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{{Short description|Late Cretaceous geologic formation of the Western United States}}
{{Infobox rockunit
{{Infobox rockunit
| name = Mancos Shale
| name = Mancos Shale
Line 4: Line 5:
| caption = Mancos Shale at its type location just north of Mancos, Colorado
| caption = Mancos Shale at its type location just north of Mancos, Colorado
| type = [[Geologic formation]]
| type = [[Geologic formation]]
| age = [[Albian|Mid Albian]]-[[Campanian]]<br>~{{Fossil range|110|80}}
| age = [[Albian|Mid Albian]]-[[Campanian]]<br />~{{Fossil range|110|80}}
| period = Turonian
| period = Turonian
| prilithology = [[Shale]]
| prilithology = [[Shale]]
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| map_caption =
| map_caption =
}}
}}
[[File:Mancos Shale badlands in Capitol Reef NP.jpg|thumb|Mancos Shale badlands in [[Capitol Reef National Park]], southern Utah.]]
[[File:Mancos Mowry shale oil gas fields.png|thumb|Mancos Shale and [[Mowry Shale]] oil and gas fields within the [[Uinta Basin]] and [[Piceance Basin]]]]
[[File:Uinta Piceance Basin stratigraphic column.png|thumb|[[Stratigraphic column]] showing the relationship of the Mancos and Mowry shales]]
[[File:Mancos Shale at Mesa Butte.jpg|thumb|Tununk Member of the Mancos Shale below the capping Ferron Sandstone Member. West side of the San Rafael Swell, Emery County, Utah.]]
The '''Mancos Shale''' or '''Mancos Group''' is a [[Late Cretaceous]] (Upper Cretaceous) [[Formation (stratigraphy)|geologic formation]] of the [[Western United States]].
The '''Mancos Shale''' or '''Mancos Group''' is a [[Late Cretaceous]] (Upper Cretaceous) [[Formation (stratigraphy)|geologic formation]] of the [[Western United States]].


The Mancos Shale was first described by Cross and Purington in 1899<ref>{{cite book |last1=Cross |first1=C.W. |author-link1=Charles Whitman Cross |last2=Purington |first2=C. W. |year=1899 |chapter=Description of the Telluride quadrangle, Colorado |title=United States Geological Survey Atlas |volume=57}}</ref> and was named for exposures near the town of [[Mancos, Colorado]].
The Mancos Shale was first described by Cross and Purington in 1899<ref name=CrossPurington>{{cite book |last1=Cross |first1=C.W. |author-link1=Charles Whitman Cross |last2=Purington |first2=C. W. |year=1899 |chapter=Description of the Telluride quadrangle, Colorado |title=United States Geological Survey Atlas |volume=57}}</ref> and was named for exposures near the town of [[Mancos, Colorado]].


==Geology==
==Geology==
[[File:Uinta Piceance Basin stratigraphic column.gif|thumb|left|upright=1.2|[[Stratigraphic column]] showing the relationship of the Mancos and Mowry shales]]
The unit is dominated by [[mudrock]] that accumulated in offshore and marine environments of the Cretaceous [[Western Interior Seaway|North American Inland Sea]]. The Mancos was deposited during the [[Cenomanian]] (locally [[Albian]]) through [[Campanian]] [[Age (geology)|ages]], approximately from 95 million years ago ([[Ma (unit)|Ma]]) to 80 Ma.
The unit is dominated by [[mudrock]] that accumulated in offshore and marine environments of the Cretaceous [[Western Interior Seaway|North American Inland Sea]]. The Mancos was deposited during the [[Cenomanian]] (locally [[Albian]]) through [[Campanian]] [[Age (geology)|ages]], approximately from 95 million years ago ([[Ma (unit)|Ma]]) to 80 Ma.


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The lower marine Mancos Shale conformably [[intertongues]] with terrestrial [[sandstone]]s and mudstones of the Dakota and in its upper part grades into and intertongues with the Mesaverde Group. The shale tongues typically have sharp basal contacts and gradational upper contacts. Whereas in the plains east of the Rocky Mountains certain mappable marine shales are identified as formations (e.g., [[Skull Creek Shale|Skull Creek]], [[Graneros Shale|Graneros]]), correlated deposits within the distribution of the Mancos are named as tongues of the greater Mancos Formation.
The lower marine Mancos Shale conformably [[intertongues]] with terrestrial [[sandstone]]s and mudstones of the Dakota and in its upper part grades into and intertongues with the Mesaverde Group. The shale tongues typically have sharp basal contacts and gradational upper contacts. Whereas in the plains east of the Rocky Mountains certain mappable marine shales are identified as formations (e.g., [[Skull Creek Shale|Skull Creek]], [[Graneros Shale|Graneros]]), correlated deposits within the distribution of the Mancos are named as tongues of the greater Mancos Formation.


Thus, the classification broadly corresponds with the [[Colorado Group]] classification of the [[Great Plains]] region. As such, various units of the Colorado Group are recognized within the Mancos in those areas where their distinct facies can be recognized.<ref>{{cite journal |author= Charlse H. Rankin |title= Stratigraphy of the Colorado Group, Upper Cretaceous, in Northern New Mexico |journal= New Mexico Bureau of Mines and Mineral Resources Bulletins |issue= 20 |publisher= New Mexico School of Mines |url= https://geoinfo.nmt.edu/publications/monographs/bulletins/downloads/20/Bulletin020.pdf |page= 5 |access-date= 2018-08-13 |quote= ...that all divisions of the Colorado group (Mancos shale) as described in southern Colorado, except the Fort Hays limestone and the Apishapa shale, can be recognized in northern New Mexico. }}</ref>
Thus, the classification broadly corresponds with the [[Colorado Group]] classification of the [[Great Plains]] region. As such, various units of the Colorado Group are recognized within the Mancos in those areas where their distinct facies can be recognized.<ref name=Rankin>{{cite journal |first1= Charles H. |last1=Rankin |year=1944 |title= Stratigraphy of the Colorado Group, Upper Cretaceous, in Northern New Mexico |journal= New Mexico Bureau of Mines and Mineral Resources Bulletins |issue= 20 |publisher= New Mexico School of Mines |url= https://geoinfo.nmt.edu/publications/monographs/bulletins/downloads/20/Bulletin020.pdf |page= 5 |access-date= 2018-08-13 |quote= ...that all divisions of the Colorado group (Mancos shale) as described in southern Colorado, except the Fort Hays limestone and the Apishapa shale, can be recognized in northern New Mexico. }}</ref>
{{clear left}}

==Occurrences==
==Occurrences==
[[File:Mancos Mowry shale oil gas fields.png|thumb|right|Mancos Shale and [[Mowry Shale]] oil and gas fields within the [[Uinta Basin]] and [[Piceance Basin]]]]
[[File:Mancos Shale badlands in Capitol Reef NP.jpg|thumb|Mancos Shale badlands in [[Capitol Reef National Park]], southern Utah.]]
The Mancos occurs in the [[Basin and Range Province]], the [[Colorado Plateau|Colorado Plateau Province]], and the [[San Juan Mountains|San Juan Mountains Province]].
The Mancos occurs in the [[Basin and Range Province]], the [[Colorado Plateau|Colorado Plateau Province]], and the [[San Juan Mountains|San Juan Mountains Province]].


===Structural basins===
===Structural basins===
The unit also occurs in the following [[structural basin]]s:<ref name="USGS-Strat">[http://3dparks.wr.usgs.gov/coloradoplateau/lexicon/mancos.htm "Colorado River Basin Stratigraphy: Mancos Shale"] United States Geological Survey</ref>
The Mancos is a diverse unit, with dozens of named subunits in different [[structural basin]]s that often [[Intertongues|intertongue]] with other formations.<ref name="USGS-Strat">[http://3dparks.wr.usgs.gov/coloradoplateau/lexicon/mancos.htm "Colorado River Basin Stratigraphy: Mancos Shale"] United States Geological Survey</ref> The subunits and intertonguing formations (in italics) in each basin, in stratigraphic order, are:

{|
{|
|- style="vertical-align: top;"
|
* Black Mesa Basin<ref>{{cite journal |last1=Kirkland |first1=J.I. |year=1991 |title=Lithostratigraphic and biostratigraphic framework for the Mancos Shale (Late Cenomanian to Middle Turonian) |journal=Geological Society of America Special Paper |volume=260 |page=88 |isbn=978-0-8137-2260-3 |url=https://books.google.com/books?id=Ymn0oyhfBmwC&q=mancos+%22black+mesa+basin%22&pg=PA88 |access-date=16 September 2021}}</ref>
::Upper shale member
::Hopi Sandy Member
::Middle shale member
::Lower shale member
* [[Chama Basin]]<ref>{{cite journal |last1=Landis |first1=E.R. |last2=Dane |first2=C.H. |year=1967 |title=Geologic map of the Tierra Amarilla quadrangle, Rio Arriba County, New Mexico, with description |journal=New Mexico Bureau of Mines and Mineral Resources Geologic Map |volume=19 |url=https://ngmdb.usgs.gov/Prodesc/proddesc_73099.htm |access-date=17 September 2021}}</ref>
::Upper shale unite
::El Vado Sandstone Member
::Middle shale unit
::Cooper Arroyo Sandstone Member
::[[Juana Lopez Member]]
::Lower shale unit
::[[Greenhorn Limestone]]
::[[Graneros Shale]]
* [[Estancia Basin]] (Mancos Group)<ref>{{cite journal |last1=Lisenbee |first1=Alvis |last2=Maynard |first2=Steve |title=Geologic Map of the Captain Davis Mountain Quadrangle, Santa Fe County, New Mexico |journal=New Mexico Bureau of Geology and Mineral Resources Open-file Digital Geologic Map |date=May 2001 |volume=OF-GM 48 |url=https://geoinfo.nmt.edu/publications/maps/geologic/ofgm/downloads/48/OFGM-48_CaptainDavisMountainReport.pdf |access-date=16 September 2021}}</ref>
::[[Niobrara Formation]]
::[[Carlile Shale]]
::Greenhorn Limestone
|
|
* [[Paradox Basin]]<ref name=NuccioCondon>{{cite journal |last1=Nuccio |first1=Vito F. |last2=Condon |first2=Stephen M. |title=Burial and thermal history of the Paradox Basin, Utah and Colorado, and petroleum potential of the Middle Pennsylvanian Paradox Basin |journal=United States Geological Survey Bulletin |date=1996 |volume=2000-O |doi=10.3133/b00O |page=O6|url=https://digital.library.unt.edu/ark:/67531/metadc304484/ }}</ref>
* Black Mesa Basin
:: West and northwest
* [[Estancia Basin]]
:::[[Masuk Formation|Masuk Member]]
* [[Green River (Colorado River)|Green River Basin]]
:::Emery Sandstone
|
:::Blue Gate Shale
* Orogrande Basin
* [[Paradox Basin]]
:::[[Ferron Sandstone]]
:::Tununk Shale
:: North
:::Buck Tongue
:::''[[Castlegate Sandstone]]''
:::Juana Lopez Member
:: Northeast and east
:::Juana Lopez Member
:::Greenhorn Limestone
* [[Piceance Basin]]
* [[Piceance Basin]]
::Buck Tongue<ref name=FisherEtal>{{cite journal |last1=Fisher |first1=D.J. |last2=Erdmann |first2=C.E. |last3=Reeside |first3=J.B. Jr. |title=Cretaceous and Tertiary formations of the Book Cliffs, Carbon, Emery, and Grand Counties, Utah, and Garfield and Mesa Counties, Colorado |journal=United States Geological Survey Professional Paper |series=Professional Paper |date=1960 |volume=332 |doi=10.3133/pp332|doi-access=free }}</ref><ref>{{cite journal |last1= Johnson |first1=S.Y. |last2=Johnson |first2=R.C. |year=1991 |title=Stratigraphic and time-stratigraphic cross sections of Phanerozoic rocks along line A-A', Uinta and Piceance basin area-Eagle basin, Colorado, to eastern Basin-and-Range area, Utah |journal=U.S. Geological Survey Miscellaneous Investigations Series Map |volume=I-2184-A |url=https://ngmdb.usgs.gov/Prodesc/proddesc_10174.htm |access-date=15 September 2021}}</ref>
|
:: Anchor Mine Tongue<ref name=Franczyk>{{cite journal |last1=Franczyk |first1=Karen J. |title=Depositional controls on the late Campanian Sego Sandstone and implications for associated coal-forming environments in the Uinta and Piceance basins |journal=United States Geological Survey Bulletin |date=1989 |volume=1787-F |doi=10.3133/b1787F|doi-access=free }}</ref>
* [[San Juan Basin]]<ref name=newmex>[https://nmgs.nmt.edu/publications/guidebooks/downloads/56/56_p0218_p0226.pdf New Mexico Geological Association.edu: "SURFACE and SUBSURFACE STRATIGRAPHY of the BURRO CANYON FORMATION, DAKOTA SANDSTONE, and INTERTONGUED MANCOS SHALE of the CHAMA BASIN, NEW MEXICO"]; 2005.</ref>
:: Main body
* [[Uintah Basin]]
|}

===Subunits===
The Mancos occurs with the following subunit names (listed alphabetically):<ref name="USGS-Strat" /> ('''bold''': principle reference section at the [[Mancos, Colorado|type location]])<ref name="RefSect">{{cite journal
|authors= R. Mark Leckie, James I. Kirkland, and William P. Elder
|title= Stratigraphic Framework and Correlation of a Principle Reference Section of the Mancos Shale (Upper Cretaceous), Mesa Verde, Colorado
|journal= 48th Annual NMGS Fall Field Conference Guidebook
|volume = Mesozoic Geology and Paleontology of the Four Corners Area
|url=https://nmgs.nmt.edu/publications/guidebooks/downloads/48/48_p0163_p0216.pdf
|year= 1997
|page= 288
|access-date= 2018-08-04
}}</ref><ref name="LewisR">{{citation
|author= Russell K. Lewis
|title= Stratigraphy and depositional environments of the Late Cretaceous (Late Turonian) Codell sandstone and Juana Lopez members of the Carlile shale, southeast Colorado
|series= 2013 - Mines Theses & Dissertations
|url= https://dspace.library.colostate.edu/bitstream/handle/11124/13/Lewis_mines_0052N_10329.pdf
|access-date= 2018-08-14
}}</ref>

{|
|
|
* [[San Juan Basin]]<ref>{{cite journal |last1=Dane |first1=C.H. |year=1948 |title=Geology and oil possibilites of the eastern side of the San Juan basin, Rio Arriba County, New Mexico |journal=U.S. Geological Survey Oil and Gas Investigations Map |volume=OM-78 |url=https://ngmdb.usgs.gov/Prodesc/proddesc_5439.htm |access-date=16 September 2021}}</ref><ref name=newmex>{{cite journal |last1=Owen |first1=Donald E. |last2=Forgas |first2=Angelique M. |last3=Miller |first3=Shawn A. |last4=Stelly |first4=Ryan J. |last5=Owen |first5=Donald E. Jr. |title=Surface and subsurface stratigraphy of the Burro Canyon Formation, Dakota Sandstone, and intertongued Mancos Shale of the Chama Basin, New Mexico |year=2005 |journal=New Mexico Geological Society Field Conference Series |volume=56 |pages=218–226 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/56/56_p0218_p0226.pdf |access-date=15 September 2021}}</ref>
* Anchor Mine Tongue (CO, UT),
::Mulatto Tongue<ref>{{cite journal |last1=O'Sullivan |first1=R.B. |last2=Repenning |first2=C.A. |last3=Beaumont |first3=E.C. |last4=Page |first4=H.G. |title=Stratigraphy of the Cretaceous rocks and the Tertiary Ojo Alamo Sandstone, Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah |journal=United States Geological Survey Professional Paper |series=Professional Paper |date=1972 |volume=521-E |doi=10.3133/pp521E|doi-access=free }}</ref>
* Aspen Member (UT, WY),
::''Dilco Coal Member of [[Crevasse Canyon Formation]]''
* Black Butte Tongue (WY),
::Niobrara Calcareous Shale
* Blue Gate Member (UT),
* [[Carlile Shale|'''Fairport Member''']] (CO)
::Carlile Shale
* [[Greenhorn Limestone|'''Blue Hill Member''']] (CO, NM),
::Greenhorn Limestone
::[[Graneros Shale]]<ref name=Rankin/>
* Buck Tongue (CO, UT),
:: ''Paguate Tongue of Dakota Formation''
* Bull Point Sandstone Member (UT),
:: Clay Mesa Tongue<ref>{{cite journal |last1=Landis |first1=Edwin R. |last2=Dane |first2=C.H. |last3=Cobban |first3=William Aubrey |title=Stratigraphic terminology of the Dakota Sandstone and Mancos Shale, west-central New Mexico |journal=United States Geological Survey Bulletin |date=1973 |volume=1372-J |doi=10.3133/b1372J|doi-access=free }}</ref>
* [[Carlile Shale|Carlile Member]] (NM),
* Socorro Basin<ref>{{cite journal |last1=Hook |first1=Steven C. |title=Contributions to mid-Cretaceous paleontology and stratigraphy of New Mexico — part II |journal=New Mexico Bureau of Mines & Mineral Resources Circular |date=1983 |volume=185 |pages=15–16 |url=https://geoinfo.nmt.edu/publications/monographs/circulars/downloads/185/Circular-185.pdf |access-date=17 September 2021}}</ref>
* Clay Mesa Tongue (NM),
:: D-Cross Tongue
* '''[[Cortez, Colorado|Cortez]] Member''' (CO)
* Cooper Arroyo Sandstone Member (NM),
:: ''[[Gallup Sandstone]]''
* D-Cross Tongue (NM),
:: Pescado Tongue
:: ''[[Tres Hermanos Formation]]''
* Devils Grave Sandstone [Member] (CO),
:: Rio Salado Tongue
* El Vado Sandstone Member (NM),
:: ''Twowells Tongue of Dakota Formation''
* Emery Sandstone Member (UT),
:: Whitewater Arroyo Tongue
* [[Carlile Shale|'''Fairport Member''']] (CO)
|
* Ferron Sandstone Member (CO, UT),
* [[Fort Hays Limestone Member]] (CO),
* Frontier Formation (CO, UT),
* Garley Canyon Sandstone Member (UT),
* [[Graneros Shale|'''Graneros Member''']] (CO, NM),
* [[Greenhorn Limestone|Greenhorn Member]] (NM),
* [[Greenhorn Limestone|Hartland Shale Beds]] (NM),
* Hopi Sandy Member (AZ),
* Horsehead Tongue (NM),
* Hunt Creek Sandstone [Member] (CO),
* [[Juana Lopez (member)|'''Juana Lopez Member''']] (CO, NM),
* Loyd Sandstone Member (CO),
* Masuk Member (UT) or Masuk Tongue (UT),
* Meeker Sandstone Member (CO),
* '''Montezuma Valley Member''' [Carlile] (CO)
* Morapos Sandstone Member (CO),
|
|
* [[Uintah Basin]]<ref>{{cite journal |last1=Walton |first1=P.T. |year=1944 |title=Geology of the Cretaceous of the Uinta basin, Utah |journal=Bulletin of the Geological Society of America |volume=55 |number=1 |pages=91–130|doi=10.1130/GSAB-55-91 |bibcode=1944GSAB...55...91W }}</ref>
* Mowry Member (UT) or [[Mowry Shale]] (CO, UT),
* Mulatto Tongue (NM),
:: Anchor Mine Tongue<ref name=Franczyk/>
* Muley Canyon Sandstone Member (UT),
:: ''[[Sego Sandstone]]''
:: Upper shale member
* [[Niobrara Formation|Niobrara Member]] (CO, NM),
:: [[Frontier Sandstone]]
* Pescado Tongue (AZ, NM),
:: Middle shale member
* Rangely Tongue (CO, UT),
:: [[Aspen Shale]]
* Rio Salado Tongue (NM),
:: Lower shale member
* Sanastee Sandstone Member (NM),
:: [[Mowry Shale]]<ref>{{cite journal |last1=Molenaar |first1=Cornelius M. |last2=Wilson |first2=B.W. |title=The Frontier Formation and associated rocks of northeastern Utah and northwestern Colorado |journal=United States Geological Survey Bulletin |date=1990 |volume=1787-M |doi=10.3133/b1787M|url=https://digital.library.unt.edu/ark:/67531/metadc304453/ |doi-access=free }}</ref>
* Satan Tongue (NM),
* Semilla Sandstone Member (NM),
* [[Smoky Hill Chalk|'''Smoky Hill Member''']] (CO)
* Tocito Sandstone Lentil (CO, NM),
* Tununk Member (UT),
* Whitewater Arroyo Tongue (NM),
* Wildcat Canyon Sandstone Member (UT),
* Wind Rock Tongue (AZ).
|}
|}

==History of investigation==
{{wide image|Mancos Shale at Mesa Butte.jpg|x160px|Tununk Member of the Mancos Shale below the capping Ferron Sandstone Member. West side of the San Rafael Swell, Emery County, Utah.|33%}}
The Mancos Shale was first named by [[Charles Whitman Cross]] and C.W. Purington in 1899, for outcrops near the town of [[Mancos, Colorado]] and along the [[Mancos River]] nearby. The two geologists also traced the unit into the [[Telluride, Colorado]] area.<ref name=CrossPurington/> W.T. Lee had traced the unit north into the [[Grand Mesa]] area, defining it as all marine shale between the Dakota and the Mesaverde.<ref>{{cite journal |last1=Lee |first1=Willis Thomson |title=Coal fields of Grand Mesa and the West Elk Mountains, Colorado |journal=United States Geological Survey Bulletin |date=1912 |volume=510 |doi=10.3133/b510|hdl=2346/65145 |hdl-access=free }}</ref> It was subsequently traced into Utah<ref>{{cite journal |last1=Lupton |first1=C.T. |title=Oil and gas near Green River, Grand County, Utah |journal=United States Geological Survey Bulletin |date=1914 |volume=541-D |doi=10.3133/b541D|doi-access=free }}</ref> and New Mexico.<ref>{{cite journal |last1=Reeside |first1=John B. Jr. |last2=Knowlton |first2=F.H. |title=Professional Paper |journal=United States Geological Survey Professional Paper |date=1924 |volume=134 |doi=10.3133/pp134|doi-access=free }}</ref>

During their work in New Mexico in 1924, J.B. Reeside, Jr., and F.H. Knowlton found that the Mancos Shale could be divided into [[biostratigraphic]] layers corresponding closely to formations of the [[Colorado Group]] further east. By 1944, Rankin had concluded that most of the formations of the Colorado Group could be identified as [[lithostratigraphic]] members of the Mancos Shale as well.<ref name=Rankin/> The unit was raised to [[Group (stratigraphy)|group rank]] by C.E. Jamison in 1911,<ref>{{cite journal |last1=Jamison |first1=C.E. |year=1911 |title=Geology and Mineral Resources of a Portion of Fremont County, Wyo |journal=Wyoming Geological Survey Bulletin|volume=2B |url=https://books.google.com/books?id=Zz0QAAAAIAAJ&q=%22mancos+group%22&pg=PP7 |access-date=21 September 2021}}</ref> and is sometimes given group rank in New Mexico<ref>{{cite book |last1=Zakis |first1=William |chapter=Table Mesa Oil Field San Juan County, New Mexico |title= Geological Symposium of the Four Corners Region |year=1952 |url=https://archives.datapages.com/data/fcgs/data/001/001001/86_four-corners010086.htm |access-date=21 September 2021}}</ref> and Utah<ref>{{cite journal |last1=Roberto |first1=Sarmiento |title=Microfossil Zonation of Mancos Group |journal=AAPG Bulletin |date=1957 |volume=41 |doi=10.1306/0BDA5927-16BD-11D7-8645000102C1865D}}</ref> as well.


==See also==
==See also==
{{Portal|Cretaceous|Paleontology|Earth sciences}}
{{Portal|Paleontology|Earth sciences}}
* [[List of fossiliferous stratigraphic units in Arizona]]
* [[List of fossiliferous stratigraphic units in Arizona]]
* [[List of fossiliferous stratigraphic units in Colorado]]
* [[List of fossiliferous stratigraphic units in Colorado]]

Latest revision as of 07:55, 13 February 2024

Mancos Shale
Stratigraphic range: Mid Albian-Campanian
~110–80 Ma
Mancos Shale at its type location just north of Mancos, Colorado
TypeGeologic formation
Sub-unitsSee text
UnderliesMesaverde Formation
OverliesDakota Group
Lithology
PrimaryShale
Location
Coordinates37°21′11″N 108°17′49″W / 37.353°N 108.297°W / 37.353; -108.297
RegionArizona, Colorado, New Mexico, Utah, Wyoming
Country United States
ExtentBasin and Range, Colorado Plateau & San Juan Mountains Provinces
Type section
Named forMancos, Colorado
Mancos Shale is located in the United States
Mancos Shale
Mancos Shale (the United States)
Mancos Shale is located in Colorado
Mancos Shale
Mancos Shale (Colorado)

The Mancos Shale or Mancos Group is a Late Cretaceous (Upper Cretaceous) geologic formation of the Western United States.

The Mancos Shale was first described by Cross and Purington in 1899[1] and was named for exposures near the town of Mancos, Colorado.

Geology

[edit]
Stratigraphic column showing the relationship of the Mancos and Mowry shales

The unit is dominated by mudrock that accumulated in offshore and marine environments of the Cretaceous North American Inland Sea. The Mancos was deposited during the Cenomanian (locally Albian) through Campanian ages, approximately from 95 million years ago (Ma) to 80 Ma.

Stratigraphically the Mancos Shale fills the interval between the Dakota and the Mesaverde Group.[2]

The lower marine Mancos Shale conformably intertongues with terrestrial sandstones and mudstones of the Dakota and in its upper part grades into and intertongues with the Mesaverde Group. The shale tongues typically have sharp basal contacts and gradational upper contacts. Whereas in the plains east of the Rocky Mountains certain mappable marine shales are identified as formations (e.g., Skull Creek, Graneros), correlated deposits within the distribution of the Mancos are named as tongues of the greater Mancos Formation.

Thus, the classification broadly corresponds with the Colorado Group classification of the Great Plains region. As such, various units of the Colorado Group are recognized within the Mancos in those areas where their distinct facies can be recognized.[3]

Occurrences

[edit]
Mancos Shale and Mowry Shale oil and gas fields within the Uinta Basin and Piceance Basin
Mancos Shale badlands in Capitol Reef National Park, southern Utah.

The Mancos occurs in the Basin and Range Province, the Colorado Plateau Province, and the San Juan Mountains Province.

Structural basins

[edit]

The Mancos is a diverse unit, with dozens of named subunits in different structural basins that often intertongue with other formations.[4] The subunits and intertonguing formations (in italics) in each basin, in stratigraphic order, are:

  • Black Mesa Basin[5]
Upper shale member
Hopi Sandy Member
Middle shale member
Lower shale member
Upper shale unite
El Vado Sandstone Member
Middle shale unit
Cooper Arroyo Sandstone Member
Juana Lopez Member
Lower shale unit
Greenhorn Limestone
Graneros Shale
Niobrara Formation
Carlile Shale
Greenhorn Limestone
West and northwest
Masuk Member
Emery Sandstone
Blue Gate Shale
Ferron Sandstone
Tununk Shale
North
Buck Tongue
Castlegate Sandstone
Juana Lopez Member
Northeast and east
Juana Lopez Member
Greenhorn Limestone
Buck Tongue[9][10]
Anchor Mine Tongue[11]
Main body
Mulatto Tongue[14]
Dilco Coal Member of Crevasse Canyon Formation
Niobrara Calcareous Shale
Carlile Shale
Greenhorn Limestone
Graneros Shale[3]
Paguate Tongue of Dakota Formation
Clay Mesa Tongue[15]
D-Cross Tongue
Gallup Sandstone
Pescado Tongue
Tres Hermanos Formation
Rio Salado Tongue
Twowells Tongue of Dakota Formation
Whitewater Arroyo Tongue
Anchor Mine Tongue[11]
Sego Sandstone
Upper shale member
Frontier Sandstone
Middle shale member
Aspen Shale
Lower shale member
Mowry Shale[18]

History of investigation

[edit]
Tununk Member of the Mancos Shale below the capping Ferron Sandstone Member. West side of the San Rafael Swell, Emery County, Utah.

The Mancos Shale was first named by Charles Whitman Cross and C.W. Purington in 1899, for outcrops near the town of Mancos, Colorado and along the Mancos River nearby. The two geologists also traced the unit into the Telluride, Colorado area.[1] W.T. Lee had traced the unit north into the Grand Mesa area, defining it as all marine shale between the Dakota and the Mesaverde.[19] It was subsequently traced into Utah[20] and New Mexico.[21]

During their work in New Mexico in 1924, J.B. Reeside, Jr., and F.H. Knowlton found that the Mancos Shale could be divided into biostratigraphic layers corresponding closely to formations of the Colorado Group further east. By 1944, Rankin had concluded that most of the formations of the Colorado Group could be identified as lithostratigraphic members of the Mancos Shale as well.[3] The unit was raised to group rank by C.E. Jamison in 1911,[22] and is sometimes given group rank in New Mexico[23] and Utah[24] as well.

See also

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References

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  1. ^ a b Cross, C.W.; Purington, C. W. (1899). "Description of the Telluride quadrangle, Colorado". United States Geological Survey Atlas. Vol. 57.
  2. ^ Weimar, R.J. (1960). "Upper Cretaceous Stratigraphy, Rocky Mountain Area". AAPG Bulletin. 44: 1–20. doi:10.1306/0BDA5F6F-16BD-11D7-8645000102C1865D.
  3. ^ a b c Rankin, Charles H. (1944). "Stratigraphy of the Colorado Group, Upper Cretaceous, in Northern New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Bulletins (20). New Mexico School of Mines: 5. Retrieved 2018-08-13. ...that all divisions of the Colorado group (Mancos shale) as described in southern Colorado, except the Fort Hays limestone and the Apishapa shale, can be recognized in northern New Mexico.
  4. ^ "Colorado River Basin Stratigraphy: Mancos Shale" United States Geological Survey
  5. ^ Kirkland, J.I. (1991). "Lithostratigraphic and biostratigraphic framework for the Mancos Shale (Late Cenomanian to Middle Turonian)". Geological Society of America Special Paper. 260: 88. ISBN 978-0-8137-2260-3. Retrieved 16 September 2021.
  6. ^ Landis, E.R.; Dane, C.H. (1967). "Geologic map of the Tierra Amarilla quadrangle, Rio Arriba County, New Mexico, with description". New Mexico Bureau of Mines and Mineral Resources Geologic Map. 19. Retrieved 17 September 2021.
  7. ^ Lisenbee, Alvis; Maynard, Steve (May 2001). "Geologic Map of the Captain Davis Mountain Quadrangle, Santa Fe County, New Mexico" (PDF). New Mexico Bureau of Geology and Mineral Resources Open-file Digital Geologic Map. OF-GM 48. Retrieved 16 September 2021.
  8. ^ Nuccio, Vito F.; Condon, Stephen M. (1996). "Burial and thermal history of the Paradox Basin, Utah and Colorado, and petroleum potential of the Middle Pennsylvanian Paradox Basin". United States Geological Survey Bulletin. 2000-O: O6. doi:10.3133/b00O.
  9. ^ Fisher, D.J.; Erdmann, C.E.; Reeside, J.B. Jr. (1960). "Cretaceous and Tertiary formations of the Book Cliffs, Carbon, Emery, and Grand Counties, Utah, and Garfield and Mesa Counties, Colorado". United States Geological Survey Professional Paper. Professional Paper. 332. doi:10.3133/pp332.
  10. ^ Johnson, S.Y.; Johnson, R.C. (1991). "Stratigraphic and time-stratigraphic cross sections of Phanerozoic rocks along line A-A', Uinta and Piceance basin area-Eagle basin, Colorado, to eastern Basin-and-Range area, Utah". U.S. Geological Survey Miscellaneous Investigations Series Map. I-2184-A. Retrieved 15 September 2021.
  11. ^ a b Franczyk, Karen J. (1989). "Depositional controls on the late Campanian Sego Sandstone and implications for associated coal-forming environments in the Uinta and Piceance basins". United States Geological Survey Bulletin. 1787-F. doi:10.3133/b1787F.
  12. ^ Dane, C.H. (1948). "Geology and oil possibilites of the eastern side of the San Juan basin, Rio Arriba County, New Mexico". U.S. Geological Survey Oil and Gas Investigations Map. OM-78. Retrieved 16 September 2021.
  13. ^ Owen, Donald E.; Forgas, Angelique M.; Miller, Shawn A.; Stelly, Ryan J.; Owen, Donald E. Jr. (2005). "Surface and subsurface stratigraphy of the Burro Canyon Formation, Dakota Sandstone, and intertongued Mancos Shale of the Chama Basin, New Mexico" (PDF). New Mexico Geological Society Field Conference Series. 56: 218–226. Retrieved 15 September 2021.
  14. ^ O'Sullivan, R.B.; Repenning, C.A.; Beaumont, E.C.; Page, H.G. (1972). "Stratigraphy of the Cretaceous rocks and the Tertiary Ojo Alamo Sandstone, Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah". United States Geological Survey Professional Paper. Professional Paper. 521-E. doi:10.3133/pp521E.
  15. ^ Landis, Edwin R.; Dane, C.H.; Cobban, William Aubrey (1973). "Stratigraphic terminology of the Dakota Sandstone and Mancos Shale, west-central New Mexico". United States Geological Survey Bulletin. 1372-J. doi:10.3133/b1372J.
  16. ^ Hook, Steven C. (1983). "Contributions to mid-Cretaceous paleontology and stratigraphy of New Mexico — part II" (PDF). New Mexico Bureau of Mines & Mineral Resources Circular. 185: 15–16. Retrieved 17 September 2021.
  17. ^ Walton, P.T. (1944). "Geology of the Cretaceous of the Uinta basin, Utah". Bulletin of the Geological Society of America. 55 (1): 91–130. Bibcode:1944GSAB...55...91W. doi:10.1130/GSAB-55-91.
  18. ^ Molenaar, Cornelius M.; Wilson, B.W. (1990). "The Frontier Formation and associated rocks of northeastern Utah and northwestern Colorado". United States Geological Survey Bulletin. 1787-M. doi:10.3133/b1787M.
  19. ^ Lee, Willis Thomson (1912). "Coal fields of Grand Mesa and the West Elk Mountains, Colorado". United States Geological Survey Bulletin. 510. doi:10.3133/b510. hdl:2346/65145.
  20. ^ Lupton, C.T. (1914). "Oil and gas near Green River, Grand County, Utah". United States Geological Survey Bulletin. 541-D. doi:10.3133/b541D.
  21. ^ Reeside, John B. Jr.; Knowlton, F.H. (1924). "Professional Paper". United States Geological Survey Professional Paper. 134. doi:10.3133/pp134.
  22. ^ Jamison, C.E. (1911). "Geology and Mineral Resources of a Portion of Fremont County, Wyo". Wyoming Geological Survey Bulletin. 2B. Retrieved 21 September 2021.
  23. ^ Zakis, William (1952). "Table Mesa Oil Field San Juan County, New Mexico". Geological Symposium of the Four Corners Region. Retrieved 21 September 2021.
  24. ^ Roberto, Sarmiento (1957). "Microfossil Zonation of Mancos Group". AAPG Bulletin. 41. doi:10.1306/0BDA5927-16BD-11D7-8645000102C1865D.
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