Geolex — Ion publications

National Geologic Map Database
Geolex — Significant Publications

Geologic Unit: Ion

Usage in publication:
- Ion member
Modifications:
- Original reference
Dominant lithology:
- Shale
- Limestone
AAPG geologic province:
- Iowa shelf

Publication:

Kay, G.M., 1928, Divisions of the Decorah formation [in northeastern Iowa]: Fort Hays Kansas State College, Science Series, new series, v. 67, p. 16.

Summary:

Pg. 16. Ion member of Decorah formation. Calcareous shale and argillaceous limestones, the limestones irregularly dolomitized in southeastern part of their outcrop in Iowa. The beds become more argillaceous to north and more calcareous to southeast. Thickness 16 feet. Top member of Decorah formation. Rests on Guttenberg limestone member. Fossils are of basal Trenton (Rockland) age [Middle Ordovician]. [See also Kay, 1929 (Jour. Geol., v. 37, no. 7, Oct.-Nov., p. 639-671), who stated this member corresponds fo Fucoid bed and CHASMATOPORA bed of Minnesota.]
Type locality: in ravine along road, in NW/4 sec. 35, T. 96 N., R. 4 W., about 1 mi southwest of hamlet of Ion, [Giard 7.5-min quadrangle], Allamakee Co., northeastern IA.

Source: US geologic names lexicons (USGS Bull. 896, p. 1018; USGS Bull. 1200, p. 1875).

Usage in publication:
- Ion member
Modifications:
- Areal extent
AAPG geologic province:
- Iowa shelf

Publication:

Kay, G.M., 1935, Ordovician System in the Upper Mississippi Valley, IN Kay, G.F., and Trowbridge, A.C., Conference leaders, Upper Mississippi Valley, Iowa City, Iowa, to Duluth, Minnesota: Kansas Geological Society Guidebook for the Annual Field Conference, August 25-September 1, 1935, no. 9, p. 281-295., Prepared in cooperation with Iowa, Illinois, Wisconsin, and Minnesota geol. surveys

Summary:

Pg. 295. Showed his Ion, Guttenberg, and Spechts Ferry members as present in Minnesota and northwestern Illinois. [Age is Middle Ordovician (Trenton).]
[Recognized in northeastern IA, northwestern IL, southeastern MN, and southwestern WI.]

Source: US geologic names lexicons (USGS Bull. 896, p. 1018).

Usage in publication:
- Ion submember
Modifications:
- Revised
AAPG geologic province:
- Sioux uplift

Publication:

Stauffer, C.R., and Thiel, G.A., 1941, The Paleozoic and related rocks of southeastern Minnesota: Minnesota Geological Survey Bulletin, no. 29, 261 p., (incl. geologic map)

Summary:

p. 9 (geol. column), 81, 83-85. Ion considered submember of Decorah shale member of Galena formation in Minnesota. Occurs at top of Decorah; overlies Guttenberg submember. Consists of calcareous shale with layers or lenses of argillaceous limestone. Thickness 15 to 20 feet in St. Paul area, southeastern Minnesota. [Age is Middle Ordovician.]

Source: US geologic names lexicon (USGS Bull. 1200, p. 1875).

Usage in publication:
- Ion member
Modifications:
- Areal extent
AAPG geologic province:
- Iowa shelf

Publication:

Weiss, M.P., 1955, Some Ordovician brachiopods from Minnesota and their stratigraphic relations: Journal of Paleontology, v. 29, no. 5, p. 759-774., Correction in Jour. Paleo., v. 30, no. 1, p. 219, Jan. 1956

Summary:

Pg. 763. Ion member of Decorah formation. Members of Decorah formation (Spechts Ferry, Guttenberg, and Ion) not recognizable rock units in Minnesota.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1875).

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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).

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