The BGS Lexicon of Named Rock Units — Result Details

Statfjord Formation

Computer Code: STAT Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Rhaetian Age (TR) — Sinemurian Age (JS)
Lithological Description: The formation comprises interbedded sandstones, siltstones, mudstones and occasional minor coals. In the East Shetland Basin, sandstones are pale grey to white, fine- to very coarse-grained, sometimes pebbly, micaceous, variably kaolinitic and sometimes cross-bedded. Siltstones and mudstones are grey, green, reddish-brown, occasionally red, micaceous and sometimes carbonaceous. Coal seams up to 3.5 m thick occur locally. In the Beryl Embayment sandstone beds usually have sharp bases and frequently form upward fining cycles. Cross-bedding and ripple-lamination are present. Carbonized wood is present. Thin sandstones, which are interbedded with siltstones, mudstones and coal, show parallel to sub-parallel laminations, ripple laminations and water escape structures. The associated mudstones are mid-grey, generally blocky and massive (but occasionally fissile).
Definition of Lower Boundary: The lower boundary is defined by a downward change from mainly pale grey, white and green coloured, mainly arenaceous deposits to predominantly red argillaceous facies (Cormorant Formation). A down-section increase in gamma values may occur.
Definition of Upper Boundary: Defined by a downward change from sandstones (Nansen Formation) to interbedded sandstones, mudstones and minor coals, associated with a down-section increase in gamma values and a more erratic gamma-ray log response.
Thickness: East Shetland Basin: up to more than 300 m. Beryl Embayment: up to c. 80 m.
Geographical Limits: East Shetland Basin, Beryl Embayment and Viking Graben. North Sea quadrants 3, 9 and 211.
Parent Unit: Banks Group (BAKS)
Previous Name(s): Eriksson Formation (-5203)
Lower Beryl Sandstone 1 (-5205)
Lower Formation (-5206)
Nansen Member (-5195)
Raude Member (-5207)
Scott Formation (-5208)
Statfjord Sand Formation (-5209)
Eriksson Member (-5204)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  North Sea Well N33/12-2 between 2719 and 2951 m below KB (Deegan and Scull, 1977; revised by Richards et al., 1993). 
Reference Section  North Sea Well 211/24-1 between 3158.5 and 3434 m (Richards et al., 1993). 
Reference Section  North Sea Well 3/15-2 between 3645.5 and 3997 m (Richards et al., 1993). 
Reference Section  North Sea Well 9/13-19 between 3842 and 3910.5 m (Richards et al., 1993). 
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. 
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] 
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. 1991. The evolution of Lower Jurassic coastal plain and fan delta sediments in the Beryl Embayment, North Sea. Journal of the Geological Society, London, 148, 1037-1047. 
Richards, P C. 1989. Lower and Middle Jurassic sedimentology of the Beryl Embayment, and implications for the evolution of the northern North Sea. Unpublished Ph.D. thesis, University of Strathclyde. 
Richards, P C. 1990. The early to mid-Jurassic evolution of the northern North Sea. In: Hardman, R F P and Brooks, J (eds.) Tectonic events responsible for Britain's oil and gas reserves. Special Publication of the Geological Society, London, No.55, 191-205. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable