Age:

Pennsylvanian

Type designation:

Type section: The name “Velpen Coal” was used by Fuller and Ashley (1902) for the coal in Pike County, Indiana, now known as the Colchester Coal Member of the Linton Formation (Burger and Wier, 1970, p. 182-183; Burger, Wier, and Ault, 1986). The name “Velpen Limestone Member” was adopted as a member of the Linton Formation, and its type section was designated in the NE¼SE¼NE¼ sec. 8, T. 2 S., R. 6 W., 0.5 miles (.8 km) northeast of Velpen in Pike County (Burger and Wier, 1970, p. 182-183; Burger, Wier, and Ault, 1986).

Reference core: A reference core from Indiana Geological Survey drill hole (SDH) 306 (Indiana Geological Survey Petroleum Database Management System No. 115871) contains the Velpen Limestone Member from 133.4 to 136.8 ft (40.7 to 41.7 m) (Hasenmueller and Ault, 1991, p. 7). SDH 306 is located in the SE¼NE¼NW¼ sec. 2, T. 2 S., R. 7 W., near the type section of the Survant Coal Member of the Linton Formation in Pike County (Hasenmueller and Ault, 1991, fig. 1).

History of usage:

The name “Velpen” was used by Weller, Henbest, and Dunbar (1942, p. 32) for the cap rock of the Colchester Coal Member and by Cooper (1946, p. 16) and Zangerl and Richardson (1963, p. 28) for the limestone above the coal (Burger and Wier, 1970; Burger, Wier, and Ault, 1986).

Description:

The Velpen Limestone Member is a variable unit, generally tan to black, dense, and argillaceous, containing small crinoid columnals and ranging from 0.1 to 4.5 ft (<0.1 to 1.4 m) in thickness (Burger and Wier, 1970; Burger, Wier, and Ault, 1986). The Velpen consists variably of black dense, sparsely fossiliferous limestone, brownish-gray, finely crystalline limestone containing abundant brachiopods and crinoid fragments, calcareous fossiliferous shale, and nonfossiliferous argillaceous siderite (Burger and Wier, 1970; Burger, Wier, and Ault, 1986). It generally rests on black shale, which separates it from the underlying Colchester Coal Member, and underlies gray or black shale (Burger and Wier, 1970; Burger, Wier, and Ault, 1986).

Rexroad and others (2001) suggested that in west-central Indiana the Velpen Limestone Member of the Linton Formation was deposited in more open marine waters than the underlying Mecca Quarry Shale Member of the Linton Formation.

Distribution: The Velpen is recognizable in the outcrop wherever the Colchester can be identified (Burger and Wier, 1970; Burger, Wier, and Ault, 1986). The Velpen may not be recognized in the subsurface on geophysical logs because of its thinness, but its position can usually be inferred from the position of the Colchester, which can be recognized on most logs (Burger, Wier, and Ault, 1986).

Correlations:

Rexroad and others (2001) assigned the fauna from the Mecca Quarry Shale Member and the Velpen Limestone Member to the Neognathodus roundyi zone, which is appreciably younger than the Ardmore Member of the Verdigris Formation in Missouri and the Verdigris Member of the Sonora Formation of Oklahoma, units with which the Velpen had been correlated. The Oak Grove Limestone Member of the Carbondale Formation in northern Illinois is slightly older than the Velpen (Rexroad and others, 2001).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Carbondale Group
Formation: Linton Formation
Member: Velpen Limestone Member
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Carbondale Group
Formation: Linton Formation
Member: Velpen Limestone Member

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

*lv

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:

Burger, A. M., Wier, C. E., 1970, Velpen 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. 182–183.

Burger, A. M., Wier, C. E., and Ault, C. H., 1986, Velpen 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. 160.

Cooper, C. L., 1946, Pennsylvanian ostracodes of Illinois: Illinois State Geological Survey Bulletin 70, 177 p.

Fuller, M. L., and Ashley, G. H., 1902, Description of the Ditney quadrangle: U.S. Geological Survey Geologic Atlas, Folio 84, 8 p.

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.

Hasenmueller, W. A., and Ault, C. H., 1991, Reference core and correlation of key beds in the Petersburg and Linton Formations (Pennsylvanian) in Indiana: Indiana Geological Survey Occasional Paper 57, 8 p.

Rexroad, C. B., Wade, J. A., Merrill, G. K., Brown, L. M., and Padgett, P., 2001, Conodont biostratigraphy and depositional environments of the Mecca Quarry Shale Member and the Velpen Limestone Member of the Linton Formation (Pennsylvanian, Desmoinesian) in the eastern part of the Illinois Basin, U.S.A.: Indiana Geological Survey Special Report 63, 19 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.

Weller, J. M., Henbest, L. G., and Dunbar, C. O., 1942, Stratigraphy of the fusuline-bearing beds of Illinois, in Dunbar, C. O., and Henbest, L. G., Pennsylvanian Fusulinidae of Illinois: Illinois State Geological Survey Bulletin 67, p. 9–34.

Zangerl, Rainer, and Richardson, E. S., Jr., 1963, The paleoecological history of two Pennsylvanian black shales: Fieldiana, Geology Memoirs, v. 4, 352 p.