The BGS Lexicon of Named Rock Units — Result Details

Herring Formation

Computer Code: HERN Preferred Map Code: notEntered
Status Code: Full
Age range: Turonian Age (KT) — Turonian Age (KT)
Lithological Description: The Herring Formation consists of hard to very hard, dense, cryptocrystalline limestone with interbedded argillaceous chalky limestone and mudstone. Traces of pyrite, glauconite and chert have been reported. The limestones are white to pale grey, occasionally medium grey and buff. The mudstones are sub-fissile, carbonaceous, non-calcareous to calcareous, hard to soft, and finely laminated in part. They are dark grey to black and locally red-brown or varicoloured. In the South Viking Graben, thin, glauconitic, quartzose sandstones are present in the lower part of the Herring Formation (e.g. 16/28-7).
Definition of Lower Boundary: The base of the Herring Formation is normally marked by a sharp downward change from black mudstones (Black Band) to chalky limestones of the Hidra Formation. It is marked on wireline logs by a sharp downward decrease in gamma-ray values and an increase in velocity. Where the Black Band is absent, limestones of the Herring Formation disconformably overlie the Hidra Formation (e.g. 21/1-7ST, see fig.5 in Burnhill and Ramsay, 1981, and 14/26-1). On intrabasinal highs, the Herring Formation locally rests unconformably on the Lower Cretaceous or older rocks (e.g. 14/13-1; 16/28-4 on Carrack Formation; 16/23-4 on Kimmeridge Clay Formation).
Definition of Upper Boundary: The top of the Herring Formation is normally marked by a downward change from argillaceous chalky limestones of the Mackerel Formation or calcareous mudstones of the Flounder Formation to cleaner, denser, high-velocity chalky limestone. It is marked on wireline logs by a downward decrease in gamma values and an increase in velocity. Commonly, the basal parts of the overlying Mackerel and Flounder formations display a downward decrease in gamma values and an increase in volocity (e.g. 16/28-7 and 15/28a-3). In the South Viking Graben, the Herring Formation is locally overlain by the Kyrre Formation (e.g. 16/3-1).
Thickness: The formation generally ranges from 25 to 75 m, but locally reaches over 120 m (e.g. 22/3a-1). Lower units of the Herring Formation are eroded and overlapped over local structural highs (see fig.5 in Burnhill and Ramsay, 1981).
Geographical Limits: The Herring Formation can be recognized throughout the Central North Sea and extends into the South Viking Graben. It is absent, however, over some contemporary structural highs. Whilst seismic data suggest onlap onto these structures (Gatliff et al., 1994), condensed sections are also present, and the absence of the Herring Formation may indicate intra-Cretaceous erosion.
Parent Unit: Chalk Group (CK)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  North Sea well 22/01- 2A (Deegan and Scull, 1977): 3605-3738.5 m (11827-12265 ft) below KB (revised depths). 
Reference Section  North Sea well 13/28- 2: 1405.5-1468.5 m (4611-4818 ft) (Johnson and Lott, 1993). 
Reference Section  North Sea well 16/12b- 10: 3679.5-3792.5 m (12072-12442 ft) (Johnson and Lott, 1993). 
Reference Section  North Sea well 29/5a- 1: 3878-4056 m (12723-13306 ft) (Johnson and Lott, 1993). 
Reference(s):
Johnson, H and Lott, G K. 1993. 2. Cretaceous 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. 
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. 
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.) 
Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. 
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. 
Gatliff, R W, Richards, P C, Smith, K, Graham, C C, McCormac, M, Smith, N J P, Long, D, Cameron, T D J, Evans, D, Stevenson, A G, Bulat, J, and Ritchie, J D. 1994. United Kingdom offshore regional report: the geology of the central North Sea. (London: HMSO for the British Geological Survey.) 
Burnhill, T J, and Ramsay, W V. 1981. Mid-Cretaceous palaeontology and stratigraphy, Central North Sea. In: Illing, L V, and Hobson, G D (eds) Petroleum geology of the continental shelf of North-West Europe, 245-254. Heyden and Son, London. 
Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern 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