Stanley Shale

The Stanley Shale, or Stanley Group, is a Mississippian stratigraphic unit in the Ouachita Mountains of Arkansas and Oklahoma. First described in Arkansas in 1892,[4] this unit was not named until 1902 by J.A. Taff in his study of the Ouachita Mountains of Oklahoma.[3] Taff assigned the town of Stanley in Pushmataha County, Oklahoma as the type locality, but did not designate a stratotype. After introduction into Arkansas in 1909 by Albert Homer Purdue,[5] the unit was redefined in 1918, when the formation known as the Fork Mountain Slate was abandoned and partially combined into the Stanley Shale.[6] As of 2017, a reference section for the Stanley Shale has yet to be designated.

Stanley Shale Stratigraphic range: Mississippian
Type	Formation
Unit of	none
Sub-units	Hatton Tuff Lentil (AR/OK), Hot Springs Sandstone (AR) Member,[1] Chickasaw Creek Shale Formation (OK), Moyers Formation (OK), Tenmile Creek Formation(OK)[2]
Underlies	Jackfork Sandstone
Overlies	Arkansas Novaculite
Thickness	3,500 to 10,000+ feet[1]
Lithology
Primary	Shale
Location
Region	Arkansas, Oklahoma
Country	United States
Type section
Named for	Stanley, Pushmataha County, Oklahoma
Named by	Joseph A. Taff[3]

The Stanley Shale is recognized as a geologic formation with two sub-units in Arkansas, the Hatton Tuff Lentil and the Hot Springs Sandstone Member,[1] however, several others have been proposed. These include the Chickasaw Creek Member,[7] Chickasaw Creek Tuff,[8] Gap Ridge Sandstone Member,[9] Moyers Member,[7] Parker Hill Sandstone Member,[9] Polk County Ash Bed,[10] and Tenmile Creek Member.[7] In 1963, it was first proposed to raise the rank of the Stanley Shale Formation to Group status in Arkansas,[11] with proposed sub-units consisting of the Chickasaw Creek Formation, Moyers Formation (with the Gap Ridge Sandstone and Parker Hill Sandstone Members), and Ten Mile Creek Formation.[12] However, the proposal was not accepted and the unit remained as a formation.

In Oklahoma, this unit is recognized as a group called the Stanley Group composed of three formations: the Chickasaw Creek Shale Formation, the Moyers Formation, and the Tenmile Creek Formation. The Hatton Tuff Lentil, recognized in Arkansas, is also in Oklahoma as a unit of the Tenmile Creek Formation. Several informal members have been noted including the Smithville chert lentil, the Faith chert member, and the Chickasaw Creek tuff among others [2]

Mining in the Stanley Shale is limited to cinnabar, barite, and quartz. Cinnabar is primarily used for mercury, however, production in Arkansas essentially ended by the mid-20th century. Barite mining, mostly useful for oil and gas drilling fluid, is ongoing.[13]

Paleoflora

Adiantites A. stanleyanus[14] Alloiopteris A. arkansana[14] Aphlebia[14] Archaeocalamites A. coralloides[14] A. stanleyensis[14] Calymmatotheca[14] Calamites C. menae[14] C. miseri[14]

Lepidodendron L. subclypeatum[14] Lepidostrobus L. peniculus[14] Neuropteris N. elrodi[14] Palmatopteris P. subgeniculata[14] Rhabdocarpos R. secalicus[14] Rhodea R. goepperti[14]

Sphenophyllum S. arkansanum[14] Sphenopteridium S. dawsoni[14] Sphenopteris[14] Stigmaria[14] Trigonocarpum T. gillhami[14] T. vallisjohanni[14] Wardia W. suspecta[14]

See also

• List of fossiliferous stratigraphic units in Arkansas
• Paleontology in Arkansas

References

1. McFarland, John David (2004) [1998]. "Stratigraphic summary of Arkansas" (PDF). Arkansas Geological Commission Information Circular. 36: 22.
2. Suneson, Neil (2016). "Stratigraphic nomenclature of the Ouachita Mountains in Oklahoma: formal, informal, obsolete, and incorrect or the good, the bad, and the ugly" (PDF). Oklahoma Geology Notes. 75: 5–35. Retrieved 6 June 2018.
3. Taff, Joseph A. (1902). "Description of the Atoka Quadrangle" (PDF). Folios of the Geologic Atlas. 79: 4. doi:10.3133/GF79. Wikidata Q63225784.
4. Griswold, L.S. (1892). "Whetstones and the novaculites" (PDF). Annual Report of the Geological Survey of Arkansas for 1890. 3.
5. Purdue, A.H. (1909). Slates of Arkansas (PDF). Geological Survey of Arkansas.
6. Miser, Hugh D. (1918). "Manganese deposits of the Caddo Gap and De Queen quadrangles, Arkansas" (PDF). U.S. Geological Survey Bulletin. 660C: 59–122. doi:10.3133/B660C. ISSN 0083-1093. Wikidata Q61463723.
7. Cohee, G.V.; Wright, W.B. (1976). "Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1975" (PDF). U.S. Geological Survey Bulletin. 1422-A.
8. Mose, Douglas G. (1969). "The age of the Hatton Tuff of the Ouachita Mountains, southeastern Oklahoma". Geological Society of America Bulletin. 80 (11): 2373–2378. Bibcode:1969GSAB...80.2373M. doi:10.1130/0016-7606(1969)80[2373:TAOTHT]2.0.CO;2. ISSN 0016-7606. Wikidata Q66258936.
9. Stearn, N.H. (1935). "Quicksilver deposits near Little Missouri River, discussion". Transactions of the American Institute of Mining and Metallurgical Engineers. 115: 244–246.
10. Williams, J.F. (1891). "The igneous rocks of Arkansas". Annual Report of the Geological Survey of Arkansas for 1890. 2.
11. Seely, D.R. (1963). "Structure and stratigraphy of the Rich Mountain area, Oklahoma and Arkansas" (PDF). Oklahoma Geological Survey Bulletin. 101.
12. Walthall, B.H. (1967). "Stratigraphy and structure, part of Athens Plateau, southern Ouachitas, Arkansas". American Association of Petroleum Geologists Bulletin. 51 (4): 504–528. doi:10.1306/5d25c0a1-16c1-11d7-8645000102c1865d.
13. Rains, Daniel S.; Hanson, William D. (2017). "Geologic report of Pike County" (PDF). Arkansas Geological Survey County Geologic Report. 62: 28. Retrieved 26 May 2018.
14. White, David (1937). "Fossil plants from the Stanley shale and Jackfork sandstone in southeastern Oklahoma and western Arkansas" (PDF). Professional Paper. 186C: 43–67. doi:10.3133/PP186C. ISSN 2330-7102. Wikidata Q61049457.