Date of Award
Master of Science
Mervin J. Bartholomew
Paleoseismites occur throughout the Campanian package exposed in the Elk Basin anticline. Within marine units convolute-bedding typically involves single sandstone beds with vertical to overturned strata on either side of a near-vertical vent, whereas the non-marine Eagle Formation contains planar clastic dikes derived from liquefied sand-source beds. Liquefied sand was injected upward and laterally across mudstone and/or coal along pre-existing planar, near-vertical, near-surface joints. Orientations of 145 sandstone-dikes were compared with 61 previously reported Laramide joint-orientations. Although dike- and joint-trends are similar, dikes preferentially fill cross-joints whereas strike-joints are the dominant later Laramide joint-set. Dike orientations are consistent with their formation during earliest Laramide deformation in non-lithified sediments, whereas, previously measured joints formed later at greater burial depths in lithified strata. Paleoseismite distribution in the Eagle Formation is consistent with a segment boundary along the major thrust between the northern (N70W-trending) and central (N30W-trending) portions of the anticline.
dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.
Jackson, William Thomas Jr., "The Relationship of Campanian Paleoseismites in the Eagle Formation to Initial Laramide Deformation of the Elk Basin Anticline, Wyoming and Montana" (2012). Electronic Theses and Dissertations. 642.