Carmel Formation

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Carmel Formation exposed at Gunlock Reservoir, southwestern Utah.
Carmel Formation near Gunlock, southwestern Utah. The overlying dark unit is the equivalent of the Cretaceous Dakota Formation.
Ripplemarks in a biosparite/grainstone from the Middle Jurassic Carmel Formation, southwestern Utah.

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.[1]

Subunits

Members (alphabetical):[1]

  • 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][1]
  • Paria River Member (UT*),
  • Wiggler Wash Member (UT*),
  • Winsor Member (UT*).

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

History of investigation

Biosparite/grainstone with crinoid columnals (Isocrinus nicoleti) from the Carmel Formation at Mount Carmel Junction, Utah. Scale in mm.

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 (new) 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 assiged 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.[2]

Paleontological Finds

Cross-section of a carbonate hardground encrusted by oysters and bored by bivalves (Gastrochaenolites); Carmel Formation (Middle Jurassic) of southern Utah.

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

Bryozoans

There have been a number of bryozoans found within the Carmel Formation. These finds include but are not limited to seven species of calcareous cyclostome bryozoans as well as a soft-bodied ctenosome bryozoan.[3]

Places found

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.

Geologic Province:[1]

References

  1. ↑ 1.0 1.1 1.2 1.3 GEOLEX database
  2. ↑ For the whole section, except where noted: GEOLEX database: Summary of Citation
  3. ↑ Taylor, P.D., Wilson, M.A. (1999). "Middle Jurassic Bryozoans from the Carmel Formation of Southwestern Utah". Journal of Paleontology 73: 816-830.

External links

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