Ypresian

First age of the Eocene Epoch From Wikipedia, the free encyclopedia

In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between 56 and 48.07 Ma, is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian is consistent with the Lower Eocene (Early Eocene).

Formerly part ofTertiary Period/System
Name formalityFormal
Celestial bodyEarth
Regional usageGlobal (ICS)
Quick facts Chronology, Formerly part of ...
Ypresian
56.00 – 48.07 Ma
Earth ~50 mya
Klondike Mountain Formation, Republic, Washington
Chronology
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MZ
 
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First Antarctic permanent ice-sheets[1]
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Subdivision of the Paleogene according to the ICS, as of 2024.[2]
Vertical axis scale: Millions of years ago
Formerly part ofTertiary Period/System
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
First proposed byDumont
Time span formalityFormal
Lower boundary definitionStrong negative anomaly in δ13C values at the PETM[3]
Lower boundary GSSPDababiya section, Luxor, Egypt[3]
25.5000°N 32.5311°E / 25.5000; 32.5311
Lower GSSP ratified2003[3]
Upper boundary definitionFAD of the calcareous nannofossil Blackites inflatus
Upper boundary GSSPGorrondatxe section, Western Pyrenees, Basque Country, Spain
43.3796°N 3.0143°W / 43.3796; -3.0143
Upper GSSP ratifiedApril 2011[4]
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Palaeoclimatology

See also: Cambay Shale Formation, pCO2, and δ18O

The Ypresian Age begins during the throes of the Paleocene–Eocene Thermal Maximum (PETM). The Fur Formation in Denmark, the Messel shales in Germany, the Oise amber of France and Cambay amber of India are of this age. The Eocene Okanagan Highlands are an uplands subtropical to temperate series of lakes from the Ypresian.[5][6][7]

The Ypresian is additionally marked by another warming event called the Early Eocene Climatic Optimum (EECO). The EECO is the longest sustained warming event in the Cenozoic record, lasting about 2–3 million years between 53 and 50 Ma. The interval is characterized by low oxygen-18 isotopes,[8][9][10] high levels of atmospheric pCO2,[11][12] and low meridional thermal gradients.[13] Biodiversity has been reported to have been significantly impacted by the conditions prevalent during the EECO. For instance, there were biotic turnovers among marine producers such as calcareous nannofossils among others etc.[14][15]

Southern China was incredibly arid during the Ypresian, owing to a strong subtropical anticyclone engendered by extremely warm temperatures and a rain–shadow effect resulting from coastal mountains.[16]

Stratigraphic definition

See also: List of geochronologic names

The Ypresian Stage was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1850. The Ypresian is named after the Flemish city of Ypres in Belgium (spelled Ieper in Dutch). The definitions of the original stage were totally different from the modern ones.[17] The Ypresian shares its name with the Belgian Ieper Group (French: Groupe d'Ypres), which has an Ypresian age.

The base of the Ypresian Stage is defined at a strong negative anomaly in δ13C values at the PETM. The official reference profile (GSSP) for the base of the Ypresian is the Dababiya profile near the Egyptian city of Luxor.[18] Its original type section was located in the vicinity of Ieper.

The top of the Ypresian (the base of the Lutetian) is identified by the first appearance of the foraminifera genus Hantkenina in the fossil record.

The Ypresian Stage overlaps the upper Neustrian and most of the Grauvian European Land Mammal Mega Zones (it spans the Mammal Paleogene zones 7 through 10.[19]), the Wasatchian and lower and middle Bridgerian North American Land Mammal Ages, the Casamayoran South American Land Mammal Age and the Bumbanian and most of the Arshantan Asian Land Mammal Ages. It is also coeval with the upper Wangerripian and lowest Johannian regional stages of Australia and the Bulitian, Penutian, and Ulatisian regional stages of California.

Notable geological formations

Being a period of high sea levels, numerous geological formations worldwide were deposited during the Ypresian stage in both inland and marine habitats. The following fossiliferous geological formations are among those known from this time:[20]

North America
South America
Antarctica
Europe
Asia
Africa
  • Esna, El Rufuf Formation and Thebes Formations, Egypt
  • Al Jir and Jdeir Formations, Libya
  • Gafsa Phosphates Formation, Tunisia
  • Ait Ouarhitane Formation, Morocco
  • Tamaguélelt Formation, Mali
  • Thies Formation, Senegal
  • Auradu Formation, Somalia
  • Landana Formation, Cabinda, Angola
Oceania
  • Red Bluff Tuff Formation, Tutuiri Greensand and Tumaio and Te Whanga Limestones, New Zealand
  • Macquarie Harbor Formation, Tasmania, Australia
  • Dilwyn Formation, Victoria
  • Redbank Plains Formation, Queensland
  • Jubilee Member of Cardabia Formation, Western Australia

References

External links

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