Abstract: Early Permian Slip and Stratigraphic Consequences of Hurricane and Grand Wash Faults, Northwest Arizona
Walter H. Pierce
Abrupt thickness and facies changes in the Hermit Queantoweap, and Pakoon Formations suggest that the Grand Wash and Hurricane faults were active in Early Permian time. An interpretation of the correlation sections by use of basement-controlled growth faults (syndepositional vertical faults) alleviates problems associated with an interpretation without faults. Two of these problems are: (1) need for a northwestern source for the basal Permian Esplanade Conglomerate of McKee and (2) lack of a deep-water facies in thick stratigraphic sections west of these faults. Thus the "red siltstone marker" of Welsh correlates with the disconformity at the top of the Esplanade Sandstone of the Grand Canyon. This siltstone marks the end of autochthonous sedimentation in the west and rep esents transported soils from the post-Esplanade pre-Hermit disconformity on the east.
The western Queantoweap Formation, though commonly correlated with the Esplanade Sandstone, is younger than the Esplanade. Erosion of the Esplanade provided material for the western Queantoweap Formation. McNair's type section of the Queantoweap Formation is unfortunate, because it includes what previously was informally called "esplanade sandstone" (now formalized by McKee). Sandstones west of the type section differ in age and lithology from the type section. Furthermore, syndepositional slip has limited the sandstones of the Queantoweap Formation to the area west of the Hurricane fault, but the type section lies on the east side of the fault. Hence, retyping and renaming of this sandstone should be considered.
Both the Grand Wash and Hurricane faults were dormant during Pennsylvanian time. Beginning in earliest Permian (Wolfcampian) time, the Grand Wash fault became active. Both the west and east sides moved down in relation to the depositional interface, but the west side moved faster than the east side. Later (probably in early Leonardian time), movement on the Hurricane fault became negative on the west side and positive on the east side relative to deposition. Erosion occurred on the east side and deposition continued on the west side. Substantial displacement on both faults ended in Permian (Leonardian) time prior to deposition of the Coconino Formation.
AAPG Search and Discovery Article #90969©1977 AAPG-SEPM Rocky Mountain Sections Meeting, Denver, Colorado