplied the pumice and from which the rhyolite domes were emplaced. Sanidine and obsidian from four of the rhyolite domes yielded potassium-argon ages of 1.15 to 1.52 m.y. and obsidian from one of the northeastern domes yielded apparent ages of 2.97 and 3.03 m.y. The data indicate that hydrothermal activity has occurred at Steamboat Springs, possibly intermittently, for more than 2-1/2 m.y. These data agree with other radiogenic age studies indicating 1- and 2-m.y. lifetimes for the hydrothermal systems that generate …

This is a report on the geology and ore deposits of the Goodsprings Quadrangle, Nevada.

From introduction: The present study was undertaken to extend and supplement a mapping program covering several ranges north and northwest of Lake Mead.

From contributions of astrogeology: The principal goal of research in astrogeology is the solution of several cardinal problems of geology...The present volume is the first of a series of professional papers that will describe major results of research in astrogeology.

From introduction: The object of this paper is to describe the salient features of Jurassic diastrophism in parts of the Tonopah and Hawthorne quadrangles in west-central Nevada. The problem is complicated by the lack of continuity of exposures, earlier folding of the older rocks, metamorphism caused by the later granitic in-trusions, and by superposed Tertiary and later normal faults.