Illinois Basin

Location

See text below

References

(selected) J. Weller 1936, J. Weller and Bell 1937, Clark and Royds 1948, Swann and Bell 1958, Eardley 1962, Wanless 1962, Snyder 1968, Bond et al. 1971, Willman et al. 1975, King 1977, Palmer and Dutcher 1979, Treworgy and Whitaker 1990a, b, Whitaker and Treworgy 1990, Leighton et al. 1991, Whitaker et al. 1992, Treworgy et al. 1994

Description

The Illinois Basin, also called the Eastern Interior Basin, is bordered on the southwest by the Ozark Dome. On the west, it is separated from the Forest City Basin by the Mississippi River Arch and the Missouri portion of the Lincoln Anticline. Northward it abuts the Wisconsin Arch. To the northeast, the Kankakee Arch separates it from the Michigan Basin; and to the east and southeast, the Cincinnati Arch divides it from the Appalachian Basin. Southern closure of the Illinois Basin was effected by uplift of the Pascola Arch that subsequently was beveled by pre-Late Cretaceous erosion and overlapped by rocks of the Mississippi Embayment fill.

The term Eastern Interior Basin has various connotations. For many geologists it is the same as the Illinois Basin. Wanless (1962) used Eastern Interior Basin for the larger feature and applied the name Illinois Basin to what is now called the Fairfield Basin. The term Eastern Interior also has been applied to both the Illinois and Michigan Basins (Snyder 1968).

The boundaries of the Illinois Basin are somewhat arbitrary. In most places, the basin grades almost imperceptibly into the adjacent domes and arches. The extent of the Pennsylvanian System commonly is taken as the limit by those interested in coal; but when the focus is on petroleum, the extent of the Chesterian Series or the Devonian New Albany Group frequently is used. Another boundary that has been used is the -500 foot (-150 m) elevation contour of the top of the Galena Group (Trenton). According to most of these definitions, the Illinois Basin covers three-quarters of Illinois, west-central and southwestern Indiana, and part of western Kentucky. Small adjacent areas of lowa, Missouri, and Tennessee fall within some versions of the boundaries.

The definitive work on the Illinois Basin is Leighton et al. (1991 ), which contains more than 500 pages of text on geology and petroleum in this basin.