1967/01/01 by Richard F. Wilson · 18 citations
Environmental Science · Agricultural and Biological Sciences · #Ecology and Vegetation Dynamics Studies #Rangeland and Wildlife Management #Botany, Ecology, and Taxonomy Studies #Geology #Paleontology #Early Triassic #Permian #Structural basin
paper · pdf · doi:10.3133/b1244d
openalex publication_date 1967/01/01 · openalex created_date 2016/06/24 · openalex updated_date 2025/11/06
Field studies in southwestern Utah and southern Nevada indicate that the Chinle Formation (Upper Triassic) as employed by previous workers in southern Nevada is the probable correlative of the Chinle Formation (Upper Triassic), the Moenave Formation (Triassic?), and the Kayenta Formation (Triassic?) of the Glen Canyon Group in southwestern Utah.Three principal stratigraphie units make up the strata between the Moenkopi Formation (Lower and Middle?Triassic) and the Navajo Sandstone (Triassic?and Jurassic) in southwestern Utah and between the Moenkopi Formation and the equivalent of the Navajo Sandstone, the Aztee Sandstone, in southern Nevada.These units are a basal unit of sandstone and conglomerate; a conformably overlying middle unit of variegated purple, red, and gray sandstone and bentonitic claystone; and an unconformably overlying upper unit of reddish-brown nonbentonitic siltstone and sandstone that grades upward into the overlying Navajo Sandstone or Aztec Sandstone.Prior to recent work, the basal unit in southwestern Utah generally was termed the Shinarump Conglomerate, and the middle and upper units constituted the Chinle Formation.As now recognized in southwestern Utah, the lower and middle members are called, respectively, the Shinarump and Petrified Forest Members of the Chinle Formation.Probable equivalents of these members are recognized in southern Nevada.The upper unit in southwestern Utah comprises the Moenave and the Kayenta Formations of the Glen Canyon Group.Here these two formations are readily distinguished.In southern Nevada, no such division can be made; the strata of the upper unit as a whole are believed to be the probable undifferentiated equivalents of the Moenave and Kayenta Formations.A unit that is lithologically similar to the Chinle Formation is present between the Shinarump(?) Member of the Chinle Formation and the subjacent unquestioned Moenkopi Formation in southern Nevada.This unit was included in the Moenkopi Formation by previous workers in Nevada.Until more is known about this unit, the authors tentatively retain it in the Moenkopi Formation and call it the upper unit of the Moenkopi (?) Formation.