Type area: The Mississinewa Shale Member, originally having formation rank, was named by Cumings and Shrock (1927, p. 72) for shaly weathering argillaceous silty dolostone and dolomitic siltstone, more than 50 ft (15 m) thick in single exposure, along the Mississinewa River between Marion, Grant County, and the southwest corner of Wabash County, north-central Indiana (Shaver, 1970; Droste and Shaver, 1986).
History of usage:
Change in rank: Pinsak and Shaver (1964, p. 35) reduced the rank of the Wabash Formation to that of member in the Wabash Formation (Shaver, 1970; Droste and Shaver, 1986).
In its type area the Mississinewa member consists of argillaceous dolomitic siltstone and silty dolostone, fairly calcareous in places, that is in various shades of gray and is dense to fine grained and massive appearing in unweathered exposures (Droste and Shaver, 1986). Although clay and quartz silt make up more than 50 percent of some samples (Cumings and Shrock, 1928; Erdtmann and Prezbindowski, 1973; Mathews and Sunderman, 1975; Owens, 1981), the designation of the Mississinewa as a shale is incorrect; fissility is notably lacking from fresh exposures and cored sections (Droste and Shaver, 1986). The bottom several to 30 ft (9 m) of the member consists of interbedded and otherwise gradational lithologies of the Mississinewa and Louisville types, the latter consisting of brownish fine-grained dolostone that is purer than the Mississinewa type (Droste and Shaver, 1986). The member also includes subordinate amounts of light-colored granular cherty dolostone and dolomitic limestone of the Liston Creek type (Droste and Shaver, 1986). Bioturbation and other primary sedimentary textures and structures have been described (Erdtmann and Prezbindowski, 1973) as those that occur only in very fine sediments deposited on a generally quiet sea floor (Droste and Shaver, 1986).
The lower Mississinewa contact with the Louisville in southern Indiana and Louisville-equivalent rocks in northern Indiana is conformable and placed at the stratigraphic level (noted above) below which typical Louisville lithology continues downward without intercalation of the Mississinewa type of impurities (Droste and Shaver, 1986). The upper Mississinewa contact with the Liston Creek Limestone Member, although conformable, generally involves fewer transitional rocks than does the lower boundary (Droste and Shaver, 1986). In the type areas of these two Wabash members, for example, the basalmost Liston Creek consists contrastingly of the thin glauconitic Red Bridge Limestone Member. In some other areas, however, the Kokomo Limestone Member (a generally micritic, thinly laminated carbonate rock) or rocks not given member status but having the Kokomo type of lithology overlie the Mississinewa member, probably conformably (Droste and Shaver, 1986). (See, for example, Droste and Shaver, 1982, p. 31, and Shaver and Sunderman, 1983, p. 178.)
In its type-area and in its normal thickness, the Mississinewa correlates with upper Moccasin Springs rocks of the Illinois Basin, with a middle part of the Racine Formation of northern Illinois and eastern Wisconsin, C shale unit (Salina Group) and possibly some subjacent and superjacent Salina rocks in the Michigan and Appalachian Basins, and with a part of the Vernon Shale (Salina Group) of New York (Droste and Shaver, 1986). Where the Mississinewa is at its thickest, however, and occupies nearly all the Wabash interval, these correlations extend appreciably higher stratigraphically (Droste and Shaver, 1986). This means, then, that some upper Mississinewa rocks correlate with some Liston Creek and Kokomo rocks within the Wabash Formation (Droste and Shaver, 1986).
Regional Indiana usage:
Illinois Basin (COSUNA 11)
Geologic Map Unit Designation:
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.
Cumings, E. R., and Shrock, R. R., 1927, The Silurian coral reefs of northern Indiana and their associated strata: Indiana Academy of Science Proceedings, v. 36, p. 71-85.
Cumings, E. R., and Shrock, R. R., 1928, The geology of the Silurian rocks of northern Indiana: Indiana Department of Conservation Publications 75, 226 p.
Droste, J. B., and Shaver, R. H., 1977, Synchronization of deposition–Silurian reef-bearing rocks on Wabash Platform with cyclic evaporites of Michigan Basin, in Fisher, J. H., ed., Reefs and evaporites–concepts and depositional models: American Association of Petroleum Geologists Studies in Geology 5, p. 93-109.
Droste, J. B., and Shaver, R. H., 1986, Mississinewa Shale 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. 93-95.
Erdtmann, B. D., and Prezbindowski, D. R., 1973, Niagaran (Middle Silurian) interreef burial environments, in Seilacher, A., ed., Fossil Lagerstaetten, no. 30: Neues Jahrbuch fuer Geologie und Palaeontologie Abhandlungen, v. 144, p. 342-372.
Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7th ed.): Washington, D.C., U.S. Geological Survey, 289 p.
Indiana University Paleontology Seminar, 1980, Stratigraphy, structure, and zonation of large Silurian reef at Delphi, Indiana: American Association of Petroleum Geologists Bulletin, v. 64, p. 115-131.
Mathews, G. W., and Sunderman, J. A., 1975, Lithologic variability in the Mississinewa Shale and its petrogenetic implications, in Sunderman, J. A., and Mathews, G. W., eds., Silurian reef and interreef environments of northern Indiana: Fort Wayne, Indiana University-Purdue University, p. 54-65.
Owens, R. N., 1981, Petrologic analysis of the Mississinewa Member of the Wabash Formation and the effect of reef proximity on interreef sedimentation: Muncie, Indiana, Ball State University, master's thesis, 83 p.
Rexroad, C. B., Noland, A. V., and Pollock, C. A., 1978, Conodonts from the Louisville Limestone and the Wabash Formation (Silurian) in Clark County, Indiana, and Jefferson County, Kentucky: Indiana Geological Survey Special Report 16, 15 p.
Shaver, R. H., 1970, Mississinewa Shale 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. 111-112.
Shaver, R. H., and Sunderman, J. A., 1983, Silurian reef and interreef strata as responses to a cyclical succession of environments, southern Great Lakes area (Field Trip 12), 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. 141-196.
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.
Shaver, R. H., Doheny, E. J., Droste, J. B., Lazor, J. D., Orr, R. W., Pollock, C. A., and Rexroad, C. B., 1971, Silurian and Middle Devonian stratigraphy of the Michigan Basin–a view from the southwest flank, in Forsyth, J. L., Geology of the Lake Erie islands and adjacent shores: Michigan Basin Geological Society Guidebook, p. 37-59.
Textoris, D. A., and Carozzi, A. V., 1964, Petrography and evolution of Niagaran (Silurian) reefs, Indiana: American Association of Petroleum Geologists Bulletin, v. 48, p. 397-426.
Wood, G. D., 1975, Acritarchs and trilete spores from the Mississinewa Shale of northern Indiana, in Sunderman, J. A., and Mathews, G. W., eds., Silurian reef and interreef environments: Fort Wayne, Indiana University-Purdue University, p. 91-94.
For additional information, contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: April 5, 2017