Stratigraphy of the Cretaceous rocks and the Tertiary Ojo Alamo Sandstone, Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah

Abstract

This study of Cretaceous rocks constitutes a part of the ground-water investigation of the Navajo and Hopi Indian Reservations. The Navajo and Hopi Indian Reservations cover about 25,000 square miles, and about one-third of this area is underlain by Cretaceous rocks. The Navajo country-a more general geographic term that encompasses the Navajo and Hopi Indian Reservations-lies principally in northeastern Arizona, but it also includes adjacent parts of northwestern New Mexico, southeastern Utah, and southwestern Colorado.Cretaceous rocks crop out primarily in two large areas-San Juan Basin and Black Mesa-in the eastern and central parts of the Navajo country, respectively. These rocks are as much as 6,500 feet thick in the San Juan Basin and are about 1,500 feet thick on Black Mesa. At several other places in the mapped area are thin isolated 1•emnants of Cretaceous rock.The Lower Cretaceous Burro Canyon Formation, as much as 200 feet thick, is the oldest Cretaceous unit in the Navajo country. It occurs in a very limited area of extrem~ southeastern Utah and adjacent southwestern Colorado. The Burro Canyon consists of conglomerate, sandstone, and green shale and is conformable and intertongues with the underlying Morrison Formation of Late Jurassic age. In northeastern Arizona and northwestern New Mexico, Lower Cretaceous rocks may have been mapped with the Morrison Formation.Above the Burro Canyon Formation, younger Cretaceous strata are much more widespread and record a detailed history of marine transgression (toward the southwest) and regression (toward the northeast). Two major transgressions a1•e recorded in the San Juan Basin, but only the first of these is recorded on Black Mesa.During the first major marine transgression, the Dakota Sandstone and much of the Mancos Shale were laid down. During deposition of the lower part of the Mancos Shale, the shore of the sea lay to the south and west of the Navajo country, but du1•ing the deposition of the upper part of the Mancos, the shoreline migrated back and forth across the Navajo country, as is recorded in the complex assemblage of intertonguing strata. El E2HYDROGEOLOGY, NAVAJO AND HOPI INDIAN RESERVATIONS gression, and its withdrawal was more rapid. As the sea retreated to the northeast, the upper part of the marine Lewis Shale, the marginal marine beds of the Pictured Cliffs Sandstone, and the overlying, dominantly continental beds of the Fruitland Formation and the Kirtland Shale were deposited.A comparison with the standard reference sequence for the Western Interior indicates that the Burro Canyon Formation is of middle Early Cretaceous (Aptian) age. In the northeastern part of the Navajo country, the Dakota Sandstone contains the plant Tempskya and, thus, is partly of Early Cretaceous (Albian) age. Elsewhere,• at least part of the Dakota Sandstone is equivalent in age to the middle of the Greenhorn Limestone. The Mancos Shale includes rocks ranging in age from equivalents of early Greenhorn age to equivalents as young as the Telegraph Creek Formation. I...

Laramide fluvial evolution of the San Juan Basin, New Mexico and Colorado: Paleocurrent and detrital-sanidine age constraints from the Paleocene Nacimiento and Animas formations

“…It is thickest and coarsest in its proximal outcrops in the northwestern part of the basin near Farmington. There, it contains clasts of quartz, chert, silicified igneous rocks, and silicified limestone as much as 15 cm across (O'Sullivan et al, 1972). For details concerning the stratigraphy, depositional environments, and petrology of the Kimbeto Member, see Powell (1972Powell ( , 1973, Lehman (1985), Klute (1986), and Sikkink (1987).…”

Early Paleocene Magnetostratigraphy and Revised Biostratigraphy of the Ojo Alamo Sandstone and Lower Nacimiento Formation, San Juan Basin, New Mexico, USA

“…The SJB preserves two lower Paleocene formations: (1) the Ojo Alamo Sandstone and 2the Nacimiento Formation (Baltz et al, 1966;O'Sullivan et al, 1972). The Ojo Alamo Sandstone unconformably overlies the Maastrichtian Naashoibito Member of the Kirtland Formation (e.g., Baltz et al, 1966;Powell, 1973;Chapin and Cather, 1983;Lehman, 1985;Cather, 2004;Sullivan et al, 2005;Williamson and Weil, 2008a;Williamson et al, 2008; and is composed of gold to yellow colored, cross-bedded, medium to coarsegrained sandstone with interbedded sandstone and siltstone deposits, and localized carbonaceous shale beds and local accumulations of large, nearly complete trees suggesting high depositional energies.…”

“…The Ojo Alamo Sandstone unconformably overlies the Maastrichtian Naashoibito Member of the Kirtland Formation (e.g., Baltz et al, 1966;Powell, 1973;Chapin and Cather, 1983;Lehman, 1985;Cather, 2004;Sullivan et al, 2005;Williamson and Weil, 2008a;Williamson et al, 2008; and is composed of gold to yellow colored, cross-bedded, medium to coarsegrained sandstone with interbedded sandstone and siltstone deposits, and localized carbonaceous shale beds and local accumulations of large, nearly complete trees suggesting high depositional energies. These deposits have been interpreted to represent an alluvial plain in a seasonally dry, sub-tropical climate with one or more sediment sources in the southern Rocky Mountains ( Baltz et al, 1966;O'Sullivan et al, 1972;Powell, 1973;Tidwell et al, 1981;Chapin and Cather, 1983;Sikkink, 1987;Cather, 2004;. Differences in stratigraphic terminology related to the Ojo Alamo Sandstone and underlying Naashoibito Member have created confusion about the relationship between these two units (for example see discussions in Powell, 1973;Williamson andWeil, 2008a, 2008b).…”

“…The Ojo Alamo Sandstone and the Nacimiento Formation from the San Juan Basin (SJB) in northwestern New Mexico and southwestern Colorado (Fig. 1) preserve a nearly continuous succession of lower Paleocene terrestrial deposits (e.g., Baltz et al, 1966;O'Sullivan et al, 1972;Williamson, 1996;Williamson et al, 2008;Cather et al, 2019). The SJB also preserves one of the most complete records of early Paleocene mammalian evolution following the Cretaceous-Paleogene (K-Pg) mass extinction and has been extensively studied for over a century (e.g., Granger, 1917;Matthew, 1937;Simpson, 1959;Williamson and Lucas, 1992;Williamson, 1996;Williamson et al, 2015).…”

Geology of the La Vida Mission Quadrangle, San Juan and McKinley counties, New Mexico

“…Among the many authors who have published on the Late Cretaceous of the San Juan Basin, contributions of the following are of particular relevance to understanding the stratigraphy of the La Vida Mission region: Reeside ( 1924), Sears (1925), Dane (1936), Sears, Hunt, and Hendricks (1941), Pike (1947), Silver (1951), Cobban and Reeside (1952), Beaumont, Dane, and Sears (1956), Weimer (1960), Baltz, Ash, and Anderson (1966), O'Sullivan, Repenning, Beaumont, and Page (1972), Landis, Dane, and Cobban (1973), Molenaar (1977), andFassett (1977).…”