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Information on the locations and characteristics of faults were collected while conducting fieldwork between 1996 and 2019 in support of geologic mapping in the Buffalo River watershed area of northern Arkansas. A total of 1274 entries on faults were recorded at 452 sites. The observations associated with faults include seven categories of increasing completeness of information.
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Field and microstructural observations from Upheaval Dome, in Canyonlands National Park, Utah, show that inelastic strain of the Wingate Sandstone is localized along compactional deformation bands. These bands are tabular discontinuities (b0.5 cm thick) that accommodate inelastic shear and compaction of inter-granular volume. Measurements of porosity and grain size from nondeformed samples are used to define a set of capped strength envelopes for the Wingate Sandstone. These strength envelopes reveal that compactional deformation bands require at least ca. 0.7 GPa (and potentially more than 2.3 GPa) of effective mean stress in order to nucleate within this sandstone. We find that the most plausible geologic process...
A review of field observations reveals that faults in the upper crust initiate in one of three styles: linkage of pre-existing structures, linkage of precursory structures, or by localization of slip in a precursory shear zone. The first two styles can be characterized by three general stages. During stage 1, faults initiate by shear along pre-existing structures (formed during an earlier event), or by the initiation of precursor structures (formed earlier in the same deformation event). Stage 2 involves the pre-existing or precursor structures becoming linked by differently orientated structures, as stresses are perturbed within the developing fault zone. Linkage allows displacement to increase. A through-going...
    map background search result map search result map Compactional deformation bands in Wingate Sandstone; additional evidence of an impact origin for Upheaval Dome, Utah Fault data collected between 1996 and 2019 from the Buffalo River watershed area, northern Arkansas Compactional deformation bands in Wingate Sandstone; additional evidence of an impact origin for Upheaval Dome, Utah Fault data collected between 1996 and 2019 from the Buffalo River watershed area, northern Arkansas