Grand Canyon Supergroup

Grand Canyon Supergroup
Stratigraphic range: Meso- and Neo-Proterozoic, between 1,250 to
650–700 Ma [1]
TypeSupergroup
Sub-unitsChuar Group
Nankoweap Formation
Unkar Group[1]
UnderliesTonto Group, which is separated from it by the Great Unconformity
OverliesVishnu Basement Rocks
Thickness11,500 ft (3,500 m) to 13,100 ft (4,000 m)
Location
Country United States of America
(Southwestern United States)
Type section
Named forGrand Canyon
Named by(Walcott, 1883, 1894)[2][3]
A view looking north. Unkar Group units lying below the Isis Temple/Cheops Pyramid landforms:
Shinumo Quartzite cliffs (lower part shown on top of photo), above
Hakatai Shale (red-orange-purple slopes), above
Bass Formation(finely-layered, dark slopes), sitting on top of (base units).
Vishnu Basement Rocks (black stratum) within the Granite Gorge and side canyons.

The Grand Canyon Supergroup is a Mesoproterozoic to a Neoproterozoic sequence of sedimentary strata, partially exposed in the eastern Grand Canyon of Arizona. This group comprises the Unkar Group, Nankoweap Formation, Chuar Group and the Sixtymile Formation, which overlie Vishnu Basement Rocks. Several notable landmarks of the Grand Canyon, such as the Isis Temple and Cheops Pyramid, and the Apollo Temple, are surface manifestations of the Grand Canyon Supergroup.

  1. ^ a b Cite error: The named reference ConnorsOthers2020a was invoked but never defined (see the help page).
  2. ^ Walcott, CD (1883) Pre-Carboniferous strata in the Grand Canyon of the Colorado, Arizona. American Journal of Science, 3d ser., vol. 26, pp. 437–42, 484.
  3. ^ Walcott, CD (1894) Precambrian igneous rocks of the Unkar terrane, Grand Canyon of the Colorado. 14th Annual Report for 1892/3, part 2, pp. 492–519, United States Geological Survey, Reston, Virginia.