| Computer Code: |
LKNB |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Callovian Age (JC)
— Callovian Age (JC) |
| Lithological Description: |
The formation comprises sandstones overlying thin mudstones with a thin, but persistent basal limestone bed. Sandstones are glauconitic and variably carbonate cemented. |
| Definition of Lower Boundary: |
The lower boundary is placed at the base of a thin limestone unit (coeval with the Cornbrash) where there is usually a downward change to mudstone dominated sediments (Hudleston Formation). It usually coincides with the base of a low gamma/high velocity spike. Locally, where the limestone is absent, the upper boundary is placed at a downward change from sandstone to variegated mudstone and a downward increase in gamma values and decrease in velocity. |
| Definition of Upper Boundary: |
The upper boundary is defined by a sharp down-section change from mudstones (Seeley Formation) or sandstones (Corallian Formation (Offshore)). A corresponding decrease in gamma values takes place at the boundary, and an increase in velocity. |
| Thickness: |
Up to 15 m. |
| Geographical Limits: |
Southern North Sea Basin, quadrants 42-43, 46-48, 51-52. |
| Parent Unit: |
West Sole Group (WSTS)
|
| Previous Name(s): |
West Sole Group
(WSTS)
|
| Alternative Name(s): |
Cornbrash Formation
|
| Stratotypes: |
| Type Section |
North Sea well 48/11b- 4 between 1007 and 1022 m (Lott and Knox, 1994). |
| Reference Section |
North Sea well 47/15a- 3 between 1134 and 1149 m (Lott and Knox, 1994). |
| Reference Section |
North Sea well 48/02- 1 between 603.5 and 621 m (Lott and Knox, 1994). |
| Reference Section |
North Sea well 47/14a- 2 between 1033 and 1047 m (Lott and Knox, 1994). |
| Reference(s): |
| 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. |
| 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
