I recently present an invited colloquium talk to the faculty and students of the Boone Pickens School of Geology at Oklahoma State University. It is always a pleasure to visit another university and discuss science with colleagues, meet with talented graduate students to hear what they are doing, and tour their facilities. My afternoon talk presented results of research completed with a former Ph.D. student Dr. William Chandonia. It was also a pleasure to have dinner at the home of an old friend Dr. Mohamed Abdelsalam and meet with a former S&T Geology and geophysics graduate Chase Watkins who is finishing his Ph.D at OSU.
“The Kanarra Fold-Thrust Structure: The Leading Edge of the Sevier Fold-and-Thrust Belt in Southwest Utah.”
Abstract
The results of detailed bedrock geologic mapping, and geologic cross sections restored to Late Cretaceous time (prior to Basin and Range extension), demonstrate the Kanarra fold-thrust structure is a compound anticline-syncline pair inextricably linked with concomitant thrust faulting that formed during the Sevier orogeny (Chandonia and Hogan, 2023). A previously unrecognized thrust, the Red Rock Trail thrust, is a forelimb shear thrust that was in a favorable orientation and position to have been soft-linked, and locally hard-linked, with the thrust ramp of the basal detachment to form a break thrust. The east verging Red Rock Trail thrust is recognized by a distinctive cataclasite in the Lower Jurassic Navajo Sandstone. The hanging wall of the Red Rock Trail thrust is displaced eastward over the Middle Jurassic Carmel Formation and Upper Cretaceous formations and can be traced for at least 27 km and possibly farther. Stratigraphic relationships in the southern and northern part of the Kanarra fold-thrust structure constrain its development between the early and late Campanian (about 84 to 71 Ma) but possibly younger. In southwestern Utah, initial movement along the Iron Springs thrust at about 100 Ma (Quick and others, 2020) and subsequent eastward advancement of the Sevier deformation front to the Red Rock Trail thrust at about 84 to 71 Ma coincided with well-documented magmatic flare ups in the Cordilleran arc in the hinterland of the Sevier fold-thrust belt. This temporal relationship between magmatic flare ups and thrusting is consistent with a close correspondence between arc-related processes and episodic foreland deformation.