Abstract

Sheep Mountain Anticline, located near Greybull along the east flank of the Bighorn Basin is a well known and typical, northwest-southeast trending, Laramide fold. This doubly-plunging asymmetrical anticline is deeply dissected and exposes strata ranging in age from the Mississippian (Madison Formation) to the Paleocene (Ft. Union Formation). A detailed structural portrait of the anticline and its accompanying smaller folds was developed by geologic mapping, the measuring of stratigraphic sections, and constructing 17 structural cross sections. This resulted in a structure contour map of the northern part of Sheep Mountain Anticline.

This NW-SE trending fold and two closely associated, N-S trending anticlines were formed by NE-SW compression during the Laramide orogeny. A two-dimensional model for Sheep Mountain Anticline shows a partly basement-cored and thrust-related structure. The interpretation of the regional structural framework indicates synchronous deformation by left-lateral, strike slip faulting in a unidirectional stress-field.