| Computer Code: |
LISA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Callovian Age (JC)
— Callovian Age (JC) |
| Lithological Description: |
Medium- to coarse-grained (rarely fine-grained) sandstones, each bed being 1 to 10 m thick. Mudstone rip-up clasts, water escape features, and gravel lags present (Cockings et al., 1992). Relatively thin, dark grey to black mudstones are interbedded with the sandstones. |
| Definition of Lower Boundary: |
The base of the member is defined by a down-section change from sandstones to mudstones. It is marked by a sharp down-section increase in gamma-ray values and often a decrease in velocity. |
| Definition of Upper Boundary: |
The top is defined by a down-section transition from mudstone (Heather Formation) to sandstone; a down-section decrease in gamma ray values; and often by an increase in velocity. |
| Thickness: |
Up to 124 m. |
| Geographical Limits: |
Confined to North Sea Blocks 16/7 and 16/8, South Viking Graben. |
| Parent Unit: |
Heather Formation (HTHE)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 16/08a- 4 between depths 4757 and 4881 m (Cockings et al., 1992; Richards et al., 1993). |
| Reference(s): |
| Cockings, J H, Kessler, L G Ii, Mazza, T A, and Riley, L A. 1992. Bathonian to Mid-Oxfordian sequence stratigraphy of the south Viking Graben, North Sea. 65-105 in Exploration Britain: Geological insights for the next decade. Hardman, R F P (editor). Special Publication of the Geological Society, No. 67. |
| Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic 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 |
