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Publisher Summary This chapter describes the processes and controls on the intertonguing of the Kayenta and Navajo formations in northern Arizona. The Kayenta comprises a heterogeneous assemblage of coarse- to fine-grained clastics that crop out in western Colorado, southwestern Utah, and northern Arizona. The sandy facies is best developed near the type locality at Kayenta, Arizona, where it consists of reddish brown, lenticular, lithic, and feldspathic sandstone interbedded with subordinate amounts of gray to red mudstone. The sandstone units typically have channeled bases and contain small- to medium-scale trough and horizontal stratification. The Navajo is composed largely of fine-grained, well sorted, and subrounded quartz-rich sand. Large-scale features include Nedge–planar and tabular–planar cross-bedding, contorted bedding, horizontally bedded sandstone and siltstone, and cherty limestone. Six facies are recognized within the intertonguing interval of the Navajo and Kayenta formations. Facies were erected based on combinations of lithology, sedimentary structures, and unit geometries. The association with the brecciated zones suggests that deformation occurred at the air-water interface. It is found that moist conditions were relatively common during the early stages of Navajo erg development. |
