This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Mansfield Formation | |
|---|---|
| Name | Mansfield Formation |
| Type | Formation |
| Period | Permian |
| Region | Indiana, Kentucky, Ohio |
| Country | United States |
| Unitof | Raccoon Creek Group |
| Subunits | Mansfield Coal Member |
| Underlies | Trafalgar Formation |
| Overlies | New Harmony Formation |
Mansfield Formation The Mansfield Formation is a Permian-age stratigraphic unit of the Midwestern United States notable for its coal-bearing sequences and fossil assemblages. Exposed primarily in Indiana, with extensions into Kentucky and Ohio, it has been studied in association with regional stratigraphic frameworks such as the Raccoon Creek Group and correlated to broader cyclothems documented across the Illinois Basin and the Appalachian Basin. The unit has significance for regional paleoecology, economic coal resources, and basin-scale sedimentary history investigated by institutions like the United States Geological Survey and universities including Indiana University.
The Mansfield Formation lies within the Late Pennsylvanian subsystem of the Carboniferous and is mapped across the north-central portion of the Illinois Basin and adjacent parts of the Michigan Basin margins. Stratigraphically it is commonly placed above the New Harmony Formation and below the Trafalgar Formation, and is part of the upper stratigraphy of the Raccoon Creek Group. Regional stratigraphers from agencies including the Indiana Geological and Water Survey and the Kentucky Geological Survey have differentiated its members using marker beds correlated to widespread cyclothems recognized in studies by the United States National Museum and published in bulletins by the American Association of Petroleum Geologists. Lateral facies changes documented near the Ohio River and in outcrops at Mansfield, Indiana (namesake region) demonstrate typical Pennsylvanian variability seen in classic studies by researchers affiliated with Ohio State University and Purdue University.
The Mansfield Formation comprises cyclic sequences of sandstones, siltstones, shales, and coal seams, with local carbonate and seat-earth horizons. Petrographic and sedimentological analyses by investigators at the University of Illinois Urbana–Champaign and the Indiana Geological Survey describe fluvial to deltaic channel sandstones, overbank mudstones, and peat-derived coalbeds such as the Mansfield Coal Member. Grain-size studies align with regional sandstone units correlated with fluvial systems evaluated in reports by the Society for Sedimentary Geology and paleoflow reconstructions tied to paleogeographic syntheses by the Paleontological Society. Authigenic mineral assemblages and clay mineralogy have been compared with Permian successions documented by the Geological Society of America.
Fossil content includes plant megafossils, palynomorph assemblages, and occasional invertebrate remains that provide biostratigraphic and paleoecological data. Macrofossils such as lycopsids, sphenopsids, and pteridosperms are reported from coal-bearing horizons, with collections cataloged by institutions like the Smithsonian Institution and the Field Museum of Natural History. Palynological studies undertaken by researchers at West Virginia University and Indiana University have yielded spores and pollen enabling correlation to regional Pennsylvanian palynozones used by the International Commission on Stratigraphy. Invertebrate fossils including freshwater bivalves and trace fossils tie the unit to faunal lists compiled by curators at the American Museum of Natural History.
Biostratigraphic and radiometric calibration place the Mansfield Formation in the Late Pennsylvanian (Late Carboniferous), with correlations drawn to contemporaneous cyclothems across the Illinois Basin and into the Appalachian Basin. Correlation frameworks use palynology, megafloral assemblages, and marker beds compared with type sections documented by the United States Geological Survey and synthesised in regional correlation charts published by the Geological Society of America. Its age equivalence with portions of the Desmoinesian to Missourian stages has been discussed in stratigraphic reviews by researchers at Purdue University and the Ohio Geological Survey.
Sedimentological and paleobotanical evidence indicates deposition in coastal plain to fluvio-deltaic settings influenced by repeated transgressive-regressive cycles. Peat accumulation in low-lying mire systems, progradation of deltaic lobes, and channel migration are consistent with depositional models advocated in basin studies produced by the United States Geological Survey and academic analyses from Indiana University Bloomington. Climatic and sea-level controls referenced in regional work by the Paleontological Society and the International Union of Geological Sciences support cyclic coal formation and interbedded siliciclastic deposition typical of late Carboniferous tropical wetland systems.
The Mansfield Formation hosts economically significant coal seams, historically mined by operators and documented in production statistics from the Indiana Department of Natural Resources and the Kentucky Energy and Environment Cabinet. Coal from the Mansfield Coal Member has been utilized for steam generation and metallurgical processes, with analyses of calorific value and ash content presented in technical reports from the United States Department of Energy and energy research centers at Purdue University. Sandstone units have been evaluated as potential aquifers by hydrogeologists at the Indiana Geological Survey and municipal water authorities in Terre Haute and surrounding counties.
The name derives from exposures near Mansfield, Indiana, and early stratigraphic descriptions appeared in 19th- and early 20th-century surveys conducted by the Indiana State Geological Survey and contributors to the United States Geological Survey. Subsequent detailed mapping, palynological studies, and economic assessments were advanced by academic institutions including Purdue University, Indiana University, and Ohio State University, as well as state geological surveys. Key stratigraphic syntheses and coal resource appraisals were published in bulletins by the United States Geological Survey and presented at meetings of the Geological Society of America.
Category:Geologic formations of Indiana