Braksøya Formation

Braksøya Formation
Stratigraphic range: Sheinwoodian ~428–426 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Formation
Overlies	Ringerike & Modum: Bruflat Formation Skien & Holmestrand: Porsgrunn & Skinnerbukta Formations
Lithology
Primary	Limestone
Location
Coordinates	60.0°N 10.2°E / 60.0; 10.2
Approximate paleocoordinates	21.1°S 8.1°W / -21.1; -8.1
Region	Buskerud
Country	Norway
Extent	Shallow Caledonian foreland basin
Type section
Named for	Braksøya naturreservat [no]
Braksøya Formation (Norway)

The Braksøya Formation is a geologic formation in the Ringerike and Modum areas in Buskerud, Norway, where it overlies the Bruflat Formation and the Skien and Holmestrand areas where it overlies the Porsgrunn Formation and Skinnerbukta Formation respectively.[1] The formation, deposited in a shallow Caledonian foreland basin at the edge of a closing Iapetus Ocean,[2] preserves fossils dating back to the Sheinwoodian stage of the Silurian period.[3]

Fossil content

Paleogeography of the Early Silurian with the closing Iapetus Ocean due to the Caledonian orogeny between Greenland and Norway

The stromatoporoid bioherms of the Braksøya Formation have provided fossils of:[3][4]

• Stromatoporida
  • Syringostromellidae
    • Syringostromella cf. aspectabilis
• Actinostromatida
  • Actinostromatidae
    • Plectostroma norvegicum
• Clathrodictyida
  • Clathrodictyidae
    • Clathrodictyon cf. crickmayi

See also

• List of fossiliferous stratigraphic units in Norway
• Buildwas Formation, Sheinwoodian type formation in England
• Llallagua Formation, Sheinwoodian fossiliferous formation in Bolivia

References

1. Worsley et al., 2011, p.102
2. Worsley et al., 2011, p.117
3. Braksøya Formation at Fossilworks.org
4. Nestor, 1999

Bibliography

• Worsley, D.; Baarli, B. G.; Howe, M. P. A.; Hjaltason, F.; Alm, D. (2011), "New data on the Bruflat Formation and the Llandovery/Wenlock transition in the Oslo Region, Norway", Norsk Geologisk Tidsskrift, 91: 101–120
• Nestor, H (1999), "Community structure and succession of Baltoscandian Early Palaeozoic stromatoporoids", Proceedings of the Estonian Academy of Sciences, 48: 123–139