| Computer Code: |
YASA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Barremian Age (KB)
— Aptian Age (KP) |
| Lithological Description: |
The member comprises very fine- to coarse- grained sandstones with minor interbedded calcareous mudstones. Sandstones are mainly quartzose, but with traces of glauconite and pyrite. Sorting varies from good to poor. Sandstones have a blocky gamma-ray signature, with high velocity spikes where thin calcite cemented zones occur. |
| Definition of Lower Boundary: |
The boundary is marked by a sharp downward passage from sandstones into calcareous mudstones, chalky mudstones and argillaceous limestones (Valhall Formation, informal unit V4) (Johnson and Lott, 1993). |
| Definition of Upper Boundary: |
The boundary is a downward passage frrom dark grey, non-calcareous, organic rich mudstones (Valhall Formation, informal unit V5/"Fischschiefer") into sandstone. There is a marked downward decrease in gamma values and a downward increase in velocity. |
| Thickness: |
Up to c. 20 m. |
| Geographical Limits: |
North Sea Block 15/17, around the Saltire Field. |
| 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- 21 at 3689.5-3710 m below KB (Johnson and Lott, 1993). |
| Reference Section |
North Sea well 15/17- 12 at 3248.5-3251.5 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. |
| Casey, B J, and Romani, R S. 1992. Reservoir geology of the Saltire Field, Witch Ground Graben, North Sea. Bulletin des Centres Recherches Exploration-Production Elf Aquitaine, 16, 235-252. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
