Carmel Formation

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.[2]

Carmel Formation
Stratigraphic range: Middle Jurassic
Carmel Formation exposed at Gunlock Reservoir, southwestern Utah
TypeGeological formation
Unit ofSan Rafael Group
UnderliesEntrada Sandstone
OverliesNugget Sandstone
ThicknessFrom 200 feet (60 m) to 1,000 feet (300 m)[1]
Lithology
PrimaryMudstone
OtherSandstone, siltstone, limestone
Location
RegionWyoming, Utah, Colorado, north east Arizona and New Mexico
CountryUS
Type section
Named forMount Carmel
Named byGilluly and Reeside
Year defined1928
Carmel Formation near Gunlock, Utah. The unconformably overlying dark unit is the Upper Cretaceous Iron Springs Formation.

Subunits

Members (alphabetical):[2]

  • Co-op Creek Limestone Member (UT),
  • Crystal Creek Member (UT),
  • Homestake Limestone Member (UT*),
  • Judd Hollow Member (AZ*, UT*) or Judd Hollow Tongue (AZ*, UT*),
  • Kolob Limestone Member (UT) [name violates the 1983 North American Stratigraphic Code],[2]
  • Paria River Member (UT*),
  • Wiggler Wash Member (UT*),
  • Winsor Member (UT*).

(Asterisks mean the name is used by the US Geological Survey).

History of investigation
The Golden Throne, a rock formation in Capitol Reef National Park. Though the park is famous for white domes of the Navajo Sandstone, this dome's color is a result of a lingering section of yellow Carmel Formation carbonate, which has stained the underlying rock.

In 1928 Gilluly and Reeside stated an intent to name the formation after Mount Carmel but did not give a type locality. They noted it as a basal formation in the San Rafael Group in San Rafael Swell, in Emery County, Utah. An overview along with a type locality and source of name was stated by Gregory and Moore in 1931. Mackin revised the formation's description and assigned the Homestake Limestone Member to it in 1954. Harshbarger and others created an overview in 1957. Its eastern areal limits were described by Wright and others in 1962. In 1963, western areal limits along with an overview were completed by Schultz and Wright. Another revision was done by Phoenix in 1963 who also added a Judd Hollow Tongue member. Isotopic dating was conducted by Marvin and others in 1965. The Kolob, Crystal Creek, Paria River, Winsor, and Wiggler Wash members were assigned by Thompson and Stokes in 1970. Areal limits were adjusted by O'Sullivan and Craig in 1973 and again in 1983 by Blakey and others. An overview was completed by Chapman in 1989. Hintze and others conducted isotopic dating and created an overview in 1994.[3]

Paleontological finds

There have been a number of paleontological finds within the Carmel Formation. Among these have been bryozoans, oysters, as well as dinosaur footprints.

Bryozoans

Bryozoans found within the Carmel Formation include seven species of calcareous cyclostome bryozoans as well as a soft-bodied ctenostome bryozoan.[4]

Pictures


  • Cross-section of a carbonate hardground encrusted by oysters and bored by bivalves (Gastrochaenolites); Carmel Formation (Middle Jurassic) of southern Utah.
  • Biosparite/grainstone with crinoid columnals (Isocrinus nicoleti) from the Carmel Formation at Mount Carmel Junction, Utah.
  • Ripplemarks in a biosparite/grainstone from the Middle Jurassic Carmel Formation, southwestern Utah.

Places found

Geologic Province:[2]

References
  1. "Carmel Formation (in San Rafael Group)". 6 September 2015.
  2. GEOLEX database entry for Carmel, USGS (viewed 20 March 2006)
  3. For the whole section, except where noted: GEOLEX database: Summary of Citations for Carmel, USGS
  4. Taylor, P.D., Wilson, M.A. (1999). "Middle Jurassic Bryozoans from the Carmel Formation of Southwestern Utah". Journal of Paleontology 73: 816-830.
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