| Computer Code: |
SKAD |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Oligocene Epoch (GO)
— Miocene Epoch (NM) |
| Lithological Description: |
The Skade Formation consists of fine to coarse grained, often shelly sandstone with subordinate beds of brown silty mudstones or siltstone. |
| Definition of Lower Boundary: |
In distal sections, the base of the Skade Formation is marked by a downward transition from sandstone to brown-grey or grey-brown mudstone of the Lark Formation. In more proximal sections, in which the Lark Formation is absent, the base of the Skade Formation is marked by a downward change from highly glauconitic silty mudstone to sandstone of the Mousa Formation. Normal wireline log responses are displayed in both cases, except that a high-gamma peak is commonly present at the base of the Skade Formation in proximal sections, reflecting the high glauconite content. The sandstone unit at the top of the underlying Mousa Formation is also glauconite-rich, but displays distinctly lower gamma-ray values e.g. 14/19-8 and 15/21-1). |
| Definition of Upper Boundary: |
The top of the Skade Formation is typically marked by a downward change from green-grey, glauconitic, silty mudstone (Nordland Group) to shelly sandstone. The boundary is marked by a downhole decrease in gamma values, with a distinct high-gamma peak often occurring in the basal sediments of the Nordland Group. Where sandstone is present at the base of the overlying Nordland Group (Utsira Formation), the boundary may be difficult or impossible to define (but refer to the Nordland Group for comments concerning the status of the Utsira Formation). |
| Thickness: |
Rarely exceeds 200 m in thickness. |
| Geographical Limits: |
The Skade Formation extends over western marginal areas of the Central and Northern North Sea. Lott and Knox (1994) extended the geographical range of the Skade Formation into the Southern North Sea area. |
| Parent Unit: |
Westray Group (WESY)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
North Sea well 9/28- 5: 499.5-1049 m (1638-3441 ft). Knox and Holloway (1992). Note: type section N24/2-1 (Isaksen and Tonstad 1989, p.52, fig.61): 851-1007 m (2792-3304 ft) below KB. This well has not been located. |
| 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.) |
| 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. |
| Isaksen, D and Tonstad, K. 1989. A revised Cretaceous and Tertiary lithostratigraphic nomenclature for the Norwegian North Sea. NPD-Bulletin No.5 |
| 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. |
| Knox, R W O'B and Holloway, S. 1992. 1. Paleogene 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
