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| Cherokee Group | |
|---|---|
| Name | Cherokee Group |
| Type | Geological group |
| Period | Pennsylvanian |
| Age | Late Carboniferous |
| Primary lithology | Shale, coal, sandstone |
| Other lithology | Limestone, siltstone, claystone |
| Named for | Cherokee County |
| Region | Midcontinent United States |
| Country | United States |
Cherokee Group
The Cherokee Group is a Late Carboniferous (Pennsylvanian) stratigraphic unit of the Midcontinent of the United States, notable for its coal-bearing successions, cyclothemic sequences, and significance to regional resource development. It has been studied extensively in relation to Pennsylvanian paleoenvironments, cyclothems, and economic geology that influenced mining in states including Kansas, Oklahoma, Missouri, and Iowa. Researchers from institutions such as the United States Geological Survey, Kansas Geological Survey, and various universities have produced stratigraphic correlations and paleontological inventories across its outcrops and subsurface occurrences.
The group comprises a succession of interbedded shales, sandstones, claystones, coal seams, and subordinate limestones deposited during the Pennsylvanian epoch, reflecting repeated transgressive–regressive cycles associated with the Late Carboniferous glacioeustatic changes recorded in the Appalachian Basin and the Midcontinent Basin. Classic studies by geologists affiliated with the Kansas Geological Survey and the University of Kansas emphasized its importance for correlating coal beds and cyclothems across the Midwestern interior. It is often discussed in the context of regional stratigraphic frameworks developed by the United States Geological Survey and state surveys.
Stratigraphically, the Cherokee Group overlies Mississippian and older Pennsylvanian units such as the Marmaton Group in parts of the Midcontinent and is overlain by younger Pennsylvanian strata including the Marmatonian to Desmoinesian equivalents, depending on locality. Formal subdivisions vary by state and historical usage; lithostratigraphic members and formations recognized by the Kansas Geological Survey, Oklahoma Geological Survey, and Missouri Geological Survey include multiple named coal seams and marker beds tied to biostratigraphic and palynological zonations developed at institutions like the University of Missouri and the Iowa Geological Survey. Correlation frameworks often reference chronostratigraphic charts maintained by the International Commission on Stratigraphy.
Lithologically, the group features green to gray marine and nonmarine shales, channelized and sheet sandstones, underclays, and multiple coal seams formed from peat accumulation in coastal plain and deltaic settings. Detailed sedimentological analyses by researchers at the University of Kansas, Oklahoma State University, and Iowa State University documented fluvial point-bar, crevasse splay, tidal flat, and estuarine facies within sandstone bodies correlated to regional sequence stratigraphy models promulgated in literature by the Society for Sedimentary Geology and the Paleoenvironmental Research Center. Mineralogic studies often cite clay assemblages analyzed through collaboration with laboratories at the Smithsonian Institution and state mineral agencies.
Fossil assemblages preserved in the Cherokee Group include plant macrofossils (lycopsids, sphenopsids, pteridosperms), marine invertebrates in restricted limestone beds (brachiopods, bivalves), and palynological assemblages used for biostratigraphic correlation. Collections and identifications have been made by paleobotanists associated with the Field Museum, the University of Illinois, and the Paleontological Research Institution, with palynology contributions from laboratories at the United States Geological Survey and the University of Nebraska. Fossil evidence supports interpretations linking Cherokee floras to Late Carboniferous wetland systems similar to those described from the Appalachian Basin and European coal basins.
The depositional history records cyclic coastal-plain, deltaic, and marginal-marine environments driven by Late Carboniferous glacioeustasy tied to ice fluctuations in Gondwana and regional subsidence of the Midcontinent cratonic basin. Basin-evolution models incorporating data from the Cherokee Group have been integrated into broader syntheses by researchers at the U.S. Army Corps of Engineers, the American Association of Petroleum Geologists, and university research groups to explain trends in accommodation space, sediment supply from Appalachian-derived uplift, and peat preservation in foreland and intracratonic settings.
The Cherokee Group is economically important for coal resources that supported 19th- and 20th-century mining in Kansas, Oklahoma, and Missouri, and for local sandstone reservoirs and shale source-rock considerations examined by the Energy Information Administration and state energy offices. Coal seams within the group were targeted by companies operating under state mining regulations administered by agencies such as the Oklahoma Corporation Commission and the Kansas Department of Health and Environment. Geologists have also evaluated potential for hydrocarbons, aggregate, and clay resources through cooperative studies with the United States Geological Survey and regional commodity agencies.
The unit was named in the late 19th and early 20th centuries for exposures in Cherokee County, Kansas and nearby areas, with early descriptions contributed by geologists from the Geological Survey of Kansas and workers publishing in outlets like the Bulletin of the American Association of Petroleum Geologists. Subsequent formalization of nomenclature and regional revisions were undertaken by the United States Geological Survey and state geological surveys, with stratigraphic schemes updated following conventions promoted by the North American Commission on Stratigraphic Nomenclature.
The Cherokee Group crops out and occurs in the subsurface across the Midcontinent, with notable exposures and mine localities in southeastern Kansas, northeastern Oklahoma, southwestern Missouri, and parts of Iowa and Nebraska. Key type and reference sections have been measured near towns and localities mapped by state surveys and archived in collections at the Kansas Geological Survey and the Oklahoma Geological Survey, providing field sites for ongoing research by regional universities and federal agencies.
Category:Carboniferous geology of the United States Category:Pennsylvanian