| Computer Code: |
SLSA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Aptian Age (KP)
— Aptian Age (KP) |
| Lithological Description: |
Sandstones with minor interbedded calcareous mudstone and chalky mudstone. Sandstones are pale grey, fine- to coarse- grained and vary from well sorted to poorly sorted and friable to well cemented. Quartz dominates, but pyrite, glauconite and carbonaceous materialare also recorded. In well 15/17-23 the member has a coarse-grained to granular and faintly laminated base and fines upward to coarse to medium- grained and moderately sorted sandstone. The massive sandstone succession contains lithic fragments of quartzite, limestone, lignite and mudstone rip-up clasts. Zones of nodular calcite cement show as spikes on the sonic log. The sandstones usually display "blocky" wireline log signatures. |
| Definition of Lower Boundary: |
The lower boundary is marked by a downward passage from sandstones into grey chalky mudstones and calcareous mudstones (Valhall Formation, informal unit V6). THe boundary coincides with a downward increase in gamma-ray values and usually a downward decrease in sonic velocity. Locally (e.g. 15/17-21) the Sloop Member overlies dark grey, organic rich mudstones of the Valhall Formation (informal unit V5 "Fischschiefer"). |
| Definition of Upper Boundary: |
The top is marked by a downward passage from grey and brown chalky mudstones and calcareous mudstones (Valhall Formation, informal unit 6) to sandstone. It coincides with a sharp downward reduction in gamma-ray log values and an increase in velocity. |
| Thickness: |
Locally over 20 m. |
| Geographical Limits: |
North Sea Block 15/17. |
| Parent Unit: |
Valhall Formation (VALH)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 15/17- 22 at 3549-3571 m, below KB (Johnson and Lott, 1993). |
| Reference Section |
North Sea well 15/17- 21 at 3681-3688.5 m (Johnson and Lott, 1993). |
| Reference(s): |
| Johnson, H and Lott, G K. 1993. 2. Cretaceous 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 |
