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| Selandian | |
|---|---|
| Name | Selandian |
| Color | #CCCCFF |
| Time start | 61.6 |
| Time end | 59.2 |
| Time unit | Ma |
| Preceding | Danian |
| Following | Thanetian |
| Era | Paleocene |
| Named for | Zealand |
| Named by | S. S. A. de Lapparent |
Selandian is an interval of the Paleocene Epoch within the Paleogene Period that succeeds the Danian and precedes the Thanetian. It is recognized in international stratigraphy and regional chronostratigraphic schemes across Europe, North America, Asia, Africa, and Australasia. The interval is important for understanding early Cenozoic recovery after the Cretaceous–Paleogene extinction event and for correlating marine and continental sequences worldwide.
The stage was established on the basis of stratotypes in Denmark and named for deposits on Zealand near Copenhagen, with ties to classical sections in the North Sea Basin and Danish Basin. The lower boundary is set above key planktonic and benthic foraminiferal turnovers recorded in sections correlated to the Fleensborg Formation and to the Palaeocene stratigraphy of the Cretaceous Research Group frameworks. The upper limit is defined by biostratigraphic markers that tie into sequences in the Paris Basin, North Sea, and New Jersey coastal plain occurrences. International subdivisions link the stage to magnetostratigraphic chrons used in the Geologic Time Scale and to biozones employed by the International Commission on Stratigraphy.
Absolute ages for the interval derive from radiometric dates from Greenland volcanic ash layers, Dorset tuffs, and dated igneous horizons in the Basque-Cantabrian Basin, integrated with magnetostratigraphy from the Vøring Plateau and Rockall Basin. Current calibrations place the start near 61.6 Ma and the end near 59.2 Ma on the International Chronostratigraphic Chart; these derive from U–Pb zircon dating, 40Ar/39Ar measurements from sanidine, and correlation to Geomagnetic Polarity Time Scale chrons, including chrons C26r and C27n. Studies using stable isotope excursions, especially δ13C shifts recorded in sections from the Paris Basin, Shatsky Rise, and North Atlantic Igneous Province, assist correlation with global events like the Paleocene Thermal Maximum-adjacent fluctuations.
Selandian strata show lithologic variability from carbonate-bearing marine marls and nannofossil chalks in the North Sea Basin and English Channel to siliciclastic mudstones and deltaic sands in the Southeastern United States and Ganges Basin. Marine successions in the Paris Basin, Holland, and Belgium feature calcareous nannofossil ooze, benthic foraminiferal limestones, and sequence-bounding unconformities analogous to those in the Baltic Basin and Iberian Basin. Continental sequences in the Williston Basin, Powell Basin, and parts of India contain fluvial conglomerates, levee sands, paleosols and lignite seams correlated to coastal plain transgression-regression cycles documented in cores from the New Jersey Coastal Plain and the Saskatchewan portion of the Western Canadian Sedimentary Basin.
Fossil assemblages include diversification and turnover among planktonic foraminifera, calcareous nannoplankton, and benthic foraminifera recorded in the Flemish Cap, Newfoundland Basin, and North Atlantic Drift deposits. Marine invertebrate faunas—such as bivalvia and gastropoda—show provinciality comparable to faunas from the Paris Basin and English Channel shelves. Terrestrial vertebrate assemblages in the Riversleigh deposits, Arshantan-equivalent sequences in Central Asia, and North American localities document mammalian radiation among groups that later dominate the Eocene faunas, with links to records from the Willwood Formation and Bighorn Basin. Palynological records from the Paleocene–Eocene transition in Greenland and Antarctica help track floral turnover involving taxa comparable with those in the London Clay and Fur Formation.
Regional stage equivalents and substage frameworks correlate Selandian deposits to subdivisions used in the European Neogene and Quaternary stratigraphy context, and to North American land mammal ages such as intervals adjacent to the Puercan and Torrejonian in parts of New Mexico and Montana. In marine contexts, correlations tie Selandian units to nannoplankton biozones and to magnetostratigraphic chrons employed across the North Atlantic, South Atlantic, Indian Ocean and Tethys realms. Subdivision schemes in the Netherlands and Denmark use local member names that match lithostratigraphic units in the Vendee and Saxon Basin, while Asian correlations link to sequences in Shanxi and the Gobi Desert.
The stage name originated from Danish geologists who worked on Paleocene strata near Copenhagen and in the Kattegat region; subsequent work by researchers from institutions such as Natural History Museum, London, Geological Survey of Denmark and Greenland, U.S. Geological Survey, and universities in Paris, Uppsala, Berlin, Leiden, Münster, and Tokyo refined boundaries. Key contributors included regional stratigraphers who integrated biostratigraphy, magnetostratigraphy and radiometric dating—methodological advances paralleled by collaborations with teams at Lamont–Doherty Earth Observatory, GFZ German Research Centre for Geosciences, CNRS, University of Cambridge, Harvard University, University of California, Berkeley, and University of Copenhagen. Ongoing debates over precise numeric ages and global tie points involve working groups of the International Commission on Stratigraphy and multidisciplinary programs including ocean drilling initiatives like ODP and ICDP projects.