Abstract

The stratigraphy and mapped extent of Cambrian strata in the Stansbury and northern Sheeprock Mountains was established in the late 1950s, and was based largely on units established in the East Tintic mining district. Through review of prior work, in conjunction with new stratigraphic traverses and geologic mapping in parts of these two mountain ranges, we recognize a western Utah-type stratigraphic section (similar to that in the Fish Springs and northern House Ranges) rather than the East Tintic-type section. The Stansbury section is about 9400 feet (2900 m) thick, and divisible into the following formations (ascending): Prospect Mountain Quartzite, Pioche Formation, Howell Limestone, Chisholm Formation, Dome Limestone, Whirlwind Formation, Swasey Limestone, Wheeler Formation, Pierson Cove Formation, Trippe Limestone, Lamb Dolomite, Orr Formation, and Notch Peak Formation. A similar Lower-Middle Cambrian section exists in the northern Sheeprock Mountains, but the section is truncated by a fault in the Trippe Limestone. Recognition of this stratigraphic section has important implications for the regional stratigraphic and structural framework of this part of Utah. The Stansbury and Sheeprock Mountains locally mark the eastern extent of the western Utah-type Cambrian section and of major thrust plates within the Sevier fold-thrust belt.