Geology of the Newfoundland Mountains, Box Elder County, Utah

The Newfoundland Mountains consist of a single north-south trending range, located in the midst of the Great Salt Lake Deserts west of Great Salt Lake. A well exposed section of Paleozoic rocks in excess of 15,700 feet thick is present. This includes 2000+ feet of Upper ? Cambrian, 5500+ feet of Ordovician, 1313± feet of Silurian, 4200+ feet of Devonian, and 2900+ feet of Permian. Deposits of Mississippian and Pennsylvanian age are absent, and rocks of Permia age lie on Upper Devonian beds with profound unconformity. Precambrian, Mesozoic and Tertiary rocks are not exposed in the range. A basal conglomerate of Leonardian age is present, and suggests a period of uplift and erosion in the Newfoundland Mountains region. Structurally, the range consists of a westward inclined homoclinal block. High-angle normal faults are the dominant structural features in the area, and two prominent fault systems are recognized: one trends east-west and represents two periods of movement; the other trends north-south, with movement between the two periods of east-west faulting. The northern part of the region was intruded by a quartz monzonite pluton presumably in Late Laramide time, and metamorphism and minera ization of the sediments occurred.