Laramide shortening and the influence of Precambrian basement on uplift of the Black Hills, South Dakota and Wyoming, U.S.A.

Evidence for Stress Localization Caused by Lithospheric Heterogeneity From Seismic Attenuation

“…The exception would be if this thickening led to lithospheric delamination and ultimate thinning. In that case, we may expect similar Δt* pattern, but the scenario is less likely considering the small amount of shortening (∼20 km) at the Black Hills during the Laramide Orogeny (Singleton et al, 2019) and the large contrast in lithosphere thickness compared to TBB.…”

Geology of the Mount Taylor area

“…It is interesting to note the remarkable similarity in average shortening azimuths across the entire expanse of the Laramide foreland region as exemplified by an array of researchers, methods, and datasets, although some variability has been mentioned (e.g., ~N-S shortening: Craddock and van der Pluijm, 1999). This is especially true when comparing the results herein with shortening estimates from the most distal Laramide arch, the Black Hills in South Dakota-Wyoming, and its documented mean shortening azimuth of ~068° (Singleton et al, 2019). Similar Late Cretaceous-Paleogene mean shortening directions for numerous Laramide arches suggests (1) a consistent regional shortening direction for the entire Laramide foreland and (2) that Laramide structures, although variably oriented, likely formed from pervasive WSW-ENE-directed shortening.…”

“…Minor thrust faults show overall N-S and WNW-ESE strikes, although it is important to note the shallow dips of these data (~20°). Given the shallow dip, minor thrust data may actually represent Riedel R or P minor faults rather than true thrust faults, although similarly shallow conjugate thrust faults have been documented in other Laramide deformation studies (e.g., Singleton et al, 2019). Kinematic analysis of minor thrust data shows NNW-SSE striking dip slip low-and moderate-angle nodal planes (Fig.…”

“…WSW-ENE shortening has been documented on a variety of Laramide structures throughout the Colorado Plateau and Rocky Mountain regions from Montana-South Dakota to northern Arizona-New Mexico (Bump and Davis, 2003;Bump, 2004;Erslev and Koenig, 2009;Weil and Yonkee, 2012;Singleton et al, 2019). It is interesting to note the remarkable similarity in average shortening azimuths across the entire expanse of the Laramide foreland region as exemplified by an array of researchers, methods, and datasets, although some variability has been mentioned (e.g., ~N-S shortening: Craddock and van der Pluijm, 1999).…”

“…The preliminary dataset presented herein seeks to address some of this complexity by analyzing the geometry and kinematics of a handful of minor faults in post-Pennsylvanian (post-Ancestral Rocky Mountains) rocks across the Zuni Mountains. Many fault kinematic studies have been conducted in both the Colorado Plateau (e.g., Bump and Davis, 2003;Bump, 2004) and the Rocky Mountains (e.g., Erslev and Koenig, 2009;Weil and Yonkee, 2012;Singleton et al, 2019) and provide a base by which to analyze the Zuni arch with similar methods and to compare the results with a regional dataset. Such work has implications for Laramide deformation on the Colorado Plateau, the connection (in space, time, and style) of Colorado Plateau Laramide arches to their larger Rocky Mountain counterparts, and, overall, the tectonic processes responsible for intracontinental strain that formed Laramide arches of the interior western United States.…”