| Computer Code: |
CRUI |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Albian Age (KA)
— Albian Age (KA) |
| Lithological Description: |
The Cruiser Formation consists predominantly of mid grey to dark grey mudstones. These may be carbonaceous (with plant fragments), micaceous, pyritic, and interbedded with occasional thin siltstones, fine quartz sandstones and limestones. Much of the mudstone is non-calcareous. Within the Cruiser Formation in 205/10-2B, there are numerous Tertiary or older intrusions. |
| Definition of Lower Boundary: |
In the centre of the Faeroe-Shetland Basin, the base of the Cruiser Formation has not been reached and the lower boundary cannot yet be defined in this area. Along the margins of the basin or on intrabasin highs, the Cruiser Formation either rests unconformably on older strata (e.g. Kimmeridge Clay Formation in 206/5-1) or on the sandstones and conglomerates of the Royal Sovereign Formation. |
| Definition of Upper Boundary: |
The top of the Cruiser Formation is normally defined by a downward change from the interbedded limestones, siltstones and mudstones of the Svarte Formation into more uniform mudstones. It is usually marked on wireline logs by a downward change from the more irregular and generally higher gammaray and sonic velocities associated with the Svarte Formation. |
| Thickness: |
It is 772 m thick in the type well. It reaches a maximum drilled thickness of 1154.5 m in 214/29-1Z, although there are no wireline logs covering the basal 423 m in this well, and the base of the formation was not reached. |
| Geographical Limits: |
The Cruiser Formation is restricted to the Faeroe-Shetland Basin. |
| Parent Unit: |
Cromer Knoll Group (CRKN)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 206/03- 1: 3770.5-4542.5 m (12370-14903 ft) (Ritchie et al., 1996). |
| 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.) |
| 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
