Polk Creek Shale

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Polk Creek Shale
Stratigraphic range: Ordovician
Type Formation
Unit ofnone
Sub-unitsnone
Underlies Blaylock Sandstone
Overlies Bigfork Chert
Thickness50 to 225 feet [1]
Lithology
Primary Shale
Location
Region Arkansas, Oklahoma
Country United States
Type section
Named forPolk Creek, Montgomery County, Arkansas
Named byAlbert Homer Purdue [2]

The Polk Creek Shale is a Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, [3] this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. [2] Purdue assigned Polk Creek in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.

Contents

Paleofauna

Graptolites

C. mississippiensis [5] [6]
C. putillus [5] [6]
C. tridentatus var. maximus [6]
C. ulrichi [5] [6]
D. anceps [6]
D. complanatus [4] [5] [6]
D. elegans [4]
D. forehammeri flexuosus [4]
D. calcaratus [5]
D. calcaratus var. trifidus [6]
D. crassitestus [5] [6]
G. quadrimucronatus [5]
G. quadrimucronatus var. paucithecatus [6]
N. velatus [4]
O. quadrimucronatus [4]
O. spinigerus [4]

See also

References

  1. ↑ McFarland, John David (2004) [1998]. "Stratigraphic summary of Arkansas" (PDF). Arkansas Geological Commission Information Circular. 36: 19. Archived from the original (PDF) on 2016-12-21. Retrieved 2018-01-09.
  2. 1 2 Purdue, A.H. (1909). Slates of Arkansas. Geological Survey of Arkansas. pp. 30, 35.
  3. ↑ Griswold, L.S. (1892). "Whetstones and the novaculites". Annual Report of the Geological Survey of Arkansas for 1890. 3.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 Miser, Hugh D.; Purdue, A.H. (1929). "Geology of the De Queen and Caddo Gap quadrangles, Arkansas". U.S. Geological Survey Bulletin. 808: 40–42.
  5. 1 2 3 4 5 6 7 Decker, Charles E. (1935). "Graptolites of the Sylvan Shale of Oklahoma and Polk Creek Shale of Arkansas". Journal of Paleontology. 9 (8).
  6. 1 2 3 4 5 6 7 8 9 Decker, Charles E. (1936). "Some tentative correlations on the basis of graptolites of Oklahoma and Arkansas". Bulletin of the American Association of Petroleum Geologists. 20 (3): 301–311.


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