Age:

Pennsylvanian

Type designation:

Type section: The Perth Limestone Member was named by Hutchison (1960, p. 19-21) for exposures in the abandoned surface mine in the SW¼NE¼ sec. 3, T. 13 N., R. 7 W., near Perth, Clay County, Indiana (Hutchison, 1970, 1986).

History of usage:

In Clay County and in adjacent counties this limestone had earlier been known as the Minshall Limestone (Hutchison, 1970, 1986). The name “Minshall” had also been mistakenly applied to other limestones and coals (Hutchison, 1970, 1986). The Perth lies 0.2 ft to 15 ft (0.06 to 4.6 m) above the Minshall Coal Member (Hutchison, 1970, 1986).

Description:

At the type locality the limestone is gray, hard, argillaceous, and fossiliferous (Hutchison, 1970, 1986). It weathers brown and contains a 2-ft-thick (0.6-m) medial band of blue chert that is hard, fossiliferous, and vuggy (Hutchison, 1970, 1986). The limestone is not continuously present and varies considerably in character and ranges from 0.5 ft to 19 ft (0.2 to 5.8 m) in thickness (Hutchison, 1970, 1986). Where absent, its position is occupied by gray shale that is soft, calcareous in places, and fossiliferous or by gray to brown sandstone that is fine to medium grained and is calcareous in places (Hutchison, 1970, 1986).

Distribution: The Perth or a limestone of similar stratigraphic position has been recognized from central Warren County southward to the Ohio River (Hutchison, 1970, 1986). In southern Indiana the Perth seems to correspond closely to the limestone above the Buffaloville Coal Member, and drilling records indicate that a limestone of similar or identical position is present in the subsurface of most of the counties of southwestern Indiana (Hutchison, 1970, 1986).

Correlations:

Understanding the Perth correlation is complicated by the substitution of this name for the ambiguously used term "Minshall"; in the guise of the older name, the Perth has been correlated as low as the Lead Creek Limestone Member and as high as the Curlew Limestone Member of western Kentucky (Hutchison, 1970, 1986). The Perth (old Minshall in part) lies below the lowest position of the fusulinid Wedekindellina, which is found in what at times has been called the Minshall Limestone (Thompson and Shaver, 1964, p. 21; Shaver and Smith, 1974, p. 12, 17; Hutchison, 1986). Hutchison (1970, 1986) noted that the Perth and the limestone above the Buffaloville Coal Member do mark the lowest known Indiana position of the ostracod fauna characterized by Amphissites centronotus and A. girtyi, and it is a limestone close above the highest known Profusulinella and ostracods of the Amphissites rothi fauna. Collectively, the Perth microfauna is generally similar to that in the Seville Limestone Member of western Illinois, the Lower Mercer Limestone of Ohio, and the Curlew Limestone Member of the Tradewater Formation of western Kentucky (Hutchison, 1970, 1986). But a Kentucky limestone that is also a possible correlative is the limestone, possibly lower than the Curlew, containing Fusulinella and associated with what has been called the Lewisport Coal that was mined near Lewisport, Daviess County, Kentucky (Hutchison, 1970, 1986). On the basis of this microfauna, the Perth was assigned to the Desmoinesian Series (Shaver and Smith, 1974; Shaver, 1984; Hutchison, 1986).

Rexroad and others (1998) reported that the Perth Limestone Member of Indiana and Curlew Limestone Member of Kentucky have a moderately variable but predictable conodont fauna dominated by Idiognathodus. Both units are in the Neognathodus bothrops-N. bassleri Subzone and correlate approximately with the Seville in northwestern Illinois and with the interval between the Lower and Upper Mercer limestones in Ohio (Rexroad and others, 1998). As noted above, in Indiana the base of the Desmoinesian has been placed slightly below the Perth, and the Perth conodonts are compatible with this age; however, Peppers (1996), on the basis of palynological and fusulinid data, placed the boundary at the top of the Perth-Curlew-Seville complex (Rexroad and others, 1998). Rexroad and others (1998) were unable to confirm the assignment of the Perth to earliest Desmoinesian as opposed to latest Atokan.

The Tri-State Commission on Correlation of the Pennsylvanian System in the Illinois Basin (2001) placed the base of the Desmoinesian Series below the Perth.

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Raccoon Creek Group
Formation: Staunton Formation
Member: Perth Limestone Member
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Raccoon Creek Group
Formation: Staunton Formation
Member: Perth Limestone Member

Misc/Abandoned Names:

Minshall Limestone

Geologic Map Unit Designation:

*stp

Note: Hansen (1991, p. 52) in Suggestions to authors of the reports of the United States Geological Survey noted that letter symbols for map units are considered to be unique to each geologic map and that adjacent maps do not necessarily need to use the same symbols for the same map unit. Therefore, map unit abbreviations in the Indiana Geologic Names Information System should be regarded simply as recommendations.

COSUNA areas and regional terminology

Names for geologic units vary across Indiana. The Midwestern Basin and Arches Region COSUNA chart (Shaver, 1984) was developed to strategically document such variations in terminology. The geologic map (below left) is derived from this chart and provides an index to the five defined COSUNA regions in Indiana. The regions are generally based on regional bedrock outcrop patterns and major structural features in Indiana. (Click the maps below to view more detailed maps of COSUNA regions and major structural features in Indiana.)

COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural features in Indiana.

Major tectonic features that affect bedrock geology in Indiana.

References:

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7^th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Hutchison, H. C., 1960, Geology and coal deposits of the Brazil quadrangles, Indiana: Indiana Geological Survey Bulletin 16, 38 p.

Hutchison, H. C., 1970, Perth Limestone Member, in Shaver, R. H., Burger, A. M., Gates, G. R., Gray, H. H., Hutchison, H. C., Keller, S. J., Patton, J. B., Rexroad, C. B., Smith, N. M., Wayne, W. J., and Wier, C. E., Compendium of rock-unit stratigraphy in Indiana: Indiana Geological Survey Bulletin 43, p. 131–132.

Hutchison, H. C., 1986, Perth Limestone Member, in Shaver, R. H., Ault, C. H., Burger, A. M., Carr, D. D., Droste, J. B., Eggert, D. L., Gray, H. H., Harper, Denver, Hasenmueller, N. R., Hasenmueller, W. A., Horowitz, A. S., Hutchison, H. C., Keith, B. D., Keller, S. J., Patton, J. B., Rexroad, C. B., and Wier, C. E., Compendium of Paleozoic rock-unit stratigraphy in Indiana–a revision: Indiana Geological Survey Bulletin 59, p. 111–112.

Peppers, R. A., 1996, Palynological correlation of major Pennsylvanian (Middle and Upper Carboniferous) chronostratigraphic boundaries in the Illinois and other coal basins: Geological Society of America Memoir 188, p. 1–111.

Rexroad, C. B., Brown, L. M., Devera, Joe, and Suman, R. J., 1998, Conodont biostratigraphy and paleoecology of the Perth Limestone Member, Staunton Formation (Pennsylvanian) of the Illinois Basin, U.S.A., in Szaniawski, Hubert, ed., Proceedings of the Sixth European Conodont Symposium (ECOS VI): Palaeontologia Polonica, v. 58, p. 247–259.

Shaver, R. H., and Smith, S. G., 1974, Some Pennsylvanian kirkbyacean ostracods of Indiana and midcontinent series terminology: Indiana Geological Survey Report of Progress 31, 59 p.

Shaver, R. H., coordinator, 1984, Midwestern basin and arches region–correlation of stratigraphic units in North America (COSUNA): American Association of Petroleum Geologists Correlation Chart Series.

The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin, 2001, Toward a more uniform stratigraphic nomenclature for rock units (formations and groups) of the Pennsylvanian System in the Illinois Basin: Indiana Geological Survey, Illinois Basin Consortium Illinois Basin Studies 5, 26 p.

Thompson, M. L., and Shaver, R. H., 1964, Early Pennsylvanian microfaunas of the Illinois Basin: Illinois State Academy of Science Transactions, v. 67, no. 1, p. 1–23.