Glen Canyon Group | |
---|---|
Stratigraphic range: | |
Type | Group |
Sub-units | (oldest to youngest) Wingate Sandstone, Moenave Formation, Kayenta Formation, Navajo Sandstone |
Underlies | San Rafael Group |
Overlies | Chinle Formation |
Location | |
Coordinates | 36°56′17″N111°28′59″W / 36.938°N 111.483°W |
Region | Four Corners |
Country | United States |
Type section | |
Named for | Glen Canyon |
Named by | Gregory and Moore |
The Glen Canyon Group is a geologic group of formations that is spread across the U.S. states of Nevada, Utah, northern Arizona, north west New Mexico and western Colorado. It is called the Glen Canyon Sandstone in the Green River Basin of Colorado and Utah. [1]
There are four formations within the group. From oldest to youngest, these are the Wingate Sandstone, Moenave Formation, Kayenta Formation, and Navajo Sandstone. [2] Part of the Colorado Plateau and the Basin and Range, this group of formations was laid down during the Late Triassic and Early Jurassic, with the Triassic-Jurassic boundary within the Wingate Sandstone. [3] [4] The top of the Glen Canyon Group is thought to date to the Toarcian stage of the Early Jurassic. [5]
Asterisks (*) below indicate usage by the U.S. Geological Survey.
The Glen Canyon Group consists of extensive eolian deposits of latest Triassic to Early Jurassic age on the Colorado Plateau. These form the spectacular orange canyon walls of Canyonlands National Park and Paria Canyon as well as the unflooded portions of Glen Canyon. Deposition of the Glen Canyon Group ceased in the Middle Jurassic with the transgression of the Sundance Sea, which separated deposition of the Glen Canyon Group from deposition of the overlying San Rafael Group. [6] The Glen Canyon Group is separated from the underlying Chinle Formation by the regional J-0 unconformity, which represents a time of widespread erosion across western North America. The group is likewise separated from the overlying San Rafael Group by the regional J-2 conformity, representing a renewal of widespread erosion. [7]
The Glen Canyon Group was deposited in a foreland basin created by the uplift of the Sevier Mountains in what is now Nevada and eastern Utah. As a result, the formations of the group thicken to the west. [8]
The Kayenta Formation pinches out and disappears to the north, in the Uintah Basin, and the Wingate Sandstone and Navajo Sandstone become indistinguishable. These remaining eolian beds have sometimes been mapped as simply Glen Canyon Formation, but they correlate with the Nugget Sandstone further north, and it has been recommended that they be assigned to the Nugget Sandstone. [9]
Group rank (stratigraphic order): [2]
There is no designated type locality for this group. It was named by Gregory and Moore prior to 1928 for exposures in walls that form the Glen Canyon of the Colorado River in Coconino County, Arizona and San Juan County, Utah, though their report was not published until 1931. [18] The name had by then been published by Gilluly and Reeside, who gave an overview of the group. [19]
In 1936, A.A. Baker reexamined the group and named the Kayenta Formation. [20] The work was revised again in 1955 by Averitt and others. They assigned the Shurtz Sandstone Tongue (new) and Lamb Point Tongue (new) to the Navajo Sandstone, and Cedar City Tongue (new) and Tenney Canyon Tongue (new) to the Kayenta Formation. [17] In 1957 Harshbarger and others created an overview and revision that assigned the Moenave Formation and divided the Wingate Sandstone into the newly named Rock Point and Lukachukai members. [2] In 1963, the upper contact was revised by Phoenix, who moved the uppermost silstone beds of the Navajo Sandstone into the Judd Hollow Tongue of the Carmel Formation. [21] Poole and Stewart mapped the group into the Green River Basin in 1964, treating it here as a single formation. [22] Areal extent limits were revised by Wilson and Stewart in 1967 [23] and again by Green in 1974, who added the Iyanbito Member. [24] Peterson and Pipiringos revised the upper contact and created an overview in 1979. [13] In 1989 the age of the group was reexamined by Padian [10] and separately by Dubiel (who also revised the lower contact). [25]
Geologic Province:
Prehistoric animals from the various formations of the Glen Canyon Group include several types of dinosaurs, known from both skeletal remains and tracks. Dinosaur finds in the Wingate and Moenave formations are presently almost entirely tracks. The Kayenta Formation has a diverse skeletal fauna including the theropods "Syntarsus" kayentakatae and Dilophosaurus , the prosauropod Sarahsaurus , an unnamed heterodontosaurid, and the armored dinosaurs Scelidosaurus and Scutellosaurus . The Navajo Sandstone has body fossils of the theropod Segisaurus and an Ammosaurus -like prosauropod, and tracks. [5]
The following summarizes vertebrate fossils and tracks reported in the Glen Canyon Group:
Navajo Sandstone:
Kayenta Formation:
Moenave Formation:
Wingate Sandstone:
The geology of the Zion and Kolob canyons area includes nine known exposed formations, all visible in Zion National Park in the U.S. state of Utah. Together, these formations represent about 150 million years of mostly Mesozoic-aged sedimentation in that part of North America. Part of a super-sequence of rock units called the Grand Staircase, the formations exposed in the Zion and Kolob area were deposited in several different environments that range from the warm shallow seas of the Kaibab and Moenkopi formations, streams and lakes of the Chinle, Moenave, and Kayenta formations to the large deserts of the Navajo and Temple Cap formations and dry near shore environments of the Carmel Formation.
The exposed geology of the Capitol Reef area presents a record of mostly Mesozoic-aged sedimentation in an area of North America in and around Capitol Reef National Park, on the Colorado Plateau in southeastern Utah.
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
Oligokyphus is an extinct genus of herbivorous tritylodontid cynodont known from the Late Triassic to Early Jurassic of Europe, Asia and North America.
The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.
The Cutler Formation or Cutler Group is a rock unit that is exposed across the U.S. states of Arizona, northwest New Mexico, southeast Utah and southwest Colorado. It was laid down in the Early Permian during the Wolfcampian epoch.
The Moenkopi Formation is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a group in Arizona. Part of the Colorado Plateau and Basin and Range, this red sandstone was laid down in the Lower Triassic and possibly part of the Middle Triassic, around 240 million years ago.
The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In New Mexico, it is often raised to the status of a geological group, the Chinle Group. Some authors have controversially considered the Chinle to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle Formation is part of the Colorado Plateau, Basin and Range, and the southern section of the Interior Plains. A probable separate depositional basin within the Chinle is found in northwestern Colorado and northeastern Utah. The southern portion of the Chinle reaches a maximum thickness of a little over 520 meters (1,710 ft). Typically, the Chinle rests unconformably on the Moenkopi Formation.
The San Rafael Group is a geologic group or collection of related rock formations that is spread across the U.S. states of New Mexico, Arizona, Utah and Colorado. As part of the Colorado Plateau, this group of formations was laid down in the Middle Jurassic during the Bajocian, Bathonian and Callovian Stages.
The Carmel Formation is a geologic formation in the San Rafael Group that is spread across the U.S. states of Wyoming, Utah, Colorado, north east Arizona and New Mexico. Part of the Colorado Plateau, this formation was laid down in the Middle Jurassic during the late Bajocian, through the Bathonian and into the early Callovian stages.
The Wingate Sandstone is a geologic formation in the Glen Canyon Group of the Colorado Plateau province of the United States which crops out in northern Arizona, northwest Colorado, Nevada, and Utah.
The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested as Sinemurian-Pliensbachian, but more recent dating of detrital zircons has yielded a depositional age of 183.7 ± 2.7 Ma, thus a Pliensbachian-Toarcian age is more likely. A previous depth work recovered a solid "Carixian" age from measurements done in the Tenney Canyon. More recent works have provided varied datations for the layers, with samples from Colorado and Arizona suggesting 197.0±1.5-195.2±5.5 Ma, while the topmost section is likely Toarcian or close in age, maybe even recovering terrestrial deposits coeval with the Toarcian Oceanic Anoxic Event. This last age asignation also correlated the Toarcian Vulcanism on the west Cordilleran Magmatic Arc, as the number of grains from this event correlate with the silt content in the sandstones of the upper layers.
In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into supergroups.
Comb Ridge is a linear north to south-trending monocline nearly 80 miles long in Southeastern Utah and Northeastern Arizona. Its northern end merges with the Abajo Mountains some eleven miles west of Blanding. It extends essentially due south for 45 km (28 mi) to the San Juan River. South of the San Juan the ridge turns to the southwest and is more subdued in expression as it extends for an additional 67 km (42 mi) to Laguna Creek 9 km (5.6 mi) east of Kayenta, Arizona.
The Moenave Formation is a Mesozoic geologic formation, in the Glen Canyon Group. It is found in Utah and Arizona.
Kayentavenator is a genus of small carnivorous tetanuran dinosaur that lived during the Early Jurassic Period; fossils were recovered from the Kayenta Formation of northeastern Arizona and were described in 2010.
Sarahsaurus is a genus of basal sauropodomorph dinosaur which lived during the Early Jurassic period in what is now northeastern Arizona, United States.
Coelophysis? kayentakatae is an extinct species of neotheropod dinosaur that lived approximately 200–196 million years ago during the early part of the Jurassic Period in what is now the southwestern United States. It was originally named Syntarsus kayentakatae, but the genus Syntarus was found to be preoccupied by a Colydiine beetle, so it was moved to the genus Megapnosaurus, and then to Coelophysis. A recent reassessment suggests that this species may require a new genus name.
The Rock Point Formation is a geologic formation in New Mexico, Arizona, and Utah. It preserves fossils dating back to the late Triassic.
The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.
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