Geology of the Sheeprock Thrust Sheet, Central Utah - New Insights

Proterozoic sedimentary rocks in the Sheeprock and the adjacent West Tintic Mountains in northcentral Utah were thought to be deformed and transported along the Sheeprock and Pole Canyon thrusts during the Cretaceous to early Tertiary Sevier Orogeny. Evidence from the observed stratigraphy, stratigraphic separation diagrams, downplunge projections of the structure, large-scale relationships between bedding and cleavage orientations, microstructural observations and finite strain data indicate that the Pole Canyon and the Sheeprock thrusts are the same fault, the Sheeprock thrust. The Sheeprock thrust was folded into a gentle synform and subsequently offset by motion along the Indian Springs fault. Based on the offset pattern of the folded Sheeprock thrust along the Indian Springs fault and multiple slickenlines on the Indian Springs fault, two components of motion are recognized; a dextral strike-slip component and a dip-slip component of motion where the southern block is downthrown. The relative age between the two components is not clear.