imported>Volcanoguy: removed Category:Geography of Antwerp Province; added Category:Antwerp Province using HotCat

2025-06-27T21:47:35Z

removed Category:Geography of Antwerp Province; added Category:Antwerp Province using HotCat

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{{short description|Geologic formation in Belgium}}
{{Infobox rockunit
| name = Ieper Group<br>Groupe d'Ypres
| period = Ypresian
| age = [[Ypresian]]<br>~{{fossil range|54|50}}
| image =
| imagesize =
| caption =
| type = [[Geologic group]]
| prilithology = [[Sandstone]], [[claystone]]
| otherlithology = [[Siltstone]]
| unitof =
| subunits = [[Kortrijk Formation|Kortrijk]], [[Mons-en-Pévèle Formation|Mons-en-Pévèle]], [[Tielt Formation|Tielt]], [[Hyon Formation|Hyon]] & [[Gentbrugge Formation]]s
| underlies = [[Zenne Group]]<br> [[Aalter Formation]]
| overlies = [[Landen Group]]<br> [[Tienen Formation]]
| thickness = >{{convert|225|m|ft|abbr=on}}
| location =
| coordinates = {{coord|51.3|N|4.3|E|display=inline,title}}
| paleocoordinates = {{coord|46.7|N|1.5|E|display=inline}}
| region = [[East Flanders]], [[West Flanders]], [[Antwerp (province)|Antwerp]], [[Hainaut (province)|Hainaut]], [[Flemish Brabant|Flemish]] & [[Walloon Brabant]]
| country = [[Belgium]]
| extent = [[Campine Basin]]
| namedfor = [[Ypres]] (Ieper)
| namedby =
| year_ts =
| location_ts =
| coordinates_ts =
| paleocoordinates_ts =
| region_ts =
| country_ts =
| thickness_ts =
| area =
| map = {{Location map+ | Belgium
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | Belgium
| lat_deg = 51.3
| lon_deg = 4.3
| mark = Orange pog.svg
| marksize = 12
}}
}}
| map_caption =
}}
The '''Ieper Group''' ({{langx|nl|Ieper Groep}}; {{langx|fr|Groupe d'Ypres}}) is a [[group (stratigraphy)|group]] of [[stratum|rock strata]] in the [[Subsurface (geology)|subsurface]] of northwest [[Belgium]]. The group is subdivided into three [[marine (ocean)|marine]] [[formation (stratigraphy)|formations]], all formed during the [[Ypresian]], a single [[age (geology)|age]] of the [[geologic timescale]] (55.8 to 48.6 million years ago, the oldest age of the [[Eocene]] [[Epoch (geology)|epoch]]). Both age and group are named after the [[West Flanders|West Flemish]] town of [[Ypres]], for which the [[Dutch language|Dutch]] name is "Ieper".

== History of definition ==
=== Ypresian ===
{{main|Ypresian}}
{{see also|:Category:Ypresian Stage|:Category:Ypresian life}}
In the original description of his newly introduced Ypresian stage Dumont (1850) did mention neither stratotype nor type locality. He simply referred to the "collines d'Ypres" or Ieper Hills, as the area where the unit is best developed. However, it remains unclear what is meant by this term. The town of Ieper is situated in western Belgium, at the southern end of a small, NW-SE oriented depression ({{convert|15|to|20|m|ft}} above mean sea level), surrounded from north to south by a series of low hills (between {{convert|25|and|45|m|ft}}). Dumont probably envisaged the elevated zones a few km north and east of Ieper (St.-Jan, Zillebeke, etc.), where clay beds have been quarried for brick and tile making for quite a long time.<ref name=Steurbaut2006-p74>Steurbaut, 2006, p.74</ref>

A new stratotype for the Lutetian was proposed by Blondeau (1981) about {{convert|50|km|mi}} north of Paris. The neostratotype is located on the right bank of the river [[Oise River|Oise]] at [[St. Leu d'Esserent]] and the large quarry at [[St. Vaast-les-Mello]] ([[Oise Department|Oise]]).<ref name=Molina2006-p15>Molina et al., 2006, p.15</ref>

Since 2003, the [[Global Stratotype Section and Point]] (GSSP) defined by the [[International Commission on Stratigraphy]] (ICS) for the Ypresian is set in the Dababiya section close to Luxor, Egypt,<ref name=Britannica>[https://www.britannica.com/science/Ypresian-Stage Ypresian Stage] at [[Encyclopedia Britannica]]</ref> where the uppermost [[Tarawan Limestone]], the [[Esna Formation]] and the lowermost [[Thebes Limestone]] define the Ypresian sequence.<ref name=Dupuis2003-p44>Dupuis et al., 2003, p.44</ref> Several other proposals for the lithostratigraphic redefinition of the top of the Ypresian exist;<ref name=Unizar/> among others the [[Punta Torcida Formation]] of the [[Magallanes Basin|Austral or Magallanes Basin]] in [[Tierra del Fuego]], the [[Azkorri Sandstone]] in the Gorrondatxe section of the [[North Pyrenean Foreland Basin|North Pyrenean Foreland]] or [[Basque–Cantabrian Basin]],<ref name=Bernaola2006-p75>Bernaola et al., 2006, p.75</ref><ref name=Larrasoana2008-p396>Larrasoaña et al., 2008, p.396</ref> the Agost section close to [[Alicante]] in the [[Agost Basin]] in the [[Betic Cordillera]],<ref name=Larrasoana2008-p411>Larrasoaña et al., 2008, p.411</ref> and the Fortuna section north of [[Murcia]] in the Prebetic realm of the Betic Cordillera,<ref name=Molina2006-p8>Molina et al., 2006, p.8</ref><ref name=Guerrera2014-p172>Guerrera et al., 2014, p.172</ref> all in Spain. Other proposed type sections for the Ypresian-Lutetian boundary are located in France, Italy, Israel, Tunisia, Morocco, Cuba and Mexico.<ref name=Unizar>[http://wzar.unizar.es/perso/emolina/ypresian.html Ypresian/Lutetian boundary stratotype] - [[University of Zaragoza]]</ref><ref name=Molina2006-p2>Molina et al., 2006, p.2</ref>

=== Stratigraphy ===
The Ieper Group was redefined by Steurbaut in 2006,<ref name=Steurbaut2006-p76>Steurbaut, 2006, p.76</ref> and is since 2017 subdivided into five formations by the National Commission for the Stratigraphy of Belgium, from youngest to oldest:<ref name=NCSB>[https://ncs.naturalsciences.be/paleogene-neogene/ieper-group Ieper Group] - National Commission for the Stratigraphy of Belgium</ref>

{| class="wikitable sortable"
! Age !! [[Magnetostratigraphy|Chron]] !! Group !! Formation !! Member !! Lithologies !! Maximum thickness !! Notes
|-
| rowspan=21 style="background-color: {{period color|ypresian}};" | [[Ypresian]] || align=center | C22n || rowspan=2 | [[Zenne Group|Zenne]] || rowspan=2 | [[Aalter Formation|Aalter]] || Oedelem Sand || [[Sandstone]] || rowspan=2 | || rowspan=2 align=center | <ref name=FWAalter>[https://paleobiodb.org/classic/displayStrata?geological_group=&formation=Aalter&group_formation_member=Aalter Aalter Formation] at [[Fossilworks]].org</ref>
|-
| rowspan=7 align=center | C22r || Beernem Sand || Sandstone
|-
| rowspan=16 | '''Ieper''' || rowspan=5 | [[Gentbrugge Formation|Gentbrugge]] || Aalterbrugge Lignite || [[Lignite]] || rowspan=5 | {{convert|50|m|ft|abbr=on}} || rowspan=5 align=center | <ref name=NSCBGentbrugge>[https://ncs.naturalsciences.be/paleogene-neogene/275-gentbrugge-formation-012017 Gentbrugge Formation]</ref>
|-
| Vierzele Sand || Sandstone
|-
| Pittem Clay || [[Claystone]]
|-
| Merelbeke Clay || Claystone
|-
| Kwatrecht Complex
|-
| [[Mons-en-Pévèle Formation|Mons-en-Pévèle]] || || [[Micaceous]] sandstone || A few meters || align=center | <ref name=NSCBMons>[https://ncs.naturalsciences.be/paleogene-neogene/272-mons-en-p%c3%a9v%c3%a8le-formation Mons-en-Pévèle Formation]</ref>
|-
| rowspan=5 align=center | C23n || rowspan=3 | [[Hyon Formation|Hyon]] || Mont-Panisel || Sandstone || rowspan=3 | {{convert|25|m|ft|abbr=on}} || rowspan=3 align=center | <ref name=NCSBHyon>[https://ncs.naturalsciences.be/paleogene-neogene/274-hyon-formation-012017 Hyon Formation] - National Commission on the Stratigraphy of Belgium</ref>
|-
| Bois-la-Haut Sand || Sandstone
|-
| Egem || Claystone
|-
| rowspan=2 | [[Tielt Formation|Tielt]] || Egemkapel || Sandstone || rowspan=2 | {{convert|25|m|ft|abbr=on}} || rowspan=2 align=center | <ref name=NCSBTielt>[https://ncs.naturalsciences.be/paleogene-neogene/273-tielt-formation-012017 Tielt Formation] - National Commission on the Stratigraphy of Belgium</ref>
|-
| Kortemark || [[Siltstone]]
|-
| align=center | C23r || rowspan=5 | [[Kortrijk Formation|Kortrijk]] || Aalbeke || Claystone || rowspan=5 | {{convert|125|m|ft|abbr=on}} || rowspan=5 align=center | <ref name=NCSBKortrijk>[https://ncs.naturalsciences.be/paleogene-neogene/271-kortrijk-formation-012017 Kortrijk Formation] - National Commission on the Stratigraphy of Belgium</ref>
|-
| align=center | C24n || Roubaix || Claystone
|-
| rowspan=6 align=center | C24r || Orchies
|-
| Mt. Héribou || Claystone
|-
| Het Zoute || Siltstone
|-
| rowspan=3 | [[Landen Group|Landen]] || rowspan=3 | [[Tienen Formation|Tienen]] || Oosthoek Sand || Sandstone || rowspan=3 | || rowspan=3 align=center | <ref name=FWTienen>[https://paleobiodb.org/classic/displayStrata?geological_group=&formation=Tienen&group_formation_member=Tienen Tienen Formation] at [[Fossilworks]].org</ref>
|-
| Knokke Clay || Claystone
|-
| Dormaal Sand || Sandstone
|-
|}

=== Outcrops ===
The [[Kortrijk Formation]] predominantly consists of marine [[clay]]. It occurs in the west and north of Belgium, the [[Tielt Formation]], consisting of fine [[sand]], is found in the subsurface of western and central Belgium and the [[Gentbrugge Formation]], which comprises an alternation of clay, [[silt]] and fine sand, [[outcrop|crops out]] in [[East Flanders|East]] and West Flanders.

The Ieper Group lies stratigraphically on top of the [[Landen Group]] (upper [[Paleocene]]) and below the [[Zenne Group]] (like the Ieper Group early Eocene in age). Unlike the Zenne Group, the Ieper Group can also occur in more southern parts of Belgium, for example in the [[Mons Basin]].

== Paleontology ==
The Tielt Formation has provided fossils of [[mammal]]s, [[bird]]s and [[reptiles]].<ref name=Smith2003>Smith & Smith, 2003</ref>

== See also ==
* [[List of fossiliferous stratigraphic units in Belgium]]
* [[:Category:Ypresian Stage|Ypresian formations]]
** [[Fur Formation]] of Denmark
** [[London Clay Formation]] of England
** [[Silveirinha Formation]] of Portugal
* [[:Category:Wasatchian|Wasatchian formations]]
** [[Nanjemoy Formation]] of the eastern United States
** [[Wasatch Formation]] of the western United States
* [[:Category:Itaboraian|Itaboraian formations]]
** [[Itaboraí Formation]] of Brazil
** [[Laguna del Hunco Formation]] of Argentina

== References ==
{{reflist|2}}

=== Bibliography ===

* {{citation |last1=Steurbaut |first1=Etienne |first2=Marleen |last2=De Ceukelaire |first3=Tim |last3=Lanckacker |first4=Johan |last4=Matthijs |first5=Peter |last5=Stassen |first6=Hervé |last6=Van Baelen |first7=Noël |last7=Vandenberghe |year=2017 |title=An update of the lithostratigraphy of the Ieper Group |url=https://ncs.naturalsciences.be/sites/default/files/Litho%20Ieper%20Group%20201702.pdf |publisher=[[National Commission for the Stratigraphy of Belgium]] |pages=1–79 |accessdate=2020-09-07}}
* {{citation |last=Steurbaut |first=Etienne |year=2006 |title=Ypresian |url=https://popups.uliege.be/1374-8505/index.php?id=1101 |journal=[[Geologica Belgica]] |volume=9 |pages=73–93 |accessdate=2020-09-07}}
* {{citation |last1=Smith |first1=T. |first2=R. |last2=Smith |year=2003 |title=Terrestrial mammals as biostratigraphic indicators in upper Paleocene-lower Eocene marine deposits of the southern North Sea Basin |journal=Geological Society of America Special Paper |volume=369 |pages=513–520}}
* {{citation |last1=Laga |first1=P. |last2=Louwye |first2=S. |last3=Geets |first3=S. |year=2001 |title=Paleogene and Neogene lithostratigraphic units (Belgium) |url=https://popups.uliege.be/1374-8505/index.php?id=1954 |journal=[[Geologica Belgica]] |volume=4 |issue=1–2 |pages=135–152 |doi=10.20341/gb.2014.050 |accessdate=2020-09-07|doi-access=free }}
* {{citation |last=Willems |first=W |year=1974 |title=An aberrant ''Uvigerina'' from the Lower Eocene of Belgium |journal=[[Micropaleontology (journal)|Micropaleontology]] |volume=20 |issue=4 |pages=478–479|doi=10.2307/1485134 |jstor=1485134 |bibcode=1974MiPal..20..478W }}

;Other Ypresian
* {{citation |last1=Guerrera |first1=F. |first2=M.A. |last2=Mancheño |first3=M. |last3=Martín Martín |first4=G. |last4=Raffaelli |first5=T. |last5=Rodríguez Estrella |first6=F. |last6=Serrano |year=2014 |title=Paleogene evolution of the External Betic Zone and geodynamic implications |url=https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2014.12.3.1 |journal=[[Geologica Acta]] |volume=12 |pages=171–192 |accessdate=2020-09-07}}
* {{citation |last1=Molina |first1=Eustoquio |first2=Concepción |last2=Gonzalvo |first3=Miguel A. |last3=Mancheño |first4=Silvia |last4=Ortiz |first5=Birger |last5=Schmitz |first6=Ellen |last6=Thomas |first7=Katharina |last7=von Salis |year=2006 |title=Integrated stratigraphy and chronostratigraphy across the Ypresian-Lutetian transition in the Fortuna Section (Betic Cordillera, Spain) |url=https://www.researchgate.net/publication/233648662 |journal=[[Newsletters on Stratigraphy]] |volume=42 |pages=1–19 |doi=10.1127/0078-0421/2006/0042-0001 |accessdate=2020-09-07}}
* {{citation |last1=Larrasoaña |first1=J.C. |last2=Gonzalvo |first2=C. |last3=Molina |first3=E. |last4=Monechi |first4=S. |last5=Ortiz |first5=S. |last6=Tori |first6=F. |last7=Tosquella |first7=J. |year=2008 |title=Integrated magnetobiochronology of the Early/Middle Eocene transition at Agost (Spain): Implications for defining the Ypresian/Lutetian boundary stratotype |url=http://wzar.unizar.es/perso/emolina/pdf/Larrasoana2008Lethaia.pdf |journal=[[Lethaia]] |volume=41 |issue=4 |pages=395–415 |doi=10.1111/j.1502-3931.2008.00096.x |bibcode=2008Letha..41..395L |hdl=2158/253940 |accessdate=2020-09-07}}
* {{citation |last1=Dupuis |first1=Christian |first2=Marie-Pierre |last2=Aubry |first3=Etienne |last3=Steurbaut |first4=William A. |last4=Berggren |first5=Khaled |last5=Ouda |first6=Roberto |last6=Magioncalda |first7=Benjamin S. |last7=Cramer |first8=Dennis V. |last8=Kent |first9=Robert P. |last9=Speijer and Claus Heilmann-Clausen |year=2003 |title=The Dababiya Quarry Section: Lithostratigraphy, clay mineralogy, geochemistry and paleontology |url=https://www.researchgate.net/publication/236605087 |journal=[[Micropalaeontology (journal)|Micropalaeontology]] |volume=49 |pages=41–59 |doi=10.2113/49.Suppl_1.41 |bibcode=2003MiPal..49S..41D |accessdate=2020-09-07}}

[[Category:Geologic groups of Europe]]
[[Category:Lithostratigraphy of Belgium]]
[[Category:Eocene Series of Europe]]
[[Category:Paleogene Belgium]]
[[Category:Ypresian Stage| ]]
[[Category:Antwerp Province|Formations]]
[[Category:East Flanders|Formations]]
[[Category:West Flanders|Formations]]
[[Category:Hainaut (province)|Formations]]
[[Category:Flemish Brabant|Formations]]
[[Category:Walloon Brabant|Formations]]

Ieper Group - Revision history

imported>Volcanoguy: removed Category:Geography of Antwerp Province; added Category:Antwerp Province using HotCat