| Computer Code: |
OCKS |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Danian Age (GD)
— Danian Age (GD) |
| Lithological Description: |
The Ockran Sandstone Formation consists of medium to coarse grained, variably argillaceous, bioclastic sandstone grading to sandy limestone towards the base. The bioclastic debris includes bivalves, gastropods and, most distinctively, bryozoans. Wireline-log character indicates that the formation is consistently sandy and well bedded. Calcite-cemented beds are represented by high-velocity spikes, these are especially abundant in the lower part of the 205/26a-2 section, in which the calcareous sandstone grades into sandy limestone. |
| Definition of Lower Boundary: |
The base of the Ockran Sandstone Formation is defined by a downward change from bioclastic sandstone or sandy bioclastic limestone to calcareous mudstone. It is marked by a sharp downward increase in gamma-ray values and decrease in velocity. |
| Definition of Upper Boundary: |
The top of the Ockran Sandstone Formation is defined by a sharp downward change from calcareous mudstone to sandstone, and by an accompanying downward decrease in gamma-ray values. |
| Thickness: |
It reaches a maximum recorded thickness of 260 m in well 205/26a-2. |
| Geographical Limits: |
UK north west margin. The Ockran Sandstone Formation is restricted to a small area in the southwestern basin margin. |
| Parent Unit: |
Shetland Group (STLN)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 205/26a- 2: 579-840 m (1900-2756 ft) (Knox et al., 1997). |
| Type Section |
North Sea well 205/26a- 2: 579-840 m (1900-2756 ft) (Knox et al., 1997). |
| Reference Section |
North Sea well 204/30- 1: 707-789.5 m (2320-2590 ft) (Knox et al., 1997). |
| Reference(s): |
| Knox, R W O'B, Holloway, S, Kirby, G A and Baily, H E. 1997. Stratigraphic nomenclature of the UK North West Margin. 2. Early Paleogene lithostratigraphy and sequence stratigraphy. British Geological Survey, Nottingham. |
| Hitchen, K, and Ritchie, J D. 1987. Geological Review of the West Shetland area. In: Brooks, J, and Glennie, K W (eds.) Petroleum geology of North West Europe. (London: Graham and Trotman), 737-749. |
| 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.) |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
