Cross folding in southern Bighorn basin
Analysis of Landsat Thematic Mapper imagery coupled with surface structural investigations of well-exposed folds in the southern Bighorn basin have revealed two northwest-trending folds that have been refolded. The eastern boundary of the Owl Creek Mountains is characterized by a well-defined alignment of folds that extend north-northwest from the Owl Creek thrust front. Bridger monocline, Wildhorse Butte anticline, and Red Hole anticline lie along this trend. Initial Laramide folding, probably during latest Cretaceous time, resulted in a single, continuous, north-northwest-trending anticline with a southwestward vergence. This anticline was progressively unfolded from south to north as the Owl Creek Range was thrust southward over the Wind River basin in earliest Eocene time; scissors-like vertical motion along this flexure rotated the axial surface of the early formed Bridger anticline, resulting in a monocline with a reversed vergence (northeastward). Formation of the Thermopolis/East Warm Springs anticline parallel to the north flank of the range accompanied thrusting and effectively refolded the northern end of the Wildhorse Butte anticline along an east-west axis. Faulting of the oversteepened south limb of the Red Hole cross fold was contemporaneous with folding. Cross-cutting fold axes in this area and the Mud Creek area to the west are best explained by a counterclockwise change in stress direction during the latest phase of the Laramide orogeny. Vertical movement along the eastern side of the Owl Creek Range results from differential motion in the hanging wall of the crystalline thrust sheet.
- Research Organization:
- Univ. of Wyoming, Laramie
- OSTI ID:
- 7230378
- Report Number(s):
- CONF-8609129-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:8; Conference: AAPG Rocky Mountain Section meeting, Casper, WY, USA, 7 Sep 1986
- Country of Publication:
- United States
- Language:
- English
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