| Computer Code: |
PUSA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Berriasian Age (KR)
— Hauterivian Age (KH) |
| Lithological Description: |
The member comprises sandstones with interbedded siltstones and mudstones. Sandstones are very fine- to very coarse- grained, poorly sorted, quartzose, white to pale grey and contain minor amounts of glauconite, carbonaceous debris and mica. Thin calcite-cemented zones are marked by high velocity spikes on the wireline log (e.g. 12/30-1). The siltstones and mudstones are pale to dark grey or tan, micromicaceous, variably calcareous to non-calcareous and blocky to fissile. Sporadic thin, off-white, argillaceous and sandy limestones are locally present. |
| Definition of Lower Boundary: |
The base is normally defined by a downward change from sandstone (Punt Sandstone Member) to grey, red-brown or varicoloured calcareous mudstones with thin interbedded argillaceous limestones and chalky mudstones (Valhall Formation). In some section the base of the Punt Sandstone Member lies within the Valhall Formation unit 2 (e.g.13/29-2) (Johnson and Lott, 1993). On wireline logs the lower boundary is marked by a downward increase in gamma-ray values and a decrease in velocity. Locally the Punt Sandstone Member lies directly on the Kimmeridge Clay Formation (e.g. well 30/30-1 and 13/27-2). In this case the base is difficult to identify, but the mudstone of the Punt Sandstone Member is generally more calcareous and less carbonaceous than the Kimmeridge Clay Formation. |
| Definition of Upper Boundary: |
The top of the Punt Sandstone Member is normally defined by a downward change from grey, calcareous and micromicaceous mudstones (Valhall Formation) to sandstones and interbedded mudstones. |
| Thickness: |
Usually 50-100 m, but locally 300 m. |
| Geographical Limits: |
Inner Moray Firth (Quadrants 11-13 and 17). |
| Parent Unit: |
Wick Sandstone Formation (WISA)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 12/30- 1 at 1457-1556 m below KB (Johnson and Lott, 1993). |
| Reference Section |
North Sea well 13/29- 2 at 2188.5-2291.5 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. |
| Stevens, V. 1991. The Beatrice Field, Block 11/30a, UK North Sea. In: Abbotts, I L (ed.) United Kingdom oil and gas fields 25 years commemorative volume. Memoir of the Geological Society, London, 14, 245-252. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
