Autunian
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| Autunian | |
|---|---|
| Name | Autunian |
| Color | #ffd070 |
| Time start | 298.9 |
| Time end | 295.0 |
| Time unit | Ma |
| Preceded by | Gzhelian |
| Followed by | Sakmarian |
Autunian The Autunian is a regional Early Permian interval recognized in European and adjacent stratigraphic schemes, notable for its floral turnovers and vertebrate assemblages. It is characterized by distinctive lithologies, faunal turnovers, and correlations with international stages, and has been influential in debates on Permian regionalization and basin evolution.
Definition and Etymology
The name derives from the city of Autun in Burgundy, where classic exposures and type sections were described in the 19th century during work by investigators connected to institutions such as the Muséum National d'Histoire Naturelle and universities like the University of Paris. Early papers by geologists associated with the Comité des Travaux Historiques et Scientifiques and the Société Géologique de France established the term while comparing sequences with successions in Holland, Belgium, and the United Kingdom. Subsequent formalization involved stratigraphers from organizations including the International Commission on Stratigraphy and regional surveys such as the British Geological Survey and the Service géologique national (France).
Geologic Age and Stratigraphy
The Autunian occupies the earliest Permian, broadly overlapping with parts of the Asselian and Sakmarian global stages, and is constrained by biostratigraphic ties to fusulinids, conodonts, and palynofloras used by workers from the Russian Academy of Sciences, the Geological Survey of Canada, and the United States Geological Survey. Key stratotypes in the Massif Central and the Rhenish Massif display successions from the upper Carboniferous (Gzhelian) through the Autunian into overlying units correlated with the Kungurian in some classifications. Multidisciplinary correlation efforts by researchers affiliated with institutions such as ETH Zurich, the University of Göttingen, and the Naturhistorisches Museum Wien have integrated magnetostratigraphy, chemostratigraphy, and radiometric dates to refine Autunian boundaries.
Paleontology and Fossil Record
Fossil assemblages from Autunian strata document a transition in terrestrial biota, including floras dominated by Glossopteris-grade elements, pteridosperms related to Medullosales, and early occurrences of conifers akin to taxa studied at the Royal Botanic Gardens, Kew and the Natural History Museum, London. Vertebrate records include temnospondyls comparable to those described by workers at the Institute of Paleontology, Moscow and amniotes that have been compared to early synapsids known from collections at the Smithsonian Institution and the Natural History Museum of Los Angeles County. Invertebrate faunas from marine-influenced Autunian horizons show continuities with Goniatites and bivalves analyzed in the Paleontological Museum, University of Uppsala and molluscan assemblages correlated with sites curated by the Museo Nacional de Ciencias Naturales (Madrid). Palynological investigations by teams from the Australian National University and the University of Sao Paulo have refined biostratigraphic zonations using spores and pollen shared with Permian successions in Kazakhstan and the Siberian Platform.
Sedimentary Environments and Lithology
Autunian exposures reveal a range of lithofacies from fluvial sandstones and conglomerates documented in the Massif Central to lacustrine shales and coal-bearing seams comparable to deposits in Westphalia and the East European Craton. Key lithologies include red-bed sandstones studied by the Geologische Bundesanstalt and carbonaceous mudstones sampled by researchers at the University of Lyon; evaporitic horizons parallel sequences in the Hercynian Basin and salt-bearing units investigated by the Norwegian Geological Survey. Sedimentological work by teams from the University of Manchester, the University of Barcelona, and the Max Planck Institute for Chemistry has emphasized alluvial fan, playa, and floodplain settings, with paleosol development comparable to Permian paleosols described from the Zechstein and Rotliegend basins.
Correlation and Regional Extent
The Autunian is best developed in western and central Europe, with lateral equivalents recognized in basins of France, Germany, Belgium, Luxembourg, and the United Kingdom, and correlative successions inferred in the Iberian Massif and parts of the Bohemian Massif. International correlation efforts link Autunian intervals to the Asselian of the International Commission on Stratigraphy timescale and to coeval successions in North America (e.g., Permian sequences curated by the American Museum of Natural History), China (collections at the Nanjing Institute of Geology and Palaeontology), and Russia (research from the Paleontological Institute, Russian Academy of Sciences). Regional mapping by the Institut Géologique de Lorraine and cross-border projects with the European Geological Surveys has clarified the Autunian's basin-to-basin variability and its role in reconstructing Permian paleogeography alongside reconstructions by groups at the University of Texas at Austin and the Paleomap Project.
History of Research and Naming
19th-century work by geologists connected to the École des Mines de Paris and the École Normale Supérieure established Autunian lithostratotypes, with systematic descriptions published in journals such as the Bulletin de la Société Géologique de France and proceedings of the Académie des Sciences. Later 20th-century revisions involved scholars affiliated with the University of Freiburg, the University of Strasbourg, and the Centre National de la Recherche Scientifique who compared Autunian successions to the Permian Basin model advanced by North American and Soviet geologists. Contemporary syntheses and nomenclatural decisions have been debated within forums of the International Union of Geological Sciences and formalized through working groups of the International Commission on Stratigraphy and national stratigraphic committees, ensuring integration with global chronostratigraphic charts maintained by institutions such as the United States Geological Survey and the Geological Survey of Canada.