Clore Formation

Clore Formation
Name	Clore Formation
Type	Geological formation
Period	Pennsylvanian
Region	Illinois Basin
Country	United States
Unitof	McLeansboro Group
Underlies	Degola Limestone
Overlies	Patoka Formation

Clore Formation The Clore Formation is a Pennsylvanian-age stratigraphic unit within the Illinois Basin region of the United States that crops out in parts of Illinois, Indiana, and Kentucky. It is recognized in stratigraphic columns used by the United States Geological Survey and by state geological surveys in Illinois and Indiana, and it contributes to interpretations of Carboniferous paleoenvironments reconstructed by researchers at institutions such as the University of Illinois and Indiana University. The formation is important for studies tied to coal-bearing sequences, basin subsidence, and paleofaunal assemblages documented in North American paleontology literature.

Description and Geologic Setting

The Clore Formation occurs within the Illinois Basin, a structural basin bounded by the Appalachian Basin, Ozark Dome, and Michigan Basin, and it is part of the broader Midcontinent cyclothemic succession recognized by the United States Geological Survey and the American Association of Petroleum Geologists. The unit sits within the McLeansboro Group stratigraphy that has been correlated with equivalent units in the Appalachian Basin, Illinois Basin, and the Western Interior Seaway reconstructions used by researchers at the Smithsonian Institution and the Field Museum. Basin analysis involving the Clore Formation frequently references tectonic influences from the Ouachita orogeny and boundary relationships with the Cincinnati Arch, Findlay Arch, and the Kankakee Arch documented by the Indiana Geological and Water Survey.

Stratigraphy and Lithology

Stratigraphically, the Clore Formation overlies the Patoka Formation and is overlain by units such as the Degola Limestone or equivalents depending on local nomenclature used by the Illinois State Geological Survey and the Kentucky Geological Survey. Lithologic descriptions by state surveys and academic studies at Southern Illinois University indicate interbedded shales, siltstones, sandstones, and thin coal seams, with local carbonate lenses similar to sequences reported in cyclothems studied by the Geological Society of America and the American Museum of Natural History. Core logs and outcrop descriptions correlate Clore facies with logs archived by the United States Department of the Interior and petroleum industry reports submitted to the Illinois State Geological Survey and the Indiana Geological and Water Survey.

Age and Paleontology

The Clore Formation is assigned to the late Pennsylvanian subperiod, correlating with global chronostratigraphic frameworks maintained by the International Commission on Stratigraphy and used in regional correlation with Appalachian Pennsylvanian units described in monographs from the Paleontological Society. Fossil assemblages reported from Clore exposures include plant megafossils and palynological taxa comparable to those cataloged at the Field Museum and the Smithsonian National Museum of Natural History, as well as marine invertebrates and trace fossils that permit correlation with faunal lists maintained by the Paleobiology Database and publications in journals such as the Journal of Paleontology and the Proceedings of the United States National Museum. Biostratigraphic work referencing fusulinids, brachiopods, and plant macrofossils has been integrated into regional correlation charts produced by the United States Geological Survey and state geological surveys.

Depositional Environment and Paleoecology

Interpretations of the Clore Formation's depositional environments derive from facies analysis in studies by the Geological Society of America and university research groups at the University of Illinois and Indiana University, which infer deltaic to paralic, coastal-plain settings with episodic marine incursions linked to Late Pennsylvanian glacioeustatic cycles documented in literature from the American Geophysical Union and the International Union of Geological Sciences. Paleoecological reconstructions emphasize coal-forming peat mires, mangrove-like swamp floras analogous to collections at the Royal Ontario Museum and the Field Museum, and marginal marine communities that show affinities to assemblages described from the Appalachian Basin and the Midcontinent by the Paleontological Research Institution. Sedimentological comparisons often reference modern analogs in the Mississippi Delta and Pleistocene transgressive sequences studied by the United States Army Corps of Engineers.

Economic Resources and Uses

The Clore Formation hosts thin coal seams and sandy intervals that have been evaluated by the Illinois State Geological Survey and the Indiana Geological and Water Survey for potential resource exploitation, with historic small-scale coal production and modern assessments by the United States Energy Information Administration and the Department of Energy. Sandstone and aggregate resources from Clore-related strata have been used locally for construction materials documented in state mineral commodity reports and municipal engineering records, and assessments of groundwater within porous intervals involve hydrogeologic frameworks employed by the United States Geological Survey and state water resources agencies.

History of Study and Naming

The Clore Formation was defined in regional stratigraphic work conducted by state geological surveys and early 20th-century geologists who correlated Pennsylvanian cyclothems across Illinois, Indiana, and Kentucky in reports submitted to the United States Geological Survey and presented at meetings of the Geological Society of America. Subsequent revisions and formal usage appear in stratigraphic compilations by the Illinois State Geological Survey, the Indiana Geological and Water Survey, and syntheses published by the United States Geological Survey, with continued refinements in lithostratigraphic and biostratigraphic correlations appearing in academic theses at Southern Illinois University, Indiana University, and the University of Kentucky.

Category:Carboniferous geology of North America