Springfield Coal Member
Nelson, W.J., 2020, Pennsylvanian Subsystem in Illinois: Illinois State Geological Survey Bulletin (in press).
Edited and figures drafted by Jennifer M. Obrad.
Worthen (1883, p. 6) wrote, “Coal No. 5, or the Springfield coal, is perhaps the most reliable and persistent seam in its development of any in the State.” Worthen noted that seven underground mines were then operating in this bed at Springfield and that numerous boreholes and shafts elsewhere in central and southern Illinois had encountered it. Drawing on another 30 years of mining and drilling activity, Shaw and Savage (1913) presented a more thorough description of the coal in its type area. Coal bed nomenclature in Illinois remained more or less informal until Kosanke et al. (1960) adopted the form Springfield (No. 5) Coal Member. Dual usage of the Springfield and Harrisburg Coals persisted until Jacobson et al. (1985) recommended the name Springfield for basin-wide use.
The coal is named for the capital city of Illinois, where it formerly was mined underground on a large scale. Springfield is one of the most commonplace names in the United States; the U.S. Geological Survey lists 34 populated places named Springfield in 25 states. Indeed, some argued for a less common name when the city was founded in the 1820s. Springfield was chosen because the original settlement lay on Spring Creek and one of the founders hailed from Washington County, Kentucky, where Springfield is the county seat (Callary 2009).
A multitude of names have been applied to this commercial coal seam, the most important in the Illinois Basin. Pioneer geological surveys established No. 5 coal in Illinois, Coal V in Indiana, and No. 9 coal in western Kentucky. The name Harrisburg (No. 5) Coal prevailed in southern Illinois until Jacobson et al. (1985) adopted Springfield for basin-wide usage.
Effectively, there is none. Wanless (1956) and subsequent authors listed sec. 16, T 16 N, R 4 W in Sangamon County and remarked that the coal was “named from subsurface exposures in coal mines” (p. 12). All these mines were sealed decades ago, and no suitable outcrops occur near the capital city.
Core from a hole drilled by the Abandoned Mines Reclamation Council on the east side of Springfield provides a good reference section. The drill site was about 3 mi (5 km) northeast of Springfield in the SW¼ SW¼ NW¼ of sec. 21, T 16 N, R 4 W, Sangamon County (ISGS county no. 23463). The Springfield Coal is in the depth range 245.6 to 251.5 ft; the base was not reached (Figure 4-56). The hole was drilled into Peabody Coal Company’s Mine No. 59, where the Springfield Coal was mined from 1884 to 1951.
The typed core description of the Abandoned Mines Reclamation Council boring is filed at the Geological Records Unit of the ISGS and is available via the ISGS website. Core is archived at the ISGS Geological Samples Library in Champaign under call number C-12799.
In most of the basin, the Springfield Coal rests on well-developed underclay (paleosol), and it directly underlies the black, phosphatic Turner Mine Shale. Close to the Galatia channel, the floor rock is commonly siltstone and the paleosol is less deeply developed. In addition, the gray shale and siltstone of the Dykersburg Member intervene between the coal and the Turner Mine Shale. Within the Galatia channel, the coal laterally intergrades with fine clastic strata.
Extent and thickness
Many authors have mapped this major coal deposit. Comprehensive reports by Treworgy and Bargh (1984) and Treworgy et al. (1999) include statewide maps at 1:500,000 scale. Hatch and Affolter (2002) published (in digital form) a Springfield thickness map that covers the entire Illinois Basin. Together, these authors mapped two large regions of thick Springfield Coal. The map presented here (Figure 4-57) has been modified from Hatch and Affolter (2002). The larger area covers nearly all of the Fairfield Basin in Illinois together with southwestern Indiana and western Kentucky. The coal is 42 in. (107 cm) or thicker across about 80% of this region, and it is consistently 4 to 5 ft (1.2 to 1.5 m) across large areas. Coal 6 ft to more than 10 ft (1.8 to >3.0 m) thick flanks the Galatia channel almost continuously.
The second area of thick coal encompasses north-central Illinois roughly bounded by Springfield, Decatur, Bloomington, and Peoria. The map pattern indicates that a great deal of thick coal was eroded during the late Cenozoic. The Springfield is thinner than 1 ft (30 cm) on most of the Western Shelf except in a small area near the outcrop in Perry and Randolph Counties (Figure 4-57). The coal and the interval between the Springfield and Herrin Coals thin abruptly on the west side of the Du Quoin Monocline, evidence that the monocline rose during Springfield peat accumulation. Other structures where the Springfield thins are the Loudon Anticline and the La Salle Anticlinorium, but not the Salem Anticline. The younger Herrin Coal thins across the La Salle, Loudon, and Salem structures, but not across the Du Quoin Monocline. Curiously, the Springfield thins abruptly south of a line that extends east-southeast from a little south of the city of Springfield. The Herrin Coal thickens south of the same line in nearly reciprocal fashion. The line of abrupt thickness change does not match any known structural feature. Other areas of thin Springfield lie in east-central and northern Illinois (north of Bloomington and Peoria). Thickness changes in these areas seem to be gradual.
Bright-banded coal is prevalent. Neavel (1961) observed that dull bands increase in the upper half of the seam in five columns from mines in Indiana. Hower and Wild (1982) confirmed this observation in more quantitative fashion for samples from 11 mines widely distributed in western Kentucky. The bright coal maceral, vitrinite, constitutes 72 to 79% of the upper one-third of the Springfield Coal compared with 82 to 90% vitrinite in the lower one-third.
No persistent clastic layers are present except close to the Galatia channel, where multiple partings and laminae of carbonaceous shale appear. Still more localized are major “splits” in which wedges of gray shale and siltstone, similar to the overlying Dykersburg, intrude the coal. The manner of splitting suggests large-scale rafting of peat. Coal balls are uncommon and generally occur in isolation. Claystone dikes are abundant in this seam through much of central and northwestern Illinois (Damberger 1970b). In some areas, they were large and numerous enough to impede mining. A high sulfur content of 3 to 5% prevails wherever black shale and limestone lie close to the coal. Low-sulfur coal is confined to areas where the Dykersburg Member is 20 ft (6 m) or thicker (Hopkins 1968).
Both contacts normally are sharp. Occasional cores and mine exposures show coal grading to Dykersburg Shale through a zone of impure coal and carbonaceous shale. The lateral contact to the upper part of the Galatia Member intertongues.
Well log characteristics
Typical for coal.
Brokaw (1942), Kosanke (1950), and Guennel (1952) investigated fossil spores of the Springfield Coal, but the most thorough treatment is in Peppers (1970), who listed almost 90 taxa, the most abundant genera being Laevigatosporites, Lycospora, and Thymospora. Peppers concluded that the Springfield is difficult to differentiate from the older Houchin Creek Coal on the basis of spores, but the younger Briar Hill Coal is distinct from the Springfield.
Mahaffy (1988) investigated the paleoecology of Springfield Coal in the southern Illinois Basin on the basis of palynological samples. Willard (1993) compared palynological profiles to coal-ball profiles collected from the Springfield Coal in southwestern Indiana. Willard et al. (1995) considered the paleoecology of the Springfield and the associated Leslie Cemetery channel by using palynology, macrofloral compression and impression plant fossils, and coal petrography. Paleoecological studies based on fossil plants preserved in Springfield coal balls have been carried out by Phillips and DiMichele (1998) and DiMichele et al. (2002). Many other publications mention fossil plants from this coal in relation to Pennsylvanian peat-forming vegetation and the morphology and taxonomy of plants preserved in coal balls.
Age and correlation
Peppers (1996) placed the Springfield at the top of spore assemblage zone “CP,” which extends from the Dekoven Coal to the Springfield. This position is late Desmoinesian in the Midcontinent, late Westphalian D on the European time scale, and late Moscovian on the global time scale. The Summit Coal of the Midcontinent is directly correlative based on physical stratigraphy (Weller et al. 1942) and palynology (Ravn 1986; Peppers 1996). The Springfield is correlated with the Princess No. 7 coal bed of eastern Kentucky and the Middle Kittanning coal bed of Ohio, West Virginia, and Pennsylvania on the basis of fossil spores (Peppers 1996).
Environments of deposition
See the general discussion of coal in the Introduction.
The Springfield Coal has the largest cumulative production and remaining resources of any coal seam in the Illinois Basin. In Illinois, the Springfield ranks second to the Herrin in past production (2.2 billion tons, 1.99 billion metric tons) and remaining resources (63 billion tons, 57 billion metric tons; Treworgy et al. 1999). The Springfield leads in both categories in western Kentucky (Weisenfluh 2010). In Indiana, the Springfield leads in past production but trails the Seelyville Coal in remaining resources (Mastalerz et al. 2009).
- Brokaw, A.L., 1942, Spores from Coal No. 5 (Springfield-Harrisburg) in Illinois: Urbana, University of Illinois, M.S. thesis, 28 p.
- Callary, E., 2009, Place names of Illinois: Urbana, University of Illinois Press, 425 p.
- Damberger, H.H., 1970b, Clastic dikes and related impurities in Herrin (No. 6) and Springfield (No. 5) Coals of the Illinois Basin: Illinois State Geological Survey, Guidebook 8, p. 111–119.
- DiMichele, W.A., T.L. Phillips, and W.J. Nelson, 2002, Place vs. time and vegetational persistence: A comparison of four tropical mires from the Illinois Basin during the height of the Pennsylvanian Ice Age: International Journal of Coal Geology, v. 50, no. 1, p. 43–72.
- Guennel, G.K., 1952, Fossil spores of the Alleghenian coals in Indiana: Indiana Geological Survey, Bulletin 13, 101 p.
- Hatch, J.R., and R.H. Affolter, 2002, Resource assessment of the Springfield, Herrin, Danville, and Baker Coals in the Illinois Basin: U.S. Geological Survey, Professional Paper 1625-D, version 1.0, https://pubs.usgs.gov/pp/1625d/report.pdf (accessed October 2, 2020).
- Hopkins, M.E., 1968, Harrisburg (No. 5) Coal reserves of southeastern Illinois: Illinois State Geological Survey, Circular 431, 25 p., 2 pls.
- Hower, J.C., and G.D. Wild, 1982, Petrographic variation in the Springfield (No. 9) coal in western Kentucky: International Journal of Coal Geology, v. 2, p. 17–30.
- Jacobson, R.J., C.B. Trask, C.H. Ault, D.D. Carr, H.H. Gray, W.A. Hasenmueller, D. Williams, and A.D. Williamson, 1985, Unifying nomenclature of the Pennsylvanian System in the Illinois Basin: Transactions of the Illinois Academy of Science, v. 78, no. 1–2, p. 1–11.
- Kosanke, R.M., 1950, Pennsylvanian spores of Illinois and their use in correlation: Illinois State Geological Survey, Bulletin 74, 128 p., 2 pls.
- Kosanke, R.M., J.A. Simon, H.R. Wanless, and H.B. Willman, 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey, Report of Investigations 214, 84 p. and 1 pl.
- Mahaffy, J.F., 1988, Vegetational history of the Springfield Coal (Middle Pennsylvanian of Illinois) and distribution patterns of a tree-fern miospore, Thymospora pseudothiessenii, based on miospore profiles: International Journal of Coal Geology, v. 10, no. 3, p. 239–259.
- Mastalerz, M., A. Drobniak, J.A. Rupp, and N.R. Shaffer, 2009, Characterization of Indiana’s coal resource: availability of the reserves, physical and chemical properties of the coal, and present and potential uses: Indiana Geological Survey, Special Report 66, 214 p., CD-ROM.
- Neavel, R.C., 1961, Petrographic and chemical composition of Indiana coals: Indiana Geological Survey, Bulletin 22, 81 p., 6 pls.
- Peppers, R.A., 1970, Correlation and palynology of coals in the Carbondale and Spoon Formations (Pennsylvanian) of the northeastern part of the Illinois Basin: Illinois State Geological Survey, Bulletin 93, 173 p.
- 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, 111 p. and correlation chart.
- Phillips, T.L., and W.A. DiMichele, 1998, A transect through a clastic-swamp to peat-swamp ecotone in the Springfield Coal, Middle Pennsylvanian age of Indiana, USA: Palaios, v. 13, no. 2, p. 113–128.
- Ravn, R.L., 1986, Palynostratigraphy of the Lower and Middle Pennsylvanian coals of Iowa: Iowa Geological Survey, Technical Paper No. 7, 245 p.
- Shaw, E.W., and T.E. Savage, 1913, Tallula and Springfield folio: U.S. Geological Survey, Geologic Atlas of the United States, Folio No. 188, 12 p. and 6 maps, 1:62,500.
- Treworgy, C.G., and M.H. Bargh, 1984, Coal resources of Illinois: Illinois State Geological Survey, 6 maps, 1:500,000.
- Treworgy, C.G., C.P. Korose, C.A. Chenoweth, and D.L. North, 1999, Availability of the Springfield Coal for mining in Illinois: Illinois State Geological Survey, Illinois Minerals 118, 43 p., 3 pls.
- Wanless, H.R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey, Circular 217, 14 p.
- Weisenfluh, G.A., 2010, Remaining resources of the Springfield Coal: Kentucky Geological Survey, Map and Chart 197, 1 sheet, 1:225,000.
- Weller, J.M., H.R. Wanless, L.M. Cline, and D.G. Stookey, 1942, Interbasin Pennsylvanian correlations, Illinois and Iowa: American Association of Petroleum Geologists Bulletin, v. 26, p. 1585–1593.
- Willard, D.A., 1993, Vegetational patterns in the Springfield Coal (Middle Pennsylvanian, Illinois Basin): comparison of miospore and coal-ball records: Geological Society of America, Special Paper 286, p. 139–152.
- Willard, D.A., W.A. DiMichele, D.L. Eggert, J.C. Hower, C.B. Rexroad, and A.C. Scott, 1995, Paleoecology of the Springfield Coal Member (Desmoinesian, Illinois Basin) near the Leslie Cemetery paleochannel, southwestern Indiana: International Journal of Coal Geology, v. 27, no. 1, p. 59–98.
- Worthen, A.H., 1883, Geology and palaeontology: Geological Survey of Illinois, v. 7, 373 p., 31 pls.
|Stratigraphic Code||Geo Unit Designation|