Date of Award
Master of Science
Mervin J Bartholomew
The Heart Mountain Detachment in northwestern Wyoming is one of the largest terrestrial mega-scale gravity-slides. The emplacement followed the Laramide Orogeny and contemporaneous with widespread Eocene activity in the Absaroka Volcanic Province. Analysis of fracture-sets (joints and faults) from selected outcrops of Cambrian to Eocene strata provide a stratigraphic framework for deciphering the regional sequence of brittle fractures. Seven fracture-sets elucidated from ~1,800 fracture azimuthal measurements, depict a brittle deformational sequence of the Pre-Eocene Laramide Orogeny, Absaroka Volcanism and the Heart Mountain Detachment. Three fracture-sets define a Pre-Eocene 48o clockwise rotation of the stress-field associated with Pre-Laramide and Laramide tectonics. Four fracture-sets defined a 60o counterclockwise rotation of the stress-field in the Eocene associated with Absaroka Volcanism, the Heart Mountain Detachment and the collapse of the volcanic edifice. Angular and abutting relationships of the pre-detachment fracture-sets identify the detachment rotated 30o around a vertical axis as the volcanic system collapsed.
dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.
Ellsworth, G Graham, "The Brittle Deformation Sequence at Dead Indian Hill and the Heart Mountain Detachment, Wyoming, USA" (2017). Electronic Theses and Dissertations. 1681.