Английская Википедия:Ieper Group
Шаблон:Short description Шаблон:Infobox rockunit The Ieper Group (Шаблон:Lang-nl; Шаблон:Lang-fr) is a group of rock strata in the subsurface of northwest Belgium. The group is subdivided into three marine formations, all formed during the Ypresian, a single age of the geologic timescale (55.8 to 48.6 million years ago, the oldest age of the Eocene epoch). Both age and group are named after the West Flemish town of Ypres, for which the Dutch name is "Ieper".
History of definition
Ypresian
Шаблон:Main Шаблон:See also 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 (Шаблон:Convert above mean sea level), surrounded from north to south by a series of low hills (between Шаблон:Convert). 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.[1]
A new stratotype for the Lutetian was proposed by Blondeau (1981) about Шаблон:Convert north of Paris. The neostratotype is located on the right bank of the river Oise at St. Leu d'Esserent and the large quarry at St. Vaast-les-Mello (Oise).[2]
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,[3] where the uppermost Tarawan Limestone, the Esna Formation and the lowermost Thebes Limestone define the Ypresian sequence.[4] Several other proposals for the lithostratigraphic redefinition of the top of the Ypresian exist;[5] among others the Punta Torcida Formation of the Austral or Magallanes Basin in Tierra del Fuego, the Azkorri Sandstone in the Gorrondatxe section of the North Pyrenean Foreland or Basque–Cantabrian Basin,[6][7] the Agost section close to Alicante in the Agost Basin in the Betic Cordillera,[8] and the Fortuna section north of Murcia in the Prebetic realm of the Betic Cordillera,[9][10] all in Spain. Other proposed type sections for the Ypresian-Lutetian boundary are located in France, Italy, Israel, Tunisia, Morocco, Cuba and Mexico.[5][11]
Stratigraphy
The Ieper Group was redefined by Steurbaut in 2006,[12] and is since 2017 subdivided into five formations by the National Commission for the Stratigraphy of Belgium, from youngest to oldest:[13]
Age | Chron | Group | Formation | Member | Lithologies | Maximum thickness | Notes |
---|---|---|---|---|---|---|---|
rowspan=21 style="background-color: Шаблон:Period color;" | Ypresian | C22n | Zenne | Aalter | Oedelem Sand | Sandstone | [14] | |
C22r | Beernem Sand | Sandstone | |||||
Ieper | Gentbrugge | Aalterbrugge Lignite | Lignite | Шаблон:Convert | [15] | ||
Vierzele Sand | Sandstone | ||||||
Pittem Clay | Claystone | ||||||
Merelbeke Clay | Claystone | ||||||
Kwatrecht Complex | |||||||
Mons-en-Pévèle | Micaceous sandstone | A few meters | [16] | ||||
C23n | Hyon | Mont-Panisel | Sandstone | Шаблон:Convert | [17] | ||
Bois-la-Haut Sand | Sandstone | ||||||
Egem | Claystone | ||||||
Tielt | Egemkapel | Sandstone | Шаблон:Convert | [18] | |||
Kortemark | Siltstone | ||||||
C23r | Kortrijk | Aalbeke | Claystone | Шаблон:Convert | [19] | ||
C24n | Roubaix | Claystone | |||||
C24r | Orchies | ||||||
Mt. Héribou | Claystone | ||||||
Het Zoute | Siltstone | ||||||
Landen | Tienen | Oosthoek Sand | Sandstone | [20] | |||
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, crops out in 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 mammals, birds and reptiles.[21]
See also
- List of fossiliferous stratigraphic units in Belgium
- Ypresian formations
- Fur Formation of Denmark
- London Clay Formation of England
- Silveirinha Formation of Portugal
- Wasatchian formations
- Nanjemoy Formation of the eastern United States
- Wasatch Formation of the western United States
- Itaboraian formations
- Itaboraí Formation of Brazil
- Laguna del Hunco Formation of Argentina
References
Bibliography
- Other Ypresian
- ↑ Steurbaut, 2006, p.74
- ↑ Molina et al., 2006, p.15
- ↑ Ypresian Stage at Encyclopedia Britannica
- ↑ Dupuis et al., 2003, p.44
- ↑ 5,0 5,1 Ypresian/Lutetian boundary stratotype - University of Zaragoza
- ↑ Bernaola et al., 2006, p.75
- ↑ Larrasoaña et al., 2008, p.396
- ↑ Larrasoaña et al., 2008, p.411
- ↑ Molina et al., 2006, p.8
- ↑ Guerrera et al., 2014, p.172
- ↑ Molina et al., 2006, p.2
- ↑ Steurbaut, 2006, p.76
- ↑ Ieper Group - National Commission for the Stratigraphy of Belgium
- ↑ Aalter Formation at Fossilworks.org
- ↑ Gentbrugge Formation
- ↑ Mons-en-Pévèle Formation
- ↑ Hyon Formation - National Commission on the Stratigraphy of Belgium
- ↑ Tielt Formation - National Commission on the Stratigraphy of Belgium
- ↑ Kortrijk Formation - National Commission on the Stratigraphy of Belgium
- ↑ Tienen Formation at Fossilworks.org
- ↑ Smith & Smith, 2003
- Английская Википедия
- Geologic groups of Europe
- Geologic formations of Belgium
- Lithostratigraphy of Belgium
- Eocene Series of Europe
- Paleogene Belgium
- Ypresian Stage
- Geography of Antwerp Province
- Geography of East Flanders
- Geography of West Flanders
- Geography of Hainaut (province)
- Geography of Flemish Brabant
- Geography of Walloon Brabant
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