Selandian

From Wikipedia, the free encyclopedia
Jump to: navigation, search
System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
Neogene Miocene Aquitanian younger
Paleogene Oligocene Chattian 23.03–28.1
Rupelian 28.1–33.9
Eocene Priabonian 33.9–38.0
Bartonian 38.0–41.3
Lutetian 41.3–47.8
Ypresian 47.8–56.0
Paleocene Thanetian 56.0–59.2
Selandian 59.2–61.6
Danian 61.6–66.0
Cretaceous Upper/
Late
Maastrichtian older
Subdivision of the Paleogene Period
according to the ICS, as of January 2013.[1]

The Selandian is in the geologic timescale an age or stage in the Paleocene. It spans the time between 61.6 and 59.2 Ma. It is preceded by the Danian and followed by the Thanetian.[1] Sometimes the Paleocene is subdivided in subepochs, in which the Selandian forms the "Middle Paleocene".

Stratigraphic definition[edit]

The Selandian was introduced in scientific literature by Alfred Rosenkrantz in 1924. It is named after the Danish island of Zealand (Danish: Sjælland).

The base of the Selandian is close to the boundary between biozones NP4 and NP5. It is slightly after the first appearances of many new species of the calcareous nannoplankton genus Fasciculithus (F. ulii, F. billii, F. janii, F. involutus, F. tympaniformis and F. pileatus) and close to the first appearance of calcareous nannoplankton species Neochiastozygus perfectus. At the original type location in Denmark the base of the Selandian is an unconformity. The official GSSP was established in the Zumaia section (43° 18'N, 2° 16'W) at the beach of Itzurun, Pais Vasco, northern Spain.[2]

The top of the Selandian (the base of the Thanetian) is laid at the base of magnetic chronozone C26n.

The Selandian stage overlaps with the lower part of the Tiffanian North American Land Mammal Age, the Peligran, Tiupampan and lower Itaboraian South American Land Mammal Ages and part of the Nongshanian Asian Land Mammal Age. It is coeval with the lower part of the Wangerripian stage from the Australian regional timescale.

Fauna and Flora[edit]

The fauna of the Selandian consisted of giant snakes (Titanoboa),[3] crocodiles, champosaurs, Gastornithiformes[4] Owls; while the mammalian fauna was composed of a few archaic forms of mammals, such as Mesonychids, Pantodonts, primate relatives Plesiadapids, and Multiberculates.

The flora was composed of cacti, ferns, angiosperms, and palm trees.

References[edit]

Notes[edit]

  1. ^ a b Cohen, K.M., Finney, S., Gibbard, P.L. (2013), International Chronostratigraphic Chart, International Commission on Stratigraphy .
  2. ^ See for example Arenillas et al. (2008) or Bernaola et al. (2009) for a description of the Danian-Selandidan boundary
  3. ^ Kwok, R. (4 February 2009). "Scientists find world's biggest snake". Nature News. doi:10.1038/news.2009.80. 
  4. ^ See for example (Koeberl C., Macleod K, Catastrophic Events and Mass Extinctions: Impacts and Beyond, pp. 305, pp. 304)

Literature[edit]

  • Arenillas, I.; Molina, E.; Ortiz, S. & Schmitz, B.; 2008: Foraminiferal and δ13C isotopic event-stratigraphy across the Danian-Selandian transition at Zumaya (northern Spain): chronostratigraphic implications, Terra Nova 20: pp 38–44.
  • Bernaola, G., Martín-Rubio, M. & Baceta, J.I., 2009: New high resolution calcareous nannofossil analysis across the Danian-Selandian transition at the Zumaia section: comparisons with South Tethys and Danish sections, Geologica Acta 7(1-2), pp 79–92.
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Rosenkrantz, A.; 1920: En ny københavnsk Lokalitet for forsteningsførende Paleocæn, Meddelelser fra Dansk Geologisk Forening 5, pp. 1–10 (published March 1921). (Danish)
  • Rosenkrantz, A.; 1924: De københavnske Grønsandslag og deres Placering i den danske Lagrække. Meddelelser fra Dansk Geologisk Forening 6, pp. 1–39. (Danish)

External links[edit]

Coordinates: 43°18′02″N 2°15′34″W / 43.30056°N 2.25944°W / 43.30056; -2.25944