| Computer Code: |
BCSA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Tithonian Age (JI)
— Berriasian Age (KR) |
| Lithological Description: |
Fine to medium-grained, moderately well sorted sandstones with sporadic, intercalated mudstones that attain a thickness of several metres. |
| Definition of Lower Boundary: |
A downward transition from sandstones to organic-rich mudstones (Kimmeridge Clay Formation, undifferentiated). The boundary is marked by a sharp increase in gamma-ray values and a decrease in velocity. |
| Definition of Upper Boundary: |
The upper boundary is normally placed at a downward change from mudstones or marls (Cromer Knoll Group) to sandstones. However, a very thin veneer of mudstone (Kimmeridge Clay) may overlie the uppermost sandstone unit and where this occurs, it has been included within the Birch Sandstone Member. |
| Thickness: |
Up to 55 m. |
| Geographical Limits: |
Restricted to a small part of block 16/12 on the western side of the South Viking Graben. |
| Parent Unit: |
Kimmeridge Clay Formation (KC)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea borehole 16/12-8 between the depthes 3954 and 4017 m below KB (Richards et al., 1993). |
| Reference Section |
North Sea borehole 16/12a-4 between the depths 4215.5 and 4286.5 m (Richards et al., 1993). |
| Reference(s): |
| 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 |
