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| Permian-Triassic | |
|---|---|
| Name | Permian–Triassic |
| Start | 298.9 Ma |
| End | 201.3 Ma |
| Era | Phanerozoic |
| Period1 | Permian |
| Period2 | Triassic |
| Caption | Stratigraphic boundary near a continental section |
Permian-Triassic.
The term denotes the boundary interval between the Permian and Triassic periods, encompassing the latest Paleozoic and earliest Mesozoic epochs, and is recognized in global stratigraphy by biostratigraphic, chemostratigraphic, and lithostratigraphic markers developed since work by Charles Lapworth, Adam Sedgwick, and Roderick Murchison. The interval is notable for the largest known Phanerozoic extinction event, intensive magmatism connected to the Siberian Traps, and prolonged biotic recovery studied in field sections from Meishan, Ziyun County, Karoo Basin, and Dolomites.
The temporal framework is based on Global Boundary Stratotype Section and Point criteria established under the International Commission on Stratigraphy, using radiometric ages from U–Pb dating, magnetostratigraphy refined by teams at California Institute of Technology and Oxford University, and chemostratigraphic ties to excursions in carbon isotopes documented by researchers from Smithsonian Institution, University of California, Berkeley, and ETH Zurich. The boundary correlates with biotic markers such as the last occurrences of certain fusulinids, conodonts like Hindeodus parvus recognized by workers at Yale University, and palynological shifts catalogued in datasets from British Geological Survey and Geological Survey of India.
Lithostratigraphic subdivisions are mapped as formations, members, and beds in regional stratigraphy reported by the United States Geological Survey, Geological Survey of Canada, and Geologische Bundesanstalt, including the Karoo Supergroup sequences, the Zechstein evaporites, and the Newark Supergroup rift-fill basins tied to breakup phases of Pangaea. Key units such as the Beaufort Group, Chinle Formation, and Saptarshi Formation provide depositional context for fluvial, deltaic, and shallow marine environments interpreted by teams from University of Melbourne, Peking University, and Monash University.
Paleoclimatic reconstructions use proxies from oxygen isotope records measured at Max Planck Institute for Chemistry, pollen and spore assemblages described by Royal Botanic Gardens, Kew, and sedimentological facies analyses employed by University of Cambridge and University of Tokyo, revealing shifts from late glacio-eustasy influences recorded in Permian deposits to greenhouse conditions linked to carbon-cycle perturbations evaluated by International Ocean Discovery Program coring. Sea-level changes interpreted through sequence stratigraphy frameworks promoted by W. R. Phillips and Peter Vail align with palaeogeographic maps produced by PALEOMAP Project contributors and with climatic model outputs from NOAA and NASA Goddard Institute for Space Studies.
Biotic turnover is documented across marine and terrestrial realms via fossil records curated at institutions like the Natural History Museum, London, American Museum of Natural History, and Paleontological Research Institution, including disappearance of many brachiopod taxa, collapse of reef ecosystems dominated by tabulate corals and rugose corals, and loss of diverse trilobite lineages contrary to the prior resilience noted in Cambrian assemblages. Studies by paleontologists from Chinese Academy of Sciences, University of Vienna, and Cornell University trace patterns in ammonoid and conodont turnovers, while vertebrate extinction pulses in the Karoo Basin and Lystrosaurus faunal dominance are central to debates advanced at Smithsonian Institution symposia and reported in journals edited by scholars at Harvard University.
Early Triassic recovery dynamics are reconstructed from fossil assemblages in localities studied by teams from University of California, Los Angeles, University of Zurich, and University of Bern, showing opportunistic proliferation of disaster taxa such as certain bivalves and microbialites comparable to analogues discussed in literature from University of Texas at Austin and University of Göttingen. Ecosystem resilience and trophic restructuring analyses combine trace fossil data collected by Geological Survey of Japan and isotopic studies led by ETH Zurich and Imperial College London, documenting delayed recovery intervals echoed in vertebrate faunas of Madagascar and Antarctica sections.
Tectonic reconstructions by geodynamicists at Massachusetts Institute of Technology and University of California, Santa Barbara link Pangaea assembly and rifting to magmatic events such as the Siberian Traps flood basalts investigated by teams from Russian Academy of Sciences and University of Oslo, while alternative hypotheses involving methane release from clathrates and ocean anoxia have been modeled by researchers at Lamont–Doherty Earth Observatory, Woods Hole Oceanographic Institution, and University of Bremen. Proposed kill mechanisms debated at conferences hosted by Geological Society of America and European Geosciences Union include greenhouse warming, acidification, euxinia, and bolide impact scenarios tested against geochemical anomalies recorded in cores curated by International Continental Scientific Drilling Program.
Economic geology during the interval concerns hydrocarbon source rocks and evaporite-hosted mineral deposits examined by ExxonMobil geoscience groups, state surveys such as Petroleum Authority of Thailand, and consultants from Schlumberger, with stratigraphic correlation workflows using sequence stratigraphy, biostratigraphy, and chemostratigraphy standardized by committees within the International Union of Geological Sciences and implemented in basin studies from the North Sea, Gulf of Mexico, and Tarim Basin. Modern correlation integrates high-precision geochronology from Geochronology Center, University of Arizona with magnetostratigraphy datasets maintained by Pangea Data Publisher and open repositories hosted by PANGAEA.
Category:Geologic time scales