Description:
Geological studies of the Early Permian Kaibab Formation in northwestern Arizona have been conducted for over 150 years, but details of its stratigraphy and environmental setting have not been thoroughly evaluated. This paper describes the stratigraphy, elucidates the diagenetic history and provides a revised interpretation of the environments of deposition of the Kaibab Formation throughout the central Grand Canyon. The two members of the Kaibab Formation record significant variations in lithologic and faunal characteristics on a regional scale; therefore, multi-unit subdivisions are proposed for each member based on stratigraphic marker beds. The two subdivisions of the Fossil Mountain Member are characterized by a distinct sequence of chert. A six-unit subdivision of the Harrisburg Member is correlated by distinct outcrop characteristics, lateral changes in lithology, and indigenous fossil assemblages. Within each member, a normal marine fauna found at western locations transitions to an impoverished molluscan fauna toward an eastern shoreline.