The BGS Lexicon of Named Rock Units — Result Details

Dunlin Group

Computer Code: DUNL Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Hettangian Age (JH) — Aalenian Age (JA)
Lithological Description: Siltstones and mudstones, sometimes sandy, together with minor quantities of sandstone. The group is defined as containing the following formations: Amundsen Formation Burton Formation Cook Formation Darwin Formation Drake Formation Speke Formation
Definition of Lower Boundary: The lower boundary is placed at the base of the Amundsen Formation, which is placed at a downward change from mudstones to sandstones (Nansen Formation) and a downward decrease in gamma values.
Definition of Upper Boundary: The upper boundary is defined by the top of the Drake Formation. This is placed at a downward change from sandstones (Broom Formation) to mudstones and a downward increase in gamma values. Locally there is a downward change from micaceous mudstones (of the Rannoch Formation) to poorly micaceous mudstones accompanied by a decrease in gamma values and increase in velocity.
Thickness: North Viking Graben: up to c. 1000 m. East Shetland Basin: a few metres to +250 m.
Geographical Limits: East Shetland Basin to Viking Graben and Beryl Embayment plus Unst Basin. UK North Sea quadrants 1, 2, 3, 9, 210, 211.
Parent Unit: Not Applicable (-)
Previous Name(s): Dunlin Shale Unit (-5188)
Dunlin Silt Unit (-5189)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Deegan, C E and Scull, B J. 1977. A standard lithostratigraphic nomenclature for the Central and Northern North Sea. Report of the Institute of Geological Sciences, 77/25; NPD Bulletin No.1. 
Bowen, J M. 1975. The Brent Oil-Field. In: Woodland, A W (ed.) Petroleum and the contineental shelf of North-West Europe, 353-361. [Heyden & Son, London] 
Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic of the Central and Northern North Sea. In: Knox, R W O'B and Cordey, W G. Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable