Correlation of Mississippian and Pennsylvanian Strata in the Southern Beaverhead Mountain Range, Idaho

Billman, Gary S. and William W. Little
Brigham Young University- Idaho, Rexburg, ID

     Reconnaissance mapping in the southern Beaverhead and Lemhi Mountain Ranges of southeastern Idaho has shown inconsistency in the identification of stratigraphic units, particularly for the Upper Mississippian through Lower Pennsylvanian interval. Most workers agree on the presence of the Mississippian Scott Peak and Pennsylvanian Snaky Canyon Formations, but there has been considerable uncertainty regarding the units between them. For example, Skipp et al. (1979) show the Bluebird Mountain and Big Snowy Formations to occupy this interval; whereas, in another report (Skipp et al 1980) they suggest that the Big Snowy Formation is not recognizable in the area, and Huh (1967) places the South Creek and Surrett Canyon Formations in this position. Recent mapping by Brigham Young University-Idaho students on the Scott Butte Quadrangle at the southern end of the Beaverhead Mountain Range indicates that each of these units is present in that area and that problems in identification are due to deformation associated with Sevier orogenic compression and subsequent Basin and Range extension, which have truncated, overturned, and, in some cases, altered the thicknesses of these units.

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah