Date of Award

12-1988

Degree Name

Master of Science

Department

Geosciences

First Advisor

Dr. Christopher J. Schmidt

Second Advisor

Dr. W. Ulemas Straw

Third Advisor

Dr. Ronald B. Chase

Access Setting

Masters Thesis-Open Access

Abstract

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.

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