Pennsylvanian (Carboniferous)
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| Pennsylvanian (Carboniferous) | |
|---|---|
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| Name | Pennsylvanian |
| Color | #8FBF8F |
| Time start | 323.2 |
| Time end | 298.9 |
| Unit of | Carboniferous |
| Preceding | Mississippian |
| Following | Permian |
Pennsylvanian (Carboniferous) is the younger subperiod of the Carboniferous and marks a major interval of Late Paleozoic time characterized by extensive coal-bearing strata, vast tropical wetlands, and significant tectono-sedimentary events. It spans key chronostratigraphic stages and correlates with regional series used in North America, Europe, and Asia while intersecting the scientific histories of figures and institutions that developed modern stratigraphy.
Definition and Temporal Framework
The Pennsylvanian subperiod is formally bounded by chronostratigraphic definitions established through work associated with the International Commission on Stratigraphy, with numeric ages tied to radiometric calibrations from studies at institutions such as the United States Geological Survey, Geological Society of America, and laboratories collaborating with the Royal Society. Correlations link North American stages like the Bashkirian Stage, Moscovian Stage, Kasimovian Stage, and Gzhelian Stage to global chronostratigraphic units used in publications by the British Geological Survey and the Geological Survey of Canada. Debates over numerical boundaries have involved research groups at Massachusetts Institute of Technology, University of Cambridge, Stanford University, and the University of Oxford using biostratigraphy, magnetostratigraphy, and isotopic dating.
Stratigraphy and Regional Subdivisions
Regional stratigraphic schemes for the Pennsylvanian were developed within national frameworks such as the United States Geological Survey's Appalachian and Midcontinent stratigraphies, the British Geological Survey's European coal measures, the Geological Survey of India's Gondwanan sequences, and the Chinese Academy of Sciences's Yangtze and North China basins. North American chronostratigraphy uses formations like the Pottsville Formation, Allegheny Formation, and Black Warrior Basin units; European schemes reference the Westphalian Stage and Stephanian Stage. Correlations among the Ural Mountains, Appalachian Mountains, Hercynian orogeny, and Ancestral Rocky Mountains relied on biostratigraphic markers such as fusulinids, conodonts, and ammonoids studied by paleontologists at the Natural History Museum, London and the Smithsonian Institution.
Paleoenvironments and Climate
Pennsylvanian paleoenvironments encompassed equatorial peat-forming mires, deltaic complexes, epicontinental seas, and seasonally wet tropical lowlands interpreted from sedimentary facies documented in the Midcontinent Rift System, Paraná Basin, Donets Basin, and South China Block. Climate reconstructions drawing on isotope work led by teams at the California Institute of Technology, University of California, Berkeley, and the Max Planck Institute for Chemistry indicate warm greenhouse intervals punctuated by glacioeustatic fluctuations linked to the Antarctic glaciation of Gondwana and icehouse pulses recorded in the Karoo Basin and Permo-Carboniferous glaciation studies. Atmospheric models developed with input from researchers at NASA and NOAA explore links between high oxygen levels, coal burial rates, and wildfire incidence recognized by investigators at the University of Chicago and the University of Edinburgh.
Flora and Fauna
Vegetation of Pennsylvanian coal swamps included arborescent lycopsids such as Lepidodendron, sphenopsids like Calamites, progymnosperms, and early seed ferns documented in collections at the Field Museum and the American Museum of Natural History. Terrestrial arthropods achieved giant sizes—exemplified by genera studied by teams at the Natural History Museum, London and the University of Kansas—including large myriapods and insects whose physiology has been modeled at Imperial College London. Vertebrate faunas comprised diverse early tetrapods and amphibians from localities investigated by researchers at the University of Toronto and the University of Ghent, while marine assemblages of brachiopods, crinoids, bryozoans, and foraminifera were cataloged by the Smithsonian Institution and the Muséum national d'Histoire naturelle.
Tectonics and Sedimentation
Major tectonic events influencing Pennsylvanian sedimentation include the culmination of the Alleghanian orogeny, collision events between Laurussia and Gondwana during the assembly of Pangaea, and strike-slip processes recorded in the Ouachita orogen and Variscan Belt. Foreland basins such as the Appalachian Basin, intracratonic basins like the Midcontinent Basin, and forearc systems recorded sediment dispersal patterns analyzed through seismic data contributed by companies and agencies including Schlumberger, BP, and national geological surveys. Sedimentological research at the University of Texas at Austin and the University of Manchester has linked cyclic deposition, cyclothems, and sequence stratigraphy to glacioeustatic forcing and tectonic subsidence.
Economic Importance and Resources
The Pennsylvanian is economically critical for coal resources exploited historically by industries and institutions such as the Pennsylvania Railroad, U.S. Steel, and modern energy companies including ExxonMobil and Royal Dutch Shell in basins like the Illinois Basin and Donets Basin. Hydrocarbon reservoirs in Pennsylvanian strata have been developed in the Anadarko Basin, Permian Basin (basal Pennsylvanian units), and parts of the North Sea; exploration and production activities involve corporations such as Chevron and TotalEnergies and regulatory oversight by agencies like the U.S. Department of Energy. Coal petrography, mining legislation, and labor history intersect with organizations including the United Mine Workers of America and research institutions like the Colorado School of Mines.
History of Study and Nomenclature
The term and concept of the Pennsylvanian evolved through 19th-century stratigraphers and geologists working in the coalfields of Pennsylvania and beyond, with contributions from figures associated with the Geological Society of London, Benjamin Silliman-era American geology, and European contemporaries who refined chronostratigraphic nomenclature. Debates over regional versus global stages, championed by researchers at universities such as Yale University, University of Pennsylvania, and University of Bonn, led to the current framework codified by the International Commission on Stratigraphy and reflected in stratigraphic charts used by the United States Geological Survey and the International Union of Geological Sciences.