295 Geologic Maps and Their Derivatives (Posters)
This poster session will highlight new geologic maps, mapping programs, and innovations in geological mapping, including data management, web accessibility, 3D, and applications in water and land management.
Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1
Preliminary 1:24,000 scale geologic mapping of the Pah Rah Mountain 7.5’ quadrangle, western Nevada, USA: implications for Miocene – recent extension and transtension in the western Basin and Range.
Paper number: 295-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM
Authors
Abstract
Western Nevada exemplifies highly differing magnitudes, styles, and timescales of extensional deformation since the late Oligocene/Miocene, which exerts a strong control on the distribution of mineral resources and fault hazards. Mapping of the Pah Rah Mountain 7.5’ quadrangle, near Pyramid Lake, Nevada, indicates a thick sequence of west-dipping Oligocene (31.47 – 25.06 Ma) ash-flow tuffs, which were erupted in central Nevada and flowed westward, present in paleovalleys. Miocene mafic volcanics overlie the ash-flow tuffs along an angular unconformity and are tilted moderately to the west. Mapping also reveals WNW striking normal faulting, north striking Miocene to recent faulting, and NW striking transtensional faults associated with the northern Walker Lane system. These fault systems exert a control on mineral resources of the area, as well as landslide and earthquake hazards. Ongoing detailed mapping by the Nevada Bureau of Mines and Geology, funded largely by the USGS STATEMAP program, helps to constrain the timing and structural style of these fault systems, and ongoing and pending 40Ar/39Ar sanidine ages of Oligocene ash-flow tuffs and Miocene mafic volcanics, geochemical analyses, and structural measurements aid in understanding the timing of deformation and mineralization in the region, and have implications for the timing of Basin and Range extension on the western edge of the Great Basin.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-414555
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