Structural Geology of a Portion of the Big Bend Draw Quadrangle, Emery County, Utah

Data acquired from mapping a portion of the 7.5\u27 Big Bend Draw quadrangle. Emery County, Utah reveals structures that differ in orientation and character. Descriptive, kinematic, and dynamic analysis of these structures suggests three classes of deformation that developed from successive events after Middle Jurassic time. The earliest class of deformation is attributed to Sevier-type tectonics. This compressional event produced a low-angle thrust and associated bedding-plane slip along an east-west oriented greatest principle stress axis that resulted in a minimum of 20m (65 ft) of separation between the Carmel Formation and Entrada Sandstone. Sense-of-shear indicators suggesting eastward movement of hanging-wall rocks include asymmetrical folds, sigmoidal gypsum fibers, and axial-plane cleavage. Laramide-style tectonics that formed the San Rafael Anticline produced the second class of deformation. Cognate structures include macroscopic folds and normal faults with the principle stress directions responsible for formation oriented northwest-southeast, at right angles to the axis of the San Rafael Anticline. The third class of deformation is attributed to Basin and Range tectonics. Extension from this event resulted in a strike-slip fault that has a northeast-southwest oriented greatest principle stress axis