The BGS Lexicon of Named Rock Units — Result Details

Fladen Group

Computer Code: FLDN Preferred Map Code: notEntered
Status Code: Full
Age range: Aalenian Age (JA) — Oxfordian Age (JO)
Lithological Description: Sandstones, mudstones and coals of the defining formations (listed here in alphabetical order): Beatrice Formation (including the Carr and Louise members); Brora Coal Formation; Hugin Formation; Pentland Formation (including the Rattray Volcanics, Ron Volcanics and Stroma members).
Definition of Lower Boundary: The lower group boundary is defined by the base of the Pentland Formation, which unconformably overlies Permian, Triassic and Lower Jurassic sediments. Where it overlies Permian sediments, the base is marked by a downward change from coal-bearing sediments and/or volcanics to evaporite-bearing sediments; where it overlies the Triassic, the boundary is marked by a transition from grey coal-bearing sediments and/or volcanics to brick-red siltstones and sandstones; where it overlies Lower Jurassic strata, the boundary is marked by a downward transition from interbedded sandstones, siltstones and coals to predominantly grey siltstones with minor sandstones.
Definition of Upper Boundary: The upper group boundary is variable in the northern North Sea, but is normally marked by the upward transition from sandstones or interbedded sandstones, siltstone and coal to mudstones and siltstones of the overlying Heather Formation (Humber Group). The top of the Fladen Group is generally the top of the Hugin Formation, but in the Central Graben, either the Pentland Formation or Beatrice formation underlies the Heather Formation.
Thickness: none recorded or not applicable
Geographical Limits: Northern North Sea: Unst Basin, Shetland Basin, Beryl Embayment, Viking Graben, Central Graben, Moray Firth.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) 
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. 
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 (eds.). 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