Geologic map of the Northeast quarter of the Bullfrog 15-minute quadrangle, Nye County, Nevada

This study of the northeast quarter of the Bullfrog 15-minute quadrangle was undertaken to determine the stratigraphy and structural setting as part of a regional study in cooperation with the US Department of Energy. Geology was mapped on aerial photographs at a scale of 1:24,000. Alluvial deposits were mapped on photographs and field checked in some cases. Outcrops of Cambrian and Proterozoic rocks in the southeast corner of the map area were taken from mapping by Monsen (1983). Thickness of units are approximate due to varying degrees of internal deformation. Identification of units is queried on the map where it is uncertain. Field terms guided by some petrographic work are used for lava flows and dikes; therefore, latite-type rocks are termed ''latitic,'' dacite-type rocks are ''dacitic,'' and so forth. Crystal content and amount are approximate for units younger than Tbt6. Age determinations for the rock units have been corrected for new K-Ar constants (Dalrymple, 1979). A detachment fault (Maldonado, 1985, 1988) is defined for this study as ''hor-ellipsis a low-angle normal fault that formed at a low angle, has significant displacement, and is of subregional extent'' (Reynolds and Spencer, 1985). The area was previously mapped by Ransome and others (1910) and by Cornwall and Kleinhampl (1961, 1964). A detailed discussion of the structural setting of the area is presented in a paper by Maldonado. 17 refs