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National Geologic Map Database
Geologic Unit: Karnak
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  • Usage in publication:
    • Karnak Member
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
    • Oolite
  • AAPG geologic province:
    • Illinois basin
Publication:

Swann, D.H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks in Illinois: Illinois Geological Survey Report of Investigations, no. 216, 91 p.


Summary:

Karnak Member formally proposed in this report for relatively pure persistent limestone unit in Ste. Genevieve Limestone of Genevievian age. Commonly 10 to 35 ft thick. It overlies sandstone, siltstone, shale, or impure limestone assigned to Spar Mountain Member. At type section, the top 16 ft of an estimated 20 to 25 ft of cross-bedded oolitic limestone is exposed in cuts on IL Hwy 37. Lower beds inadequately exposed in hill slope southeast of junction of highway with gravel road to Belknap. About 300 ft east of junction, top of Karnak lies 51 ft beneath base of Levias Limestone Member of Renault and directly beneath type section of Joppa Member.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Karnak Member
  • Modifications:
    • Areal extent
    • Overview
  • AAPG geologic province:
    • Illinois basin
Publication:

Droste, J.B., and Carpenter, G.L., 1990, Subsurface stratigraphy of the Blue River Group (Mississippian) in Indiana: Indiana Geological Survey Bulletin, no. 62, 45 p.


Summary:

Usage of the Ste. Genevieve Limestone of the Blue River Group in Indiana is here revised. In the subsurface, unit is divided into (ascending) Fredonia, Karnak, and Joppa Members, which are basically equivalent to members of the same name in IL. Levias and Spar Mountain Members of Ste. Genevieve are no longer used in Indiana. This nomenclature replaces that of Shaver and others (1986) as the IN State usage. In outcrop, Joppa is replaced by rocks typical of upper Karnak. Uppermost rocks of the Ste. Genevieve on the surface and in the very shallow subsurface are assigned to the Bryantsville Breccia Bed of the Karnak Member. Bryantsville of previous usage marked the top of the Levias Member. Lost River Chert Bed marks the base of the Fredonia Member and therefore the base of the Ste. Genevieve. Fredonia is stratigraphically extended in this study to include the equivalent to both the Fredonia and Spar Mountain Members as previously used on the outcrop in Indiana.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Karnak Member*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Illinois basin
Publication:

Ridgley, J.L., and Nuccio, V.F., 1995, Source rock potential of the Mississippian St. Louis Limestone in south-central Indiana, IN Evolution of sedimentary basins; Illinois basin: U.S. Geological Survey Bulletin, 2094-D, p. D1-D12.


Summary:

Used as Mississippian (Valmeyeran) Karnak Member of Ste. Genevieve Limestone in IN. Usage follows Droste and Carpenter (1990).

Source: GNU records (USGS DDS-6; Reston GNULEX).


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For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).