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| Olenekian | |
|---|---|
| Name | Olenekian |
| Color | #ff9999 |
| Time start | 251.2 |
| Time end | 247.2 |
| Time uncertainty | 0.3 |
| Caption | Marine strata from the Early Triassic |
| Timeline | Triassic |
| Usage | Global (ICS) |
| Timescales used | International Commission on Stratigraphy |
Olenekian The Olenekian is an Early Triassic stage notable for recovery after the Permian–Triassic crisis and for distinctive marine and terrestrial assemblages. It is constrained by global stratigraphic markers and is recognized in numerous regional stratigraphic schemes, with important sections in Siberia, China, Europe, and North America. Key studies and standards established by institutions and researchers have defined its boundaries and correlations.
The stage definition rests on type sections such as the succession at the Olenyok River region and formal ratification by bodies like the International Commission on Stratigraphy and the International Union of Geological Sciences. Boundary markers were selected using conodont biozones tied to work by paleontologists from institutions including the Geological Survey of Canada, Russian Academy of Sciences, and teams associated with the Chinese Academy of Sciences. Stratigraphically, the Olenekian follows stages defined in the Permian–Triassic literature and lies above units correlated with the Spathian and below those correlated with the Anisian. Key stratigraphic guides and chronostratigraphic charts published by the International Chronostratigraphic Chart working group integrate data from researchers at the Smithsonian Institution, Natural History Museum, London, and the Australian National University.
Age determination integrates radiometric work from volcanic ash beds analyzed by groups at the University of California, Berkeley, ETH Zurich, and the Geological Survey of Japan, coupled with biostratigraphic correlations using conodonts and ammonoids described by teams at the University of Oxford, University of Tokyo, and University of Milan. Geochronology papers in journals featuring authors from Massachusetts Institute of Technology and University of Chicago refined the Olenekian span using U-Pb zircon dates and astrochronology, with calibration against the Geologic Time Scale compilations by the International Geological Congress. Chronostratigraphic frameworks developed by researchers at the University of Oslo and Leiden University help correlate the Olenekian across the Panthalassa and Tethys Ocean realms.
Olenekian successions display lithologies ranging from siliciclastic shale and siltstone to carbonate ramp deposits documented in field studies by teams from the University of California, Los Angeles, Peking University, and University of Vienna. Depositional settings include shallow marine platforms, epicontinental seas, and restricted basins analyzed by sedimentologists at the University of British Columbia, University of Queensland, and Stockholm University. Evaporitic and anoxic facies recognized in cores studied by the Bureau of Economic Geology and the Russian Academy of Sciences indicate episodes of restricted circulation similar to analogues discussed by researchers at the Max Planck Institute for Marine Microbiology. Fluvial and deltaic sequences mapped by geologists from the University of Pretoria, University of São Paulo, and the University of Copenhagen record terrestrial inputs and climatic influence.
Marine faunas include recovery faunas of ammonoids, bivalves, and conodonts described by paleontologists at the Natural History Museum, London, Chinese Academy of Sciences, and Russian Academy of Sciences. Ichthyofauna and marine reptiles from Olenekian horizons have been studied by teams at the Field Museum, American Museum of Natural History, and University of Bonn. Terrestrial vertebrate records, including early archosauriforms and temnospondyls, were reported by researchers at the Royal Ontario Museum, University of Geneva, and Yale Peabody Museum. Microfossil and palynological assemblages examined by scientists at the University of Leeds and University of Kansas provide insights into floral recovery, while work by the Smithsonian Institution and Natural History Museum of Los Angeles County documents invertebrate and trace fossil records. Comparative taxonomy and revisions by authors affiliated with the University of Zurich and University of Milan have increased understanding of post-extinction diversification.
Paleoclimate reconstructions draw on isotope studies and climate modeling by groups at the Lamont–Doherty Earth Observatory, National Oceanography Centre, and Potsdam Institute for Climate Impact Research. Data from stable carbon and oxygen isotope work conducted at the Scripps Institution of Oceanography and University of Cambridge inform interpretations of ocean warming, euxinia, and carbon cycle perturbations. Evidence for aridification and intensified weathering has been synthesized by researchers at the Geological Survey of India and Universidade de São Paulo, while mercury anomalies linked to volcanism were documented by teams at the Geological Survey of Canada and University of Tokyo. Paleobotanical studies conducted by the Royal Botanic Gardens, Kew and Missouri Botanical Garden inform reconstructions of vegetation shifts and ecosystem stress.
Regional subdivisions and correlations involve schemes developed in the Siberian Platform, Jianghan Basin, Southern Alps, Karoo Basin, Newark Basin, and Lop Nur region. Correlation efforts feature work by stratigraphers at the University of Minnesota, Chinese University of Hong Kong, and Universidad Nacional Autónoma de México. Integrative syntheses published by groups at the University of Texas at Austin, University of Bremen, and British Geological Survey reconcile biostratigraphic, chemostratigraphic, and magnetostratigraphic datasets for global correlation, with comparative sections in the Tethyan Realm, Panthalassa, and peripheral basins of the Paleo-Tethys.
The stage marks a critical interval for post-extinction recovery studied by multidisciplinary teams from the Max Planck Institute for Evolutionary Anthropology, University College London, and the California Institute of Technology. Its record documents evolutionary radiations and ecological reorganizations examined by researchers affiliated with the Smithsonian Tropical Research Institute, Australian Museum, and University of Edinburgh. The Olenekian also provides a case study for links between large igneous province activity investigated by the Geological Survey of Norway and mass extinction research pursued at the University of Leicester and Imperial College London. Its sediments and fossils remain key for testing hypotheses about biotic resilience, climate feedbacks, and basin-scale environmental change evaluated in collaborations involving the European Research Council, National Science Foundation, and national geological surveys worldwide.
Category:Triassic stages