| Cardenas Basalt Cardenas Lava(s) | |
|---|---|
| Stratigraphic range: | |
.jpg) black-Cardenas Basalt cliffs on the Colorado River. The squarish cliff is the down-dropped Tanner Graben, of Cardenas Basalt. | |
| Type | Geological formation |
| Unit of | Unkar Group |
| Underlies | Nankoweap Formation |
| Overlies | Dox Formation |
| Thickness | 300 m (980 ft) approximate maximum |
| Lithology | |
| Primary | basalt |
| Other | hyaloclastite, sandstone, and lapillite |
| Location | |
| Region | Arizona-east Grand Canyon Lava Butte region on Colorado River, near Lipan Point |
| Country | United States-(Southwestern United States) |
| Type section | |
| Named for | Cardenas Butte and Cardenas Creek |
| Named by | Keyes (1938)[1] and Ford et al. (1972)[2] |
The Cardenas Basalt, also known as either the Cardenas Lava or Cardenas Lavas, is a rock formation that outcrops over an area of about 310 km2 (120 mi2) in the eastern Grand Canyon, Coconino County, Arizona. The lower part of the Cardenas Basalt forms granular talus slopes. Its upper part forms nearly continuous low cliffs that are parallel to the general course of the Colorado River. The most complete, readily accessible, and easily studied exposure of the Cardenas Basalt lies in Basalt Canyon. This is also its type locality.[3][4]
The Cardenas Basalt is part of the Unkar Group. The Unkar Group is about 1,600 to 2,200 m (5,200 to 7,200 ft) thick and composed, in ascending order, of the Bass Formation, Hakatai Shale, Shinumo Quartzite, Dox Formation, and Cardenas Basalt. In ascending order, the Cardenas Basalt is overlain by the Nankoweap Formation, about 113 to 150 m (371 to 492 ft) thick; the Chuar Group, about 1,900 m (6,200 ft) thick; and the Sixtymile Formation, about 60 m (200 ft) thick. The Grand Canyon Supergroup, of which the Unkar Group is the lowermost part, overlies deeply eroded granites, gneisses, pegmatites, and schists that comprise Vishnu Basement Rocks.[3][5][6]
The Cardenas Basalt has also been called the Rama Formation. However this name, which was originally applied to the dikes and sills intruding strata underlying the Cardenas Basalt has been formally abandoned in the geological literature.[3][4]
Note horizontal bedding (with interbedding) of the Dox Formation; also cliffs of Tapeats Sandstone below greenish slopes of the Bright Angel Shale.
- ^ Keyes, C (1938) Basement complex of the Grand Canyon: Pan American Geologist. 20:91–116.
- ^ Ford, TD, WJ Breed, and JW Mitchell (1972) Name and age of the upper Precambrian basalts in the eastern Grand Canyon. Geological Society of America Bulletin. 83(1):223–226.
- ^ a b c Hendricks, JD, and GM Stevenson (2003) Grand Canyon Supergroup: Unkar Group. In SS Beus and M Morales, eds., pp. 39–52, Grand Canyon Geology, 2nd ed. Oxford University Press, New York.
- ^ a b Lucchitta, I, and JD Hendricks (1983) "Characteristics, depositional environment and tectonic interpretations of the Proterozoic Cardenas Lavas, eastern Grand Canyon, Arizona." Geology. 11(3):177–181.
- ^ Elston, DP, and EH McKee (1982) Age and correlation of the late Proterozoic Grand Canyon disturbance, northern Arizona. Geological Society of America Bulletin. 93(8):681–699.
- ^ Karlstrom, KE, BR Ilg, Bradley, D Hawkins, ML Williams, G Dumond, KK. Mahan, and SA Bowring, Samuel (2012) "Vishnu Basement Rocks of the Upper Granite Gorge: Continent formation 1.84 to 1.66 billion years ago." In JM Timmons and KE Karlstrom, eds., pp. 7–24, Grand Canyon geology: Two billion years of earth's history. Special Paper no 294, Geological Society of America, Boulder, Colorado.