Carnian
Generated by GPT-5-miniExpansion Funnel Raw 65 → Dedup 0 → NER 0 → Enqueued 0
| Carnian | |
|---|---|
 Kaapitone at English Wikipedia · Public domain · source | |
| Name | Carnian |
| Color | #F7D9A6 |
| Time start | 237.0 |
| Time end | 227.0 |
| Unit | Age |
| Period | Triassic |
| Preceded by | Ladinian |
| Followed by | Norian |
Carnian The Carnian is an age of the Triassic Period recognized in global chronostratigraphy. It marks a distinct interval bounded by stratigraphic datums tied to ammonoid and conodont biostratigraphy and is notable for major biotic turnover, climatic perturbation, and sedimentary changes documented across marine and terrestrial basins worldwide.
Definition and Temporal Boundaries
The formal base of the Carnian is defined by a Global Boundary Stratotype Section and Point (GSSP) correlated to the first appearance datum (FAD) of ammonoid taxa and conodont occurrences used in chronostratigraphy and tied to radiometric calibration from U–Pb zircon ages from volcanic ash beds near proposed sections. Key stages and boundaries reference work by the International Commission on Stratigraphy and regional schemes such as the Newark Supergroup chronologies and Mediterranean stratotypes. The top of the Carnian, base of the Norian, is constrained by ammonoid zonation correlated with magnetostratigraphy from sections in the Southern Alps and stratotypes documented in classic studies by researchers from institutions including the Natural History Museum, London and the University of Padua.
Stratigraphy and Subdivisions
Carnian stratigraphy employs ammonoid, conodont, and radiolarian biostratigraphy within formal substages and biozones recognized in the Tethys realm and provincial sequences such as the Newark Basin, Germanic Basin, and Chilean Andes. Subdivisions include the Julian and Tuvalian substages in the Mediterranean framework, linked to ammonite zonations defined by genera described by paleontologists affiliated with the Geological Survey of Italy and comparative work comparing the Carnian succession in the Dolomites to sequences in the Sierra de Córdoba and Queen Charlotte Islands. Regional chronostratigraphic charts produced by the Geological Society of America and the Geological Society of London integrate these subdivisions with isotopic tie points from volcanic ash beds dated by teams at the University of California, Berkeley and ETH Zurich.
Geology and Paleoenvironments
Carnian deposits record siliciclastic, carbonate, and volcaniclastic facies across rift basins and passive margins, reflecting tectonism associated with the breakup of Pangea and magmatism linked to the Wrangellia large igneous province and other volcanic provinces. Marine carbonate platforms of the Tethys Ocean show reef and inner-shelf buildups comparable to those studied in the Dolomites and Apennines, while coeval continental redbeds and fluvial sequences exposed in the Ischigualasto Formation, Chinle Formation, and Buntsandstein record alluvial and lacustrine environments documented by field teams from the Smithsonian Institution and the University of Buenos Aires. Geochemical proxies from cores drilled by the Deep Sea Drilling Project and isotope laboratories at Scripps Institution of Oceanography capture shifts in seawater chemistry and sedimentation patterns.
Paleontology and Biotic Changes
The Carnian hosts important turnovers among marine invertebrates—ammonoids, conodonts, bivalves—and marked radiations among archosauromorphs and early dinosauromorphs documented in faunas from the Ischigualasto Formation, Santa Maria Supersequence, and Adamanian-equivalent strata. Plant assemblages including bennettitaleans and cheirolepidiaceous conifers described by paleobotanists at the Natural History Museum and the Royal Botanic Gardens, Kew show diversification concurrent with insect herbivore expansion referenced in studies from the Natural History Museum, London and the American Museum of Natural History. Marine microfossil turnovers in radiolarians and foraminifera correlate with biotic events recognized in works by researchers at the University of Tokyo and CNRS teams in France.
Carnian Pluvial Episode
The Carnian Pluvial Episode (CPE) is a globally recognized humid event marked by increased precipitation, runoff, and sediment flux documented in terrestrial basins such as the Newark Basin, Ischigualasto-Villa Unión Basin, and Karoo Basin. The CPE coincides with carbon cycle perturbations recorded in organic carbon and carbonate isotopes analyzed at the University of Leeds and ETH Zurich, and with volcanic forcing implicated through ash layers linked to Wrangellia magmatism and elevated atmospheric greenhouse gas inferred from climate modeling studies by groups at the Met Office and Max Planck Institute for Chemistry. Palynological and sedimentological shifts during the CPE are central to interpretations advanced by teams at the University of Oxford, University of Milan, and University of São Paulo.
Chronostratigraphic Correlation and Global Sections
Correlation of Carnian successions relies on integrating ammonoid zonation, conodont biostratigraphy, magnetostratigraphy, and radiometric ages from GSSP candidates in the Southern Alps and other reference sections in the Tethyan realm. International collaboration coordinated by the International Union of Geological Sciences and ICS working groups links classic Mediterranean stratotypes to sequences in the Rocky Mountains, Karoo Supergroup, and Sierra Nevada through chemostratigraphy and ammonoid correlations developed by researchers at the University of Milan, Birkbeck, University of London, and the University of New South Wales.
Economic and Paleoclimatic Significance
Carnian strata host hydrocarbon source and reservoir rocks in basins such as the Gulf of Mexico margin, North Sea, and rift basins evaluated by energy companies and researchers at the Norwegian Petroleum Directorate and British Geological Survey. Evaporite and carbonate deposits in the Mediterranean and Western Interior are significant for mineral resources studied by economic geologists at the University of Edinburgh and Colorado School of Mines. Paleoclimatic reconstructions from Carnian records inform models of greenhouse climates, used by climatologists at the IPCC-affiliated centers and climate modeling groups at the National Center for Atmospheric Research and Lamont–Doherty Earth Observatory to understand long-term Earth system responses to volcanism and orbital forcing.