Date of Award:
Master of Science (MS)
Clyde T. Hardy
A detailed study was made of the James Peak-Sharp Mountain area, in the southern part of the Bear River Range, Utah. The mapped area is located in north-central Utah between lat. 41°22'30" N. and lat. 41°30' N. and long. 111°42'30" W. and long. 111°46' W. It measures about 3.8 miles in the east-west direction and 8.7 miles in the north-south direction. The area is centered about 22 miles south-southeast of Logan, Utah.
Stratigraphic units of late Precambrian to Mississippian age underlie the mapped area. The Precambrian units include the Mutual and Browns Hole Formations. The Brigham, Langston, Ute, Blacksmith, Bloomington, Nounan, and St. Charles Formations make up a complete Cambrian section. The Ordovician Garden City and Swan Peak Formations, the Ordovician-Silurian Laketown Formation, the Devonian Water Canyon and Hyrum Formations, and the Mississippian Lodgepole and Humbug Formations overlie the St. Charles in normal succession.
The oldest unit the Precambrian Mutual Formation, crops out in the southern part of the area on the eastern side of James Peak. The rock units are progressively younger toward the northern part of the area. Mesozoic rocks are not present. The Salt Lake Formation of Tertiary age directly overlies the Paleozoic rocks.
The main structural feature of the area is an asymmetrical north-south-trending anticline. The eastern flank dips more steeply than the western flank. The anticline plunges gently north and dies out southward. This anticline is one of a series of asymmetrical anticlines, all steeper on the east than on the west, that includes the Strawberry Valley anticline to the east and the anticline exposed in upper Wolf Creek Canyon to the west. The late Precambrian and early Paleozoic formations, which dip northeast on the eastern flank of James Peak, make up the northeastern flank of the anticline exposed in upper Wolf Creek Canyon. The early Paleozoic to Devonian formations that form Sharp Mountain and dip gently west make up the western flank of the Strawberry Valley anticline.
Low-angle thrust faults have disrupted the Precambrian and Paleozoic formations on the eastern and southeastern flanks of James Peak. Displacement on the thrust fault north of upper Wellsville Creek is about 2,000 feet. Movement was generally from the west.
Normal faults have disrupted the Paleozoic and Tertiary formations along the eastern margin of Cache Valley and the Paleozoic formations east of McKenzie Mountain. Displacement is indeterminate along the eastern margin of Cache Valley. Maximum displacement, east of McKenzie Mountain, is about 1,750 feet. The normal faults truncate the folds and thrust faults.
The folds and thrust faults were formed during the Laramide orogeny. The normal faults were formed during Basin and Range normal faulting. Basin and Range normal faulting is active at the present time.
Rauzi, Steven L., "Structural Geology of Eastern Part of James Peak Quadrangle and Western Part of Sharp Mountain Quadrangle, Utah" (1979). All Graduate Theses and Dissertations. 3538.
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