The BGS Lexicon of Named Rock Units — Result Details

Heron Group

Computer Code: HERO Preferred Map Code: notEntered
Status Code: Full
Age range: Lopingian Epoch (PUL) — Hettangian Age (JH)
Lithological Description: The Heron Group is composed largely of continental clastic sediments that were deposited in rapidly subsiding Triassic intracratonic basins of the Central and Northern North Sea. Sedimentation patterns were strongly influenced by contemporary halokinesis of underlying Permian salts in parts of the Central North Sea, and by movements on marginal and intrabasinal faults in the Moray Firth, South Viking Graben and East Shetland Basin.
Definition of Lower Boundary: The Heron Group rests on Upper Permian evaporites, carbonates and clastic sediments of the Zechstein Group, and locally extends beyond these to rest on pre-Permian strata or on metamorphic basement.
Definition of Upper Boundary: The Heron Group is unconformably overlain by Middle Jurassic or younger strata across most of the Central and Northern North Sea (Lervik et al., 1989, fig.3), but is conformably overlain by the (early Jurassic) Dunrobin Bay Group in the western Inner Moray Firth and by the Banks Group in parts of the Beryl Embayment and in the Brent-Statfjord area (Richards et al., 1993). In these areas, the group is believed to extend into the early Hettangian, but, in the absence of any distinctive lithological marker, the Triassic/Jurassic boundary can for practical purposes be taken at the top of the dominantly red sediments of the Heron Group.
Thickness: Up to 1745 m of Triassic sediments have been proved by drilling in the East Shetland Basin, and they may be locally more than 2000 m thick elsewhere.
Geographical Limits: Central and Northern North Sea.
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):
Ritchie, J D, Gatliff, R W and Riding, J, 1996. 1. Pre - Tertiary lithostratigraphy. In: Stratigraphic Nomenclature of the UK North West Margin. British Geological Survey, Nottingham. 
Cameron, T D J. 1993. 4. Triassic, Permian and pre-Permian 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. 
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. 
Vollset, J and Doré, A G. 1984. A revised Jurassic and Triassic lithostratigraphic nomenclature for the Norwegian North Sea. NPD-Bulletin No.3. 
Lervik, K S, Spencer, A M, and Warrington, G. 1989. Outline of Triassic stratigraphy and structure in the central and northern North Sea. In: Collinson, J D (ed.) Correlation in hydrocarbon exploration, 173-189. Graham and Trotman, London. 
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.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S095