Stratigraphy and Depositional Environments of Middle Proterozoic Rocks, NorthernPart of the Lemhi Range, Lemhi County, Idaho

摘要

Middle Proterozoic rocks in a region of detailed geologic mapping in the northernpart of the Lemhi Range are separated into two packages by the Tertiary Lem Peak normal fault. Strata north of the fault, the main focus of this report, contain thicknesses and lithofacies of the Big Creek and Apple Creek Formations of the Lemhi Group that contrast with those south of the fault. Strata south of the fault, examined mainly in reconnaissance, may have been thrust eastward prior to being downdropped.