Wikipedia

Rødvig Formation

The Rødvig Formation is a geological formation deposited during the earliest part of the Danian (early Paleocene; c. 65-62 Ma[1]) and it was first identified by Richard Taylor and Richard Phillips in 1827.[2] It is known from exposures at Stevns Klint in Denmark. The unit lies directly above the K–Pg boundary and contains fossils that provide a record of the recovery of various groups following the Cretaceous–Paleogene extinction. The upper boundary of the formation is an unconformity in the form of a hardground, beneath which the formation is sometimes missing. The base of the unit is irregular due to the presence of mounding associated with bryozoa, causing variations in thickness. The unit is subdivided into the lower Fiskeler Member mainly formed of marl and the overlying Cerithium Limestone Member.[3]

Rødvig Formation
Stratigraphic range: Danian
~65–62 Ma
↓
[1]
Stevns Klint, where the Rødvig Formation outcrops
TypeGeological formation
Unit ofChalk Group/Danienkalk
Sub-unitsFiskeler Member, Cerithium Limestone Member
UnderliesStevns Klint Formation
OverliesTor Formation
Thickness10 centimetres (3.9 in) to 30 centimetres (12 in)
Lithology
PrimaryBryozoa chalk and dark clay
OtherLimestone and marl
Location
RegionZealand
CountryDenmark
ExtentStevns Klint
Type section
Named byRichard Taylor and Richard Phillips
Year defined1827

Geology edit

 
The three fossil formations of Stevns Klint, with the Rødvig Formation in the middle

The dark layer of fiskeler,[a] mainly five to ten centimeters thick, clearly marks the Cretaceous–Paleogene boundary and overlies the Maastrichtian age Tor Formation.[5] The fiskeler is enriched in iridium, a fact used as an argument for the Alvarez hypothesis that the worldwide Cretaceous–Paleogene mass extinction was caused by the impact of an asteroid. Following the boundary is a layer of darker clay and chalk between 10 and 30 cm thick, corresponding to a period of low biological diversity on the sea floor immediately after the K-Pg Boundary.[6]

Paleontology edit

The Rødvig Formation contains a remarkably detailed and complete fossil record of the biota in Northern Europe during the early Paleogene. The layers are rich in microfossils, containing many species of millimeter-long suspension feeders.[7] A wide variety of benthic foraminifera species have been identified from the Rødvig Formation, with significant differences in abundance across the K–Pg boundary demonstrating the biotic turnover that occurred during the mass extinction event.[7]

Ammonites edit

See also: Paleocene ammonites

The Rødvig Formation was the first known site to document the short-term survival of ammonites into the Paleogene, when they were originally thought to have gone extinct at the K-Pg boundary.[8][9][10][11][12][13] Ammonites are thus only known from the first 200,000 years of the Cerithium Limestone, before disappearing from the formation around 64.8 million years ago.[10][13]

Two ammonite species are known from the Rødvig Formation: Baculites vertebralis, notable for having a nearly straight shell,[14] and Hoploscaphites constrictus, which may have been a subspecies of Scaphites,[15] and is also the most common ammonite known from the Paleocene.[9][10]

Known fossil fauna edit

The known fossil fauna found in the Rødvig Formation includes:[16][17][18]

References edit

  1. ^ A Danish word that is traditionally used by geologists as a label for this layer, parallel to its English translation "Fish Clay". It was given this name by the Danish geologist Johan Georg Forchhammer in 1825, as it contained scales and teeth from fish, but few other fossils.[4][full citation needed]
  1. ^ a b Surlyk F, Damholt T. & Bjerager M. (2006). "Stevns Klint, Denmark: Uppermost Maastrichtian chalk, Cretaceous-Tertiary boundary, and lower Danian bryozoan mound complex" (PDF). Bulletin of the Geological Society of Denmark. 54: 1–48. doi:10.37570/bgsd-2006-54-01.
  2. ^ Taylor, R. & Phillips, R. (1827). The Philosophical magazine, or Annals of chemistry, mathematics, astronomy, natural history and general science. London : Richard Taylor (p. 99)
  3. ^ Surlyk, F.; Damholt, T.; Bjerager, M. (2006). "Stevns Klint, Denmark: Uppermost Maastrichtian chalk, Cretaceous–Tertiary boundary, and lower Danian bryozoan mound complex". Bulletin of the Geological Society of Denmark. 54: 1–48. doi:10.37570/bgsd-2006-54-01.
  4. ^ Syrlyk, Damholt & Bjerager pages 29 and 31.
  5. ^ "Stevns Klint". Den Store Danske (in Danish). Retrieved 23 June 2014.
  6. ^ International Union on Conservation of Nature (March 2014). World Heritage Nomination - IUCN Technical Evaluation: Stevns Klint (Denmark) - ID No. 1416 (Report). UNESCO.
  7. ^ a b Heritage Agency of Denmark (January 2012). Nomination of Stevns Klint (PDF) (Report). UNESCO. Retrieved 27 Jun 2021.
  8. ^ Heritage Agency of Denmark (January 2012). Nomination of Stevns Klint (PDF) (Report). UNESCO. Retrieved 27 Jun 2021.
  9. ^ a b Landman, Neil H.; Goolaerts, Stijn; Jagt, John W.M.; Jagt-Yazykova, Elena A.; Machalski, Marcin (2015), Klug, Christian; Korn, Dieter; De Baets, Kenneth; Kruta, Isabelle (eds.), "Ammonites on the Brink of Extinction: Diversity, Abundance, and Ecology of the Order Ammonoidea at the Cretaceous/Paleogene (K/Pg) Boundary", Ammonoid Paleobiology: From macroevolution to paleogeography, Topics in Geobiology, vol. 44, Dordrecht: Springer Netherlands, pp. 497–553, doi:10.1007/978-94-017-9633-0_19, ISBN 978-94-017-9632-3, retrieved 2021-10-26
  10. ^ a b c d e Machalski, Marcin; Heinberg, Claus (2005-12-01). "Evidence for ammonite survival into the Danian (Paleogene) from the Cerithium Limestone at Stevns Klint, Denmark". Bulletin of the Geological Society of Denmark. 52: 2005–12. doi:10.37570/bgsd-2005-52-08.
  11. ^ Machalski, M.; Jagt, J. W. M.; Heinberg, C.; Landman, N. H.; Hakansson, E. (2009). "Dańskie amonity - obecny stan wiedzy i perspektywy badań". Przegląd Geologiczny (in Polish). 57 (6): 486–493. ISSN 0033-2151.
  12. ^ W. M. Jagt, John (2012-01-01). "Ammonieten uit het Laat-Krijt en Vroeg-Paleogeen van Limburg". Grondboor & Hamer. 66 (1): 154–183.
  13. ^ a b "Late Maastrichtian and earliest Danian scaphitid ammonites from central Europe: Taxonomy, evolution, and extinction - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 2021-10-26.
  14. ^ Westermann, G. E. G. (1996). Ammonoid life and habitat. In N. H. Landman, K. Tanabe, and R. A. Davis (editors), Ammonoid Paleobiology, pp. 607–707. New York: Plenum Press.
  15. ^ Hoploscaphites at Fossilworks.org
  16. ^ "Rødvig - Cerithium Limestone, Aalborg, North Jutland Region, Denmark". Mindat.org. Retrieved 24 August 2022.
  17. ^ Adolfssen et al. 2017
  18. ^ Heinberg, C. (1999). "Lower Danian bivalves, Stevns Klint, Denmark: Continuity across the K/T boundary". Palaeogeography, Palaeoclimatology, Palaeoecology. 154 (1–2): 87–106. Bibcode:1999PPP...154...87H. doi:10.1016/S0031-0182(99)00088-7.
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