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Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 253, part 1
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Palynological Correlations in the Midcontinent

Most of the coals in the midcontinent region that have been palynologically investigated are Desmoinesian in age because they are the most extensive and are of most economic importance. Wilson and Coe (1940), Wilson and Kosanke (1944), and Wilson (1958) described several new palynomorph taxa from the Desmoinesian of Iowa. Wilson and Hoffmeister (1956) and Wilson (1964) reported on palynology of the Croweburg coal bed, which correlates with the Colchester (No. 2) Coal Member in the Illinois basin. Palynology of the coals in the Cabaniss Group in Oklahoma and equivalent rocks in Kansas was briefly outlined in order to ascertain whether spores could be used to differentiate the coal beds (Wilson and Hoffmeister, 1958).

Students of L. R. Wilson have studied palynology of a number of coal beds in Oklahoma while he was associated with the University of Oklahoma and the Oklahoma Geological Survey. The paleobotanical development and succession of spore assemblages in the coals were emphasized. Most of these theses or dissertations have not been published except for Morgan's (1955) work on the McAlester, Stigler, Rowe, and Riverton coal beds. These unpublished studies describe the palynology of the following coal beds: the Secor (Clarke, 1961), Weir-Pittsburg (Higgins, 1961; Bond, 1963), Ironpost (Gibson, 1961), Rowe (Davis, 1961), Tebo (Ruffin, 1961), Mineral (Urban, 1962), McAlester (Dempsey, 1964), Drywood (Bordeau, 1964), Drywood and Bluejacket (Urban, 1965), and Bevier (Dolly, 1965). Many of these theses attempted to correlate the coals in Oklahoma with those in the Illinois basin based mainly on Kosanke's 1950 study. Wilson (1976a) used these theses to briefly summarize the palynology of Desmoinesian coals in northeastern Oklahoma. Elsewhere, Jones (1957) in his thesis at the University of Missouri, reported on the palynology of the Bevier coal in Missouri, and Rosowitz (1982) at Wichita State University reported on the palynology of the Riverton coal in Kansas.

Several earlier palynological investigations centered on placing the Desmoinesian-Missourian boundary in the midcontinent (Wilson, 1979b, 1984; Wilson and Bennison, 1981). Pearson (1975), while at the University of Oklahoma, studied the palynology of the Seminole coals in Oklahoma, which are early Missourian in age. Simpson (1969) at the University of Tulsa also wrote his thesis on the palynology of some Missourian strata in Tulsa County, Oklahoma.

Several studies of Early Pennsylvanian palynomorphs in the western part of the midcontinent also have been made. Felix and Burbridge (1967) described spores in the Springer Formation in Oklahoma, which is transitional between Mississippian and Pennsylvanian. Owens et al. (1984) and Loboziak et al. (1984) reported on spores in Mississippian and Lower Pennsylvanian strata in northern Arkansas and correlated the assemblages with those in Europe. Peppers (1996) described the spore content of the Baldwin coal bed, which is in the Bloyd Formation. Wilson (1965) reported on a spore assemblage from shale overlying the Springer Formation at Ti Valley, Pittsburg County, Oklahoma. He determined that the assemblage is Morrowan in age but that the assemblage contained recycled late Mississippian spores. Palynology of some Morrowan coal beds in eastern Iowa, which are within a westward extension of the Illinois basin, were studied by Ravn and Fitzgerald (1982).

Earliest reference to the rocks comprising the Cherokee Group in Kansas was by Haworth and Kirk (1894), who named the unit Cherokee shales for the Cherokee County, Kansas, area. The Des Moines Series in Kansas includes the lower part of the Pennsylvanian System, from an unconformity at its base to an unconformity at the base or within the Pleasanton shale (Moore, 1936, p. 51). Further defining the Des Moines series in Kansas and surrounding states, Moore (1936) states, "The lower boundary of the Des Moines series is sharply defined. North of the Kansas-Oklahoma line strata of Morrow age, which represent a part of Pennsylvanian time that is older than Des Moines, are absent. Except locally, beds of Late Mississippian (Chester) age are lacking also, and therefore the basal Des Moines rests on Middle Mississippian limestones or it overlaps the Mississippian and is found on older Paleozoic rocks of the Ozark uplift." Moore et al. (1944) designated Des Moines as the Desmoinesian Series for a major Pennsylvanian time-rock division in the midcontinent, and Moore, Frye, and Jewett (1944) recognized Desmoinesian Series in Kansas.

The name "Atokan" as a series was suggested by Spivey and Roberts (1946), based on fusiform fusulinids in rock units in central Texas that were post-Morrow in age. Because of stratigraphic problems with existing names, the authors chose the Atokan formation of Oklahoma and elevated it to series level based on the Fusulina-Wedekindellina presence of beds overlying beds of Desmoinesian age and the presence of Fusulinella in the Atokan beds.

Agreement on Pennsylvanian stratigraphic nomenclature was determined by the geological surveys of Kansas, Missouri, Nebraska, Iowa, and Oklahoma for units northeastward from northern Oklahoma (Moore, 1948). This agreement was reached in a meeting in Lawrence, Kansas, on May 5-6, 1947, that was attended by four of the five state surveys, with Oklahoma giving its concurrence later. Rock units of Desmoinesian, Missourian, and Virgilian time-rock subdivisions were recognized, with older Pennsylvanian units of Morrowan and Atokan recognized where differentiated. Later, Moore (1949, p. 32) believed Atokan rocks to be present in eastern Kansas and in the deeper basins in the midcontinent region.

Representatives from five states (Missouri, Kansas, Oklahoma, Nebraska, and Iowa) met in Nevada, Missouri (March 31-April 1, 1953) to establish the stratigraphy of platform deposits of pre-Marmaton Desmoinesian beds that includes the Cherokee Group, including the Riverton coal and the underlying beds (Searight et al., 1953). Generally following this established terminology, Howe (1956) presented detailed studies of the Cherokee Group, and he included that group and the underlying Pennsylvanian rocks in the Desmoinesian Stage. Later, Searight and Howe (1961) included the Riverton Formation (the lowermost formation in the Cherokee Group at that time) in the Atokan Stage.

Rocks of lowermost Cherokee Group were considered Desmoinesian or possibly upper Atokan in the outcrop area of southeast Kansas. Lowermost Pennsylvanian rocks in the Forest City basin in northeast Kansas are considered to be older than Pennsylvanian rocks in the outcrop area, and are believed to be Atokan (Jewett et al., 1968, p. 23).

In northwest Missouri, the McLouth Formation that was formally named for the subsurface McLouth sandstones first described by Lee (1941) from drill cuttings in western Jefferson County, Kansas, were considered to be Atokan in age (Searight and Howe, 1961). The overlying Riverton Formation is also considered to be Atokan in age in Missouri (Searight and Howe, 1961), while rocks equivalent to the Riverton Formation of Missouri are considered to be Desmoinesian age in Kansas (Jewett et al., 1968). Brady et al. (1994, sheet 1) compared these similar lithologies and associated stratigraphic units in southeast Kansas and southwest Missouri. In the stratigraphic columns of the publication, the discrepancy of ages assigned for similar units is clearly illustrated.

Stewart (1975) stated that not much is known about the paleontology in the deeper parts of the Forest City basin, but that regional relationships support placing the oldest Pennsylvanian strata in the Atokan. Nodine-Zeller and Thompson (1977) reported the presence of several conodonts in black shale in a core from Cherokee County, Kansas, which indicates an Atokan (possibly early Atokan) age. In the same report Wilson (personal communication) thought that spores from the same shale are also Atokan (or Morrowan) in age. Wilson (1976b) concluded that his study of the Atoka Formation at its type section in Oklahoma and in other areas indicates that the palynomorph assemblages are nearly identical with those in the Hartshorne Formation and are Desmoinesian in age. His conclusions, however, were based largely on spore genera, whose ranges overlap the Desmoinesian and Atokan. Rashid (1968) and Wilson and Rashid (1982) found that the spore assemblage in the Bostwick Member in southern Oklahoma, which was thought to be Atokan in age, is actually Desmoinesian. The Atokan had been cut out by erosion before deposition of the Desmoinesian (Clopine, 1991).

Ravn (1979) reported in detail on the palynology of the Blackoak Coal Member in Iowa, which is just below the Atokan-Desmoinesian boundary. Ravn (1986) also described the palynomorph composition of Morrowan to Missourian coal beds in Iowa and correlated the coals with those in the Illinois basin. The Atokan in Iowa includes the Kilbourn Formation, which contains several unnamed coal beds, and the overlying Kalo Formation containing the Blackoak Coal.

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Kansas Geological Survey
Web version Aug. 16, 2007