In the type area of southern Utah, the Carmel Formation is divided into the Judd Hollow Member, a basal limestone member; the Crystal Creek Member, mostly mudstone and siltstone, which grades into the Page Sandstone to the east; the Paria River Member, which is also siltstone and mudstone but is separated from the Crystal Creek Member by gypsum beds; and the Winsor Member, which is mudstone, sandstone, and siltstone separated from the Paria River by a basal limestone. Further east, the limestone marker bed pinches out, and the Winsor Member and Paria River Member become indistinguishable and are informally termed the upper member. The upper member contains volcaniclastic beds of rhyolite originating in a volcanic arc just off the edge of the Colorado Plateau.[4]
The formation preserves a Jurassic hardground, rare for North America.[5]
Subunits
Members (alphabetical):
Co-op Creek Limestone Member (UT) (in place of the preempted name Kolob Limestone Member)[6]
In 1928 Gilluly and Reeside stated an intent to name the formation after the village of Mount Carmel, Utah 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.[10] An overview along with a type locality and source of name was stated by Gregory and Moore in 1931.[11] Mackin revised the formation's description and assigned the Homestake Limestone Member to it in 1954.[12] Harshbarger and others created an overview in 1957.[13] Its eastern areal limits were described by Wright and others in 1962.[14] In 1963, western areal limits along with an overview were completed by Schultz and Wright.[15] Another revision was done by Phoenix in 1963 who also added a Judd Hollow Tongue member.[16] 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[17] and again in 1983 by Blakey and others.[3] An overview was completed by Chapman in 1989.[4] Hintze and others conducted isotopic dating and created an overview in 1994.[18]
Paleontological finds
There have been a number of paleontological finds within the Carmel Formation. Among these have been bryozoans,[19] oysters,[5] and dinosaur footprints.[20]
Hardground mollusc community
The formation preserves a rare Jurassic hardground interpreted as a carbonate lagoon between oolitic shoals and a subtidal zone. The hardground community was dominated by bivalves such as Liostrea, Plicatula, and Modiolus. The ichnofossil Gastro-chaenolites is present, often with fossils of Lithophaga preserved inside. The rare bryozoan Arachnidium is found in attachment scars of Liostrea. Though bivalves were abundant, the community is lacking in the diversity seen in other Jurassic hardgrounds, suggesting a restricted shelf environment.[5]
Bryozoans
Bryozoans found within the Carmel Formation include seven species of calcareous cyclostome bryozoans as well as a soft-bodied ctenostome bryozoan.[19]
^ abChapman, Mary G. (1 March 1989). "Implications of rhyolitic ignimbrite boulders in the Middle Jurassic Carmel Formation of southern Utah". Geology. 17 (3): 281–284. doi:10.1130/0091-7613(1989)017<0281:IORIBI>2.3.CO;2.
^ abcWilson, Mark A.; Palmer, Timothy J. (January 1994). "A carbonate hardground in the Carmel Formation (middle Jurassic, SW Utah, USA) and its associated encrusters, borers and nestlers". Ichnos. 3 (2): 79–87. doi:10.1080/10420949409386375.
^ abDoelling, H.H.; Davis, F.D. (1989). "The geology of Kane County, Utah". Utah Geological and Mineral Survey Bulletin. 124. Retrieved 25 October 2021.
^ abcThompson, A.E.; Stokes, W.L. (1970). "Stratigraphy of the San Rafael Group, southwest and south central Utah". Utah Geological and Mineral Survey Bulletin. 87.
^Mackin, J.H. (1954). "Geology and iron ore deposits of the Granite Mountain area, Iron County, Utah". U.S. Geological Survey Miscellaneous Field Studies Map. MF-I4. doi:10.3133/mf14.
^Wright, J.C.; Shawe, D.R.; Lohman, S.W. (1962). "Definition of Members of Jurassic Entrada Sandstone in East-Central Utah and West-Central Colorado". AAPG Bulletin. 46. doi:10.1306/BC74394B-16BE-11D7-8645000102C1865D.
^ abTaylor, Paul D.; Wilson, Mark A. (September 1999). "Middle Jurassic bryozoans from the Carmel Formation of southwestern Utah". Journal of Paleontology. 73 (5): 816–830. doi:10.1017/S0022336000040671.
^Lockley, Martin; Hunt, Adrian; Paquette, Marc; Bilbey, Sue-Ann; Hamblin, Alden (July 1998). "Dinosaur tracks from the Carmel formation, northeastern Utah: Implications for middle Jurassic paleoecology". Ichnos. 5 (4): 255–267. doi:10.1080/10420949809386424.