updated to follow: Stratigraphic Guide to the Cromer Knoll, Shetland and Chalk Groups of the North Sea and Norwegian Sea. Felix M. Gradstein & Colin C. Waters (editors), Mike Charnock, Dirk Munsterman, Michelle Hollerbach, Harald Brunstad, Øyvind Hammer & Luis Vergara (contributors). Newsletter on Stratigraphy, vol 49/1 pp71-280, 2016
Cromer Knoll Group
The term Britannia Sandstone Formation was introduced by Johnson & Lott (1993). The formation was formerly known as the Kopervik Formation (informal in oil company reports; Bisewski, 1990; Guy, 1992), the Bosun Sands (informal oil company reports; Andrews et al., 1990) and Bosun Sand Member, Sola Formation (Crittenden et al., 1991).
Up to 180m in the Fisher Bank Basin (Johnson & Lott, 1993).
The formation occurs in the southeast of the Outer Moray Firth, extending westwards into the Glenn Horst, and is most thickly developed in the Fisher Bank Basin (Quadrants 15-16, 21-22) of Central North Sea. The formation onlaps the Fladen Ground Spur, which is believed to have been a source area for the sands, along with the Glenn Horst and Jaeren High (Johnson & Lott, 1993).
|Central North Sea (Johnson & Lott, 1993)|
16/26-16: 3995-4195.5 m (13106-13764ft)
|Lat. 58° 02’18.42”N
Lat. 57° 58’ 07.184”N
Lat. 57° 58’50.05”N
|Long. 01° 07’ 06.45”E
Long. 00°12’ 29.786”E
Long. 01° 29’ 21.68”E
The upper boundary is normally defined by the downward change from mudstones (Carrack Formation) to sandstones (Britannia Sandstone Formation). Locally the Britannia Sandstone Formation is overlain by the Valhall Formation (e.g.22/1a-3, Johnson & Lott, 1993)
The formation generally yields abundant palynofloras. The Cerbia tabulata biomarker occurs in the upper part of the formation, whereas Ctenidodinium elegantulum, Heslertonia heslertonensis, Hystrichodinium ramoides, Batioladinium longicornutum and Pseudoceratium anaphrissum biomarkers occur in the lower part. A diverse fauna of agglutinated foraminifera are present at the top of the formation, where the Verneuilinoides chapmani biomarker is recognized (Johnson & Lott, 1993).
The formation passes laterally into the argillaceous Carrack and Valhall formations.
The formation consists largely of marine mass-flow sandstones and interbedded marine mudstones. The presence of small amounts of skeletal debris and glauconite indicates the sands were derived from contemporaneous shallow shelf sands (Downie & Stedman, 1993). Guy (1992) interpreted much of the sandstone succession as representing high and low density turbidites, whereas Downie & Stedman (1993) postulated emplacement mainly as debris flows or liquefied deposits.
In the Kilda Field (Block 16/26), the formation has been divided into six informal sandstone facies (Guy, 1992), but Johnson & Lott (1993) informally subdivide the formation into two (Upper and Lower).