Visean

Visean
Scotese, Christopher R.; Vérard, Christian; Burgener, Landon; Elling, Reece P.; · CC BY 4.0 · source
Name	Visean
Start	346.7
End	330.9
Unit	Stage/Age
Timescale	Carboniferous
Chronostrat	Mississippian

Visean The Visean is an interval of the Early Carboniferous recognized in regional and global chronostratigraphy. It is defined by stratigraphic sections and biostratigraphic markers used across Europe, North America, Asia, Africa and Australia, and is central to correlations among the Mississippian, Devonian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Paleozoic, Phanerozoic and other major geologic units. It is referenced in lithostratigraphic studies of formations such as the Carboniferous Limestone, Dinantian, Toursian, Serpukhovian and by regional geologists working in basins like the Rheic Ocean, Variscan Belt, Appalachian Basin, Basin and Range Province, Sichuan Basin, Paraná Basin, Karoo Basin, Lachlan Fold Belt, Mackenzie Basin, North Sea Basin, Sahara Platform, Ebro Basin, Paris Basin, London Basin, Pennine Basin, Cantabrian Zone, Bohemian Massif, Armorican Massif, Sudetes, Urals, Kazakh Shield, Siberian Platform, Tarim Basin, Yangtze Platform, Indian Shield, Gondwana.

Definition and temporal context

The Visean stage is placed within the global timescale between the Tournaisian and Serpukhovian and is chronometrically constrained by geochronological work involving researchers from institutions like the International Commission on Stratigraphy, Geological Society of London, United States Geological Survey, British Geological Survey and laboratories at Utrecht University, University of Oxford, Université Lille, University of Edinburgh, Stanford University, University of California, Berkeley and Chinese Academy of Sciences. It is tied to ammonoid, conodont and foraminifer zonations developed by paleontologists following schemes of Alfred Wegener-era synthesis and later refinements by R. L. Hallam, A. Hall, J. W. Wells, M. L. Droser and P. A. Allison. Global correlation employs markers used in sections such as the stratotypes at Holkerian', the reference sections in Belgium, Russia, China and type localities in the United Kingdom.

Stratigraphy and lithology

Visean successions include carbonate platforms, reef complexes, turbidites and siliciclastic interbeds recorded in lithostratigraphic units like the Carboniferous Limestone Supergroup, Yoredale Group, Inferior Oolite, Millstone Grit Group, Mauch Chunk Formation, Bear Gulch Limestone, Blue Lias-equivalents and regional formations named in the Appalachians, Pennines, Alps, Carpathians, Caledonides and Variscides. Lithologies range from micritic limestones, bioclastic packstones, grainstones, dolostones, marls, cherts and black shales to siltstones and sandstones associated with deltas studied by researchers at Imperial College London, University of Glasgow, Trinity College Dublin, University of Toronto, University of Sydney and Monash University. Diagenetic fabrics, sequence stratigraphy and chemostratigraphy work ties to studies by teams at Lamont–Doherty Earth Observatory, Max Planck Institute for Chemistry, Scripps Institution of Oceanography and GEOMAR.

Paleogeography and climate

Paleogeographic reconstructions for the Visean use paleomagnetic and plate reconstructions from groups at Paleomap Project, University of Michigan, Columbia University, University of Chicago and ETH Zurich. These reconstructions place continental blocks such as Laurentia, Baltica, Avalonia, Gondwana and microcontinents like Armorica in positions that fostered shallow epicontinental seas and carbonate platforms. Climatic interpretations reference glacio-eustatic signals linked to Late Paleozoic icehouse states debated by scholars including Peter Ward, Andy Ridgwell, Richard Fortey, Michael Benton, Ian Tattersall and Mark Sephton. Models from NASA Goddard, NOAA, MPI for Meteorology and university groups simulate sea-level, monsoon and greenhouse–icehouse dynamics during the stage.

Fossils and biota

Fossil assemblages from Visean strata preserve benthic reef builders like stromatoporoids, tabulate corals, rugose corals, and calcareous algae recorded in collections at the Natural History Museum, London, Muséum national d'Histoire naturelle, Paris, Smithsonian Institution, Royal Ontario Museum, Australian Museum, Russian Academy of Sciences, Zhejiang Museum of Natural History, National Museum of Natural History (France), American Museum of Natural History and universities. Marine faunas include brachiopods such as Productida, Spiriferida, echinoderms including crinoids, bivalves, gastropods, ammonoids and conodont elements used by experts like G. K. Merrill, A. K. Ward, J. L. Serpagli, Helen Muir-Wood, James Hall and Charles Lapworth. Terrestrial records yield early lycopsids, progymnosperms, fern allies, and arthropods including arachnids and myriapods studied by teams at University of Manchester, University of Bonn, Université de Liège and University of Leeds.

Economic significance and resources

Visean carbonates and associated siliciclastics host reservoirs and source rocks exploited in hydrocarbon provinces such as the North Sea, Gulf of Mexico Basin, Caspian Sea Basin, Persian Gulf, Timor Sea, Bonaparte Basin, Golfito Basin, East China Sea Basin, Amazon Basin and Sichuan Basin. Mineralization includes Mississippi Valley-type deposits, carbonate-hosted lead–zinc occurrences, and building stone quarried as Portland and limestone used in heritage sites like Westminster Abbey, Notre-Dame de Paris and industrial aggregates mined by firms including BP, Shell, TotalEnergies, ExxonMobil, Chevron and regional mining companies. Karst aquifers derived from Visean limestones are important to water supplies for cities such as Rome, Paris, London, Madrid and Lisbon.

Research history and key studies

Historical work on the stage involves 19th-century geologists like Robert Chamberlin, Roderick Murchison, Adam Sedgwick, William Smith and later stratigraphers including Charles Lapworth and Archibald Geikie. Twentieth- and twenty-first-century contributions come from collaborative projects at International Commission on Stratigraphy, regional surveys by the British Geological Survey, United States Geological Survey, Geological Survey of Canada, Geological Survey of India, Geological Survey of China and major syntheses by authors such as A. Hallam, M. J. Benton, F. A. Bestland, P. A. Allison and R. A. Cooper. Key reference sections, biostratigraphic zonations and isotopic studies are documented in monographs published by Cambridge University Press, Elsevier, Springer, Geological Society of America and conference proceedings of the International Congress on Carboniferous Stratigraphy and Geology.

Category:Carboniferous stages