Age:
Silurian
Type designation:
Type area: The type area of the Wabash Formation is in that part of the upper Wabash Valley extending from Carroll County to Huntington County, Indiana (Droste and Shaver, 1986).
Principal reference sections: Five principal reference sections were designated by Pinsak and Shaver (1964, Table 5).
(1) The most complete reference section consisted of rocks cored in the Northern Indiana Public Service Co. Gale M. and Glada Skinner No. 1 well (Indiana Geological Survey Petroleum Database Management System No. 134550) near Royal Center, Cass County, Indiana (NW¼NW¼ sec. 10, T. 28 N., R. 1 W.). Mississinewa and Liston Creek Limestone Members.
(2) Exposure in the road cut of Indiana Highway 13 at the south edge of the city of Wabash and south of the Wabash River, Wabash County, Indiana (N½ J. B. Richardville Reserve No. 8, T. 27 N., R. 6 E.). Mississinewa and Liston Creek Limestone Members.
(3) Big Four Railroad cut in Wabash, Wabash County, Indiana. Mississinewa Shale Member and reef (Huntington Lithofacies).
(4) Erie Stone Co. quarry just east of Huntington, Huntington County, Indiana. (SE¼ sec. 12, T. 28 N., R. 9 E.). Huntington Lithofacies and other rocks associated with reef development.
(5) May Stone and Sand, Inc., quarry, southwest edge of Fort Wayne, Allen County, Indiana. (NW¼ sec. 29, T. 30 N., R. 12 E.). Huntington Lithofacies in Fort Wayne Bank.
History of usage:
The Wabash Formation was named in 1964 for all then so-called "Niagaran" rocks in northern Indiana lying above the Louisville Limestone and exclusive of Silurian rocks then assigned to the Salina Formation (Pinsak and Shaver, 1964, p. 34-47; Droste and Shaver, 1986). This definition included the preexisting units called the Mississinewa Shale, the Liston Creek Limestone, the New Corydon Limestone (nontypical, of Cumings and Shrock, 1928a, p. 113-117), and the Noblesville Dolomite (obsolete at that time, of Kindle and Breger, 1904, p. 407) (Droste and Shaver, 1986).
After considerable post-1964 evidence had accumulated to show that appreciable facies relationship exists between the Wabash and Salina Formations, the Wabash definition was expanded to include the upper part of the Salina Formation as previously defined, and the Salina was given group status to include the Wabash and older rocks in northern Indiana down through the Louisville Limestone and the Limberlost Dolomite (Droste and Shaver, 1982; Droste and Shaver, 1986). Before that time, however, Becker (1974), Becker and Droste (1978), Rexroad, Noland, and Pollock (1978), and Droste and Shaver (1980) had defined the southern Indiana occurrence to extend very nearly to the southeastern Silurian outcrop, there being narrowly overlapped in the subsurface by Middle Devonian rocks, and well into the Illinois Basin, there being terminated along a defined vertical cutoff against rocks of the middle and upper parts of the Bainbridge Group (Droste and Shaver, 1986). This cutoff leaves an area of about eight-county size unoccupied by Wabash rocks (as defined) in the southwest corner of Indiana (Droste and Shaver, 1986).
As noted above, the Wabash in northern Indiana is assigned to the Salina Group, which has a defined southwestern vertical cutoff boundary extending northwestward from eroded edges in central eastern Indiana and, farther on, northward to northwestern Indiana (Droste and Shaver, 1986). Outside (west and south of) this boundary, the Wabash is not assigned to a group (Droste and Shaver, 1986).
Description:
Four principal lithologies that intergrade and replace one another spatially characterize the Wabash Formation: (1) calcareous silty dolostone and dolomitic silty limestone that are gray, dense to fine grained, and massive (when fresh) and that are characteristic of, but not confined to, the Mississinewa Shale Member in the lower part of the formation; (2) limestone, dolomitic limestone, and dolostone that are light colored, mostly finely granular, cherty but otherwise fairly pure, and slabby bedded (in weathered exposures) and that are characteristic of, but not confined to, the upper part of the formation, especially the Liston Creek Limestone Member and less so the Kenneth Limestone Member; (3) dolostone and dolomitic limestone that are generally in shades of light tan to dark brown (but including grayish and greenish colors), are generally micritic to fine grained, are generally nonfossiliferous, and become strikingly color banded and thinly laminated over broad areas and that are characteristic of the Kokomo Limestone Member and especially of the upper Wabash rocks (unnamed to member) in the northern two tiers of Indiana counties; some greenish shale is included in the latter lithology in those northern counties; and (4) light-colored granular massive vuggy, nearly pure dolostone and limestone and bluish-gray carbonate mudstone that are widely distributed in bank, reef, reef-detrital, and biohermal facies throughout much of the formation (Droste and Shaver, 1986).
The latter lithology has been widely referred to as the Huntington Lithofacies (not a rock- stratigraphic term and not confined to the Wabash) as first recommended by Pinsak and Shaver (1964, p. 39-40), partly as a salvage expedient for the classic but misused term "Huntington Dolomite (Limestone, Stone)" (Droste and Shaver, 1986). The reef facies within the Wabash exists in probably thousands of modest-sized to very large so-called patch reefs and pinnacle reefs and in barrierlike, but yet poorly understood, features called the Fort Wayne Bank (marginal to the Michigan Basin) and the Terre Haute Bank (marginal to the Illinois Basin) (Droste and Shaver, 1986). (See descriptions, including actual depictions, of such features in Cumings and Shrock, 1928; Shaver and others, 1978; Droste and Shaver, 1980, 1982.) At least part of such features are made up of the upper, coalesced parts of reefs that are discrete in their lower parts (Droste and Shaver, 1986). The reef facies in southwestern Indiana and adjacent Illinois includes the thickest Silurian reef deposits known in the United States. Some are nearly 1,000 ft (305 m) thick, but part of that thickness is in the pre-Wabash stratigraphic interval (Lowenstam, 1949; Becker and Droste, 1978; Bristol, 1974; Droste and Shaver, 1980; and Droste and Shaver, 1987; Droste and Shaver, 1986).
The Wabash Formation is underlain conformably by the Louisville Limestone (Droste and Shaver, 1986). The boundary is placed at the bottom of a thick transitional interval (Rexroad, Noland, and Pollock, 1978, p. 2), or it is underlain in similar manner by the Pleasant Mills Formation (Droste and Shaver, 1986). The difference is only a defined difference in names (Droste and Shaver, 1986). (See the Pleasant Mills [also Salina] limit line in fig. 6 of Droste and Shaver, 1982). The Wabash, where present, underlies nearly everywhere the Muscatatuck Group (mostly Middle Devonian) unconformably (Droste and Shaver, 1986). Possibly in farthest northeastern Indiana the Wabash underlies even older Lower Devonian rocks, although such rocks are presently included in the Muscatatuck Group (Droste and Shaver, 1986). Some Wabash rocks, including reef rocks, along the defined Wabash cutoff in far southwestern Indiana underlie the New Harmony Group (Lower Devonian), possibly both conformably and unconformably (Droste and Shaver, 1986).
Distribution: The Wabash Formation ranges in thickness from zero along its southeastern eroded edge to a regional (nonreef) thickness of more than 400 ft (122 m) in southwestern Indiana, to about 250 ft (76 m) in central western Indiana, to more than 400 ft (122 m) in the Newton County area (northwestern Indiana), and to 200 ft (61 m) in northeasternmost Indiana (Droste and Shaver, 1986).
Correlations:
The hundreds of classically studied macrofossils from Wabash reef and interreef rocks have been assigned stratigraphically secure positions (Shaver, 1974). Among those to which greatest biostratigraphic importance may be attached are the pentamerid brachiopods Kirkidium cf. K. knighti (low in the formation) and K. cf. K. laqueatum (high in the formation), the graptolite Monograptus falciformis (= M. bohemicus; low in the formation), and the mollusk Megalomus canadensis (known high in the formation but probably has a lower range to below the formation) (Droste and Shaver, 1986).
Microfossil studies have recorded conodont taxa that are considered to be elements of zones ranging upward from within the Zone of Kockelella to within the Zone of Ozarkodina eosteinhornensis (Droste and Shaver, 1986). The acritarch zone characterized by Deunffia eisenacki has been identified in lower Wabash rocks. Ostracod species identified as Dizygopleura hallii and Thlipsurella parva and associated species are found very high in the formation (Droste and Shaver, 1986).
These fossils collectively indicate an age ranging from within Ludovian time into Pridolian (late Niagaran to possibly very late Cayugan) (Droste and Shaver, 1986).
Physical tracing, sequential stratigraphy, and geophysical logging yield other correlative evidence, so that the evidence of all kinds supports these approximate to close correlations: deeper part of the Illinois Basin in Indiana, Kentucky, and Illinois, much of the Moccasin Springs Formation through the Bailey Limestone; northern Illinois, middle part of the Racine Formation through all the Racine that is uneroded; Michigan Basin, from either the B salt (unit) or C unit of the Salina Group to as high as the G unit and possibly even as high as the overlying Bass Islands Group; south-central Kentucky and adjacent Tennessee, the Dixon Formation through the Decatur Limestone; and New York, from within the Vernon Shale (Salina Group) probably to Silurian formations above the Salina Group (Droste and Shaver, 1986).
Economic Importance:
Industrial Minerals: Crushed stone products from the Wabash Formation (Silurian) include the following: aglime, base materials, crushed stone, crushed and sized limestone, crushed stone for Portland masonry cement production, dolomite limestone, fill materials, high-calcium limestone, hot and cold mix asphalt, pugmill material, riprap, and manufactured sand from quarries in Allen, Carroll, Clark, Grant, Huntington, Jasper, Lake, Miami, Pulaski, Wells, and White Counties (Shaffer, 2016).
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References:
Becker, L. E., 1974, Silurian and Devonian rocks in Indiana southwest of the Cincinnati Arch: Indiana Geological Survey Bulletin 50, 83 p.
Becker, L. E., and Droste, J. B., 1978, Late Silurian and Early Devonian sedimentologic history of southwestern Indiana: Indiana Geological Survey Occasional Paper 24, 14 p.
Bristol, H. M., 1974, Silurian pinnacle reefs and related oil production in southern Illinois: Illinois State Geological Survey Illinois Petroleum 102, 98 p.
Cumings, E. R., and Shrock, R. R., 1928, Niagaran coral reefs of Indiana and adjacent states and their stratigraphic relations: Geological Society of America Bulletin, v. 39, p. 579–620.
Cumings, E. R., and Shrock, R. R., 1928, The geology of the Silurian rocks of northern Indiana: Indiana Department of Conservation Publication No. 75, 226 p.
Droste, J. B., and Shaver, R. H., 1980, Recognition of buried Silurian reefs in southwestern Indiana: Journal of Geology, v. 88, p. 567–587.
Droste, J. B., and Shaver, R. H., 1982, The Salina Group (Middle and Upper Silurian) of Indiana: Indiana Geological Survey Special Report 24, 41 p.
Droste, J. B., and Shaver, R. H., 1986, Wabash Formation, 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. 163–165.
Droste, J. B., and Shaver, R. H., 1987, Upper Silurian and Lower Devonian stratigraphy of the central Illinois Basin: Indiana Geological Survey Special Report 39, 29 p.
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.
Lowenstam, H. A., 1949, Niagaran reefs in Illinois and their relation to oil accumulation: Illinois State Geological Survey Report of Investigations 145, 36 p.
Pinsak, A. P., and Shaver, R. H., 1964, The Silurian formations of northern Indiana: Indiana Geological Survey Bulletin 32, 87 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.
Shaffer, K. R., compiler, 2016, Directory of industrial mineral producers in Indiana: Indiana Geological Survey Directory 11-2016, 287 p.
Shaver, R. H., 1974, The Niagaran (Middle Silurian) macrofaunas of northern Indiana–review, appraisal, and inventory: Indiana Academy of Science Proceedings, v. 83, p. 301–315.
Shaver, R. H., Ault, C. H., Ausich, W. I., Droste, J. B., Horowitz, A. S., James, W. C., Okla, S. M., Rexroad, C. B., Suchomel, D. M., and Welch, J. R., 1978, The search for a Silurian reef model–Great Lakes area: Indiana Geological Survey Special Report 15, 36 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.
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