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Rødvig Formation

{{Short description|Geological formation in Denmark}}

{{Infobox rockunit

|name = Rødvig Formation

|image = Stevns_Klint_Juli_2019.jpg

|caption = Stevns Klint, where the Rødvig Formation outcrops

|type = Geological formation

|age = Danian
~{{fossilrange|65|62}}{{cite journal | url=http://2dgf.dk/xpdf/bull54.pdf | title=Stevns Klint, Denmark: Uppermost Maastrichtian chalk, Cretaceous-Tertiary boundary, and lower Danian bryozoan mound complex | author=Surlyk F, Damholt T. & Bjerager M. | journal=Bulletin of the Geological Society of Denmark | year=2006 | volume=54 | pages=1–48| doi=10.37570/bgsd-2006-54-01}}

|period = Danian

|prilithology = Bryozoa chalk and dark clay|otherlithology=Limestone and marl

|namedfor =

|namedby = Richard Taylor and Richard Phillips

|year_ts = 1827

|region = Zealand

|country = Denmark

|coordinates =

|unitof = Chalk Group/Danienkalk

|subunits = Fiskeler Member, Cerithium Limestone Member

|underlies = Stevns Klint Formation

|overlies = Tor Formation

|thickness = {{convert|10|cm|in}} to {{convert|30|cm|in}}

|extent = Stevns Klint

|area =

|map =

|map_caption =

}}

The Rødvig Formation is a geological formation deposited during the earliest part of the Danian (early Paleocene; {{circa|65-62 Ma}}) and it was first identified by Richard Taylor and Richard Phillips in 1827.Taylor, R. & Phillips, R. (1827). The Philosophical magazine, or Annals of chemistry, mathematics, astronomy, natural history and general science. London : Richard Taylor (p. 99) 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.{{Cite journal |last1=Surlyk |first1=F. |last2=Damholt |first2=T. |last3=Bjerager |first3=M. |date=2006 |title=Stevns Klint, Denmark: Uppermost Maastrichtian chalk, Cretaceous–Tertiary boundary, and lower Danian bryozoan mound complex |journal=Bulletin of the Geological Society of Denmark |volume=54 |pages=1–48 |doi=10.37570/bgsd-2006-54-01|doi-access=free }}

Geology

File:Stevns_Klint_Fossil_Formations.png, with the Rødvig Formation in the middle]]

The dark layer of {{lang|da|fiskeler}},{{efn|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.Syrlyk, Damholt & Bjerager pages 29 and 31.{{full citation needed|date=January 2020}}}} mainly five to ten centimeters thick, clearly marks the Cretaceous–Paleogene boundary and overlies the Maastrichtian age Tor Formation.{{cite encyclopedia |title=Stevns Klint |encyclopedia=Den Store Danske |url=http://www.denstoredanske.dk/It,_teknik_og_naturvidenskab/Geologi_og_kartografi/Danmark,_Kridt/Stevns_Klint?highlight=stevns%20klint |access-date=23 June 2014 |language=da}} The {{lang|da|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.{{cite report |url=http://whc.unesco.org/en/list/1416/documents/ |title=World Heritage Nomination - IUCN Technical Evaluation: Stevns Klint (Denmark) - ID No. 1416 |author=International Union on Conservation of Nature |date=March 2014 |publisher=UNESCO}}

Paleontology

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.{{cite report |url=http://whc.unesco.org/uploads/nominations/1416.pdf |title=Nomination of Stevns Klint |author=Heritage Agency of Denmark |date=January 2012 |publisher=UNESCO |access-date=27 Jun 2021}} 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.

= Ammonites =

{{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.{{cite report |url=http://whc.unesco.org/uploads/nominations/1416.pdf |title=Nomination of Stevns Klint |author=Heritage Agency of Denmark |date=January 2012 |publisher=UNESCO |access-date=27 Jun 2021}}{{Citation |last1=Landman |first1=Neil H. |title=Ammonites on the Brink of Extinction: Diversity, Abundance, and Ecology of the Order Ammonoidea at the Cretaceous/Paleogene (K/Pg) Boundary |date=2015 |url=http://link.springer.com/10.1007/978-94-017-9633-0_19 |work=Ammonoid Paleobiology: From macroevolution to paleogeography |volume=44 |pages=497–553 |editor-last=Klug |editor-first=Christian |place=Dordrecht |publisher=Springer Netherlands |language=en |doi=10.1007/978-94-017-9633-0_19 |isbn=978-94-017-9632-3 |access-date=2021-10-26 |last2=Goolaerts |first2=Stijn |last3=Jagt |first3=John W.M. |last4=Jagt-Yazykova |first4=Elena A. |last5=Machalski |first5=Marcin |series=Topics in Geobiology |editor2-last=Korn |editor2-first=Dieter |editor3-last=De Baets |editor3-first=Kenneth |editor4-last=Kruta |editor4-first=Isabelle|url-access=subscription }}{{Cite journal |last1=Machalski |first1=Marcin |last2=Heinberg |first2=Claus |date=2005-12-01 |title=Evidence for ammonite survival into the Danian (Paleogene) from the Cerithium Limestone at Stevns Klint, Denmark |url=https://www.researchgate.net/publication/261359356 |journal=Bulletin of the Geological Society of Denmark |volume=52 |pages=2005–12 |doi=10.37570/bgsd-2005-52-08|doi-access=free }}{{Cite journal |last1=Machalski |first1=M. |last2=Jagt |first2=J. W. M. |last3=Heinberg |first3=C. |last4=Landman |first4=N. H. |last5=Hakansson |first5=E. |date=2009 |title=Dańskie amonity - obecny stan wiedzy i perspektywy badań |url=http://yadda.icm.edu.pl/baztech/element/bwmeta1.element.baztech-article-BUS6-0017-0038 |journal=Przegląd Geologiczny |language=PL |volume=57 |issue=6 |pages=486–493 |issn=0033-2151}}{{Cite journal |last=W. M. Jagt |first=John |date=2012-01-01 |title=Ammonieten uit het Laat-Krijt en Vroeg-Paleogeen van Limburg |url=https://natuurtijdschriften.nl/pub/1000190 |journal=Grondboor & Hamer |language=en |volume=66 |issue=1 |pages=154–183}}{{Cite web |title=Late Maastrichtian and earliest Danian scaphitid ammonites from central Europe: Taxonomy, evolution, and extinction - Acta Palaeontologica Polonica |url=https://www.app.pan.pl/article/item/app50-653.html |access-date=2021-10-26 |website=www.app.pan.pl}} 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.

Two ammonite species are known from the Rødvig Formation: Baculites vertebralis, notable for having a nearly straight shell,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. and Hoploscaphites constrictus, which may have been a subspecies of Scaphites,[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=15015 Hoploscaphites] at Fossilworks.org and is also the most common ammonite known from the Paleocene.

Known fossil fauna

The known fossil fauna found in the Rødvig Formation includes:{{cite web|title=Rødvig - Cerithium Limestone, Aalborg, North Jutland Region, Denmark|url=https://www.mindat.org/paleo_strat.php?id=14475|publisher=Mindat.org|access-date=24 August 2022}}[https://2dgf.dk/xpdf/bull65-1-23.pdf Adolfssen et al. 2017]{{cite journal | url=https://www.sciencedirect.com/science/article/pii/S0031018299000887 | doi=10.1016/S0031-0182(99)00088-7 | title=Lower Danian bivalves, Stevns Klint, Denmark: Continuity across the K/T boundary | year=1999 | last1=Heinberg | first1=C. | journal=Palaeogeography, Palaeoclimatology, Palaeoecology | volume=154 | issue=1–2 | pages=87–106 | bibcode=1999PPP...154...87H | url-access=subscription }}

References

{{reflist|group=lower-alpha}}

Category:Danian

Category:Danian Stage

Category:Geology of Denmark