Danian
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| Danian | |
|---|---|
| Name | Danian |
| Color | #FFD700 |
| Period | Paleocene |
| Epoch | Paleogene |
| Time start mya | 66.0 |
| Time end mya | 61.6 |
| Caption | Danian chalk and marl sequences |
Danian The Danian is the lowermost age and stage of the Paleocene Epoch, traditionally placed immediately after the Cretaceous–Paleogene boundary. It marks a major turnover following the end-Cretaceous extinction and is used in international stratigraphic charts to correlate successions worldwide. Prominent stratotypes and reference sections from Europe, North America, Africa, and Asia anchor its definition in global lithostratigraphic and biostratigraphic frameworks.
Definition and Stratigraphic Placement
The Danian was originally defined on the basis of stratotypes in the Maastrichtian–Paleocene transition near the town of Dania (type area) and formalized under the International Commission on Stratigraphy (ICS), tied to the Global Boundary Stratotype Section and Point (GSSP) concept. Key correlatives include the Danian Stage as the basal unit of the Paleocene Series and the lower Paleocene chronozones used in magnetostratigraphy such as Chron C29r. Interregional correlations employ index taxa and chemostratigraphic markers from sections recognized by organizations including the International Union of Geological Sciences and regional surveys like the United States Geological Survey and British Geological Survey. The boundary that defines the base of the Danian is commonly associated with iridium anomalies originally documented in sections studied by teams led by Walter Alvarez and colleagues in relation to the Chicxulub impact and associated ejecta layers identified on the Yucatán Peninsula and Gulf Coast sections analyzed by the Geological Society of America and paleolimnological studies.
Geological and Paleontological Characteristics
Danian strata are characterized by chalks, marls, shallow-marine limestones, siliciclastic successions, and continental deposits described in publications from institutions such as the Natural History Museum, Smithsonian Institution, and CNRS. Fossil assemblages include benthic and planktonic foraminifera used by micropaleontologists at universities like Cambridge, Oxford, and Columbia, as well as nannofossil floras cataloged by researchers affiliated with the Geological Society of London and Paleontological Society. Geochemical signals such as δ13C excursions, oxygen isotope shifts, and trace element anomalies have been investigated by teams at institutions including MIT, ETH Zurich, and the Max Planck Institute, and are documented alongside stratigraphic logs from the Royal Netherlands Institute for Sea Research and the Lamont–Doherty Earth Observatory.
Global Distribution and Regional Stages
Danian deposits are broadly distributed across Europe, North America, South America, Africa, Asia, and Australasia. Regional equivalents and stages include the Puercan and Torrejonian North American Land Mammal Ages defined by the American Museum of Natural History and USGS paleontologists, the Tiffanian correlations in North America, the Paleocene sections of the Paris Basin studied by CNRS teams, the Rødby Formation exposures recognized by Danish geological surveys, and the Nacimiento Formation investigated by New Mexico Bureau of Geology. In South America, comparable successions are correlated with sequences examined by Argentinian and Brazilian stratigraphers; African correlations involve sections from Morocco and Niger documented by universities such as Rabat and Niamey. Asian correlations reference sequences from the Indian subcontinent studied at the Geological Survey of India and Chinese Danian-equivalent formations described by the Chinese Academy of Sciences.
Fossil Record and Biotic Recovery
The Danian fossil record records early Paleocene recovery trajectories for terrestrial and marine biotas after the K–Pg event, with mammalian faunas monitored by paleontologists at the American Museum of Natural History and University of Chicago, avian records examined by researchers at the Natural History Museum, and floral changes documented by palynologists at Utrecht and the University of Copenhagen. Marine recovery is traced through planktonic foraminifera turnover studied at the University of Texas and nannoplankton research by teams at the University of Barcelona and Sorbonne. Notable vertebrate groups include early placentals and marsupials whose histories are reconstructed using collections from the Field Museum and Smithsonian Institution, while invertebrate recovery and reef reestablishment are reported in journals associated with the Geological Society of America and Paleontological Research institutions in Japan and Australia.
Chronostratigraphy and Dating Methods
Danian chronology integrates biostratigraphy, magnetostratigraphy, chemostratigraphy, and radiometric dating produced by laboratories such as the Berkeley Geochronology Center and the Australian National University. High-resolution age models employ 40Ar/39Ar dates from volcanic ash layers analyzed at facilities like GFZ Potsdam and geochemical correlation to the gradual recovery curve recognized in isotope datasets compiled by NOAA and PANGAEA-hosted studies. Magnetochronological frameworks reference polarity chrons such as C29r and C30n correlated with international polarity timescales maintained by the International Union of Geodesy and Geophysics and ICS publications.
Historical Usage and Nomenclature
The term Danian has evolved since its introduction in early 20th-century European stratigraphy and was adopted in modern stratigraphic codes following proposals discussed at ICS meetings and International Geological Congress sessions. Key contributions to its nomenclatural history come from stratigraphers affiliated with institutions such as the British Geological Survey, the Royal Society, and national geological surveys of Denmark, France, and the United States, and through synthesis works published by Cambridge University Press and Springer. Debates over boundaries, subdivisions, and regional stage equivalence continue in symposia convened by organizations including the International Paleontological Association and the Palaeontological Association.