Date of Award
Master of Science
Geological and Environmental Sciences
Dr. Christopher J. Schmidt
Dr. W. Ulemas Straw
Dr. Ronald B. Chase
Masters Thesis-Open Access
The Snowcrest Range forms the southeastern limb of the Late Cretaceous Blacktail-Snowcrest uplift. The northeast-trending uplift is bounded by the northwest-dipping Snowcrast-Greenhom thrust system which consists of seven thrust zones which merge and flatten at depth along a regional detachment horizon within the Archean basement.
The structures forming the Snowcrest Range are concave westward with trends varying from N 55° E in the southern region to north-south in the northern region. Calcite twin lamellae and fracture orientations indicate that the principal shortening direction was oriented S 85° E during late Cretaceous time. This orientation requires that a significant component of right-lateral strike-slip occurred along the thrusts in the southern Snowcrest Range with an increasing component of dip-slip to the north. Northwest-trending faults acted as tears to accomodate the transfer in displacement along strike.
Basin-range extension collapsed the uplift with normal faults which merge at depth with the Laramide thrusts along the western flank of the range.
McBride, Barry Christopher, "Geometry and Kinematics of the Central Snowcrest Range: A Rocky Mountain Forehand Uplift in Southwestern Montana" (1988). Masters Theses. 1184.