Age:

Ordovician

Type designation:

Type section: The name Joachim Dolomite was introduced by Winslow in 1894 (p. 331, 352). The unit is exposed along Plattin Creek in Jefferson County, Missouri.

Reference section: Templeton and Willman (1963, p. 55) designated a more complete reference section in the river bluffs between Cape Girardeau and Dutchtown, Cape Girardeau County, Missouri (Droste and Patton, 1986).

Description:

Where fully developed the Joachim consists of three divisions (Droste and Patton, 1986). The lowest unit consists typically of very fine grained to fine-grained argillaceous dark to light-colored dolostone and limestone (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). Thin beds of silty to sandy dolostone and dolomitic fine- to medium-grained sandstone provide evidence for the St. Peter-Joachim facies relationship (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). Where the Joachim overlies the Dutchtown Formation, the darker Joachim rocks grade downward into lighter colored Dutchtown rocks (Droste and Patton, 1986). This part of the Joachim ranges from 0 to 70 ft (0 to 21 m) in thickness (Droste and Patton, 1986).

The middle unit of varicolored limestone and dolostone is the thickest part of the Joachim in Indiana (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). It is purer than the lower and upper units in that it contains fewer sandy, silty, and argillaceous components (Droste and Patton, 1986). The middle Joachim ranges from 0 to 130 ft (0 to 40 m) in thickness (Droste and Patton, 1986).

In local Indiana areas where erosional highs exist on the post-Knox unconformity, the upper part of the Joachim may be the only representative of the Ancell Group between rocks of the Black River Group above and rocks of the Knox Supergroup below (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). These upper rocks contain light-colored to dark silty to very argillaceous and very fine grained to fine-grained dolostone and limestone and interbedded greenish to dark-gray to black shales (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). Thin beds of bimodal sandstone are also present (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). These shaly, silty, and sandy interbeds in the dolostone and limestone of the upper Joachim have led others to designate the upper unit of the Ancell Group as the Glenwood Shale (Droste and Patton, 1986). Because carbonate components dominate in the upper Joachim in Indiana, the term “Glenwood Shale” has been abandoned (Droste and Patton, 1986). The upper part of the Joachim ranges from 0 to 80 ft (0 to 24 m) in thickness (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986).

Distribution: The Joachim Dolomite, exceeding 200 ft (60 m) in thickness in Indiana, has the greatest subsurface distribution of the three formations of the Ancell Group (Droste, Abdulkareem, and Patton, 1982; Droste and Patton, 1986). The only Indiana exposure is in the Kentland structure, Newton County, where the major faulting is along the contact of the St. Peter Sandstone and the Joachim Dolomite (Gutschick, 1983; Droste and Patton, 1986).

Boundaries:

The Joachim Dolomite is the upper formation of the Ancell Group except in a well in extreme northwestern Indiana where the St. Peter constitutes the entire Ancell Group (Droste and Patton, 1986).

Correlations:

The Joachim in Indiana is a lateral equivalent of upper St. Peter rocks in Indiana (Droste and Patton, 1986). Further, it correlates with the Joachim Dolomite of Illinois and Kentucky and with the lowest part of the Black River Limestone of Ohio (as described by Stith, 1979), and it is stratigraphically equivalent to the upper part of the St. Peter Sandstone and of the Glenwood Formation in Illinois and Michigan (Droste and Shaver, 1983; Shaver, 1984; Droste and Patton, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Ancell Group
Formation: Joachim Dolomite
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Ancell Group
Formation: Joachim Dolomite
Cincinnati Arch (COSUNA 13)
Supergroup: none
Group: Ancell Group
Formation: Joachim Dolomite
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Ancell Group
Formation: Joachim Dolomite
Michigan Basin (COSUNA 15)
Supergroup: none
Group: Ancell Group
Formation: Joachim Dolomite

Misc/Abandoned Names:

Glenwood Shale

Geologic Map Unit Designation:

Oj

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:

Droste, J. B., Abdulkareem, T. F., and Patton, J. B., 1982, Stratigraphy of the Ancell and Black River Groups (Ordovician) in Indiana: Indiana Geological Survey Occasional Paper 36, 15 p.

Droste, J. B., and Patton, J. B., 1986, Joachim Dolomite, 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. 66–67.

Droste, J. B., and Shaver, R. H., 1983, Atlas of early and middle Paleozoic paleogeography of the southern Great Lakes area: Indiana Geological Survey Special Report 32, 32 p.

Gutschick, R. C., 1983, Geology of the Kentland Dome structurally complex anomaly–northwestern Indiana (Field Trip 5), in Shaver, R. H., and Sunderman, J. A., eds., Field trips in midwestern geology: Bloomington, Indiana, Geological Society of America, Indiana Geological Survey, and Indiana University Department of Geology, v. 1., p. 105–138.

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.

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.

Stith, D. A., 1979, Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio: Ohio Geological Survey Report of Investigations 113, 36 p.

Templeton, J. S., and Willman, H. B., 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.

Winslow, Arthur, 1894, Lead and zinc deposits: Missouri Geological Survey, v. 6, 387 p.