| Computer Code: |
MAVO |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Cisuralian Epoch (PLC)
— Cisuralian Epoch (PLC) |
| Lithological Description: |
The Margareta Volcanics Formation is made up of lavas, broadly similar to those described from the Nun Volcanics Formation, siltstones and sandstones. The siltstones are red or brown to green or grey, firm to hard, blocky, slightly calcareous and contain volcaniclastic material whereas the sandstones are colourless or red stained, fine to coarse, subrounded, argillaceous, pebbly or conglomeratic. |
| Definition of Lower Boundary: |
The base of the formation is not defined, as no wells have penetrated it. |
| Definition of Upper Boundary: |
The top of the Margareta Volcanics Formation is marked by a downward transition from argillaceous limestones and anhydrites of the Turbot Anhydrite Formation in the Møre Basin, to a mixed succession of lavas, siltstones and sandstones. On wireline logs, this change is represented by a sharp downward increase in gamma-ray log values and a decrease in velocity. |
| Thickness: |
In the one well where it is known, it attained an unbottomed thickness of 53 m. |
| Geographical Limits: |
The Margareta Volcanics Formation has only been encountered in well 220/26-2 on the Margareta Spur. Hitchen and Ritchie (1987) have suggested that similar successions may be present nearby, below well TD in 210/4-1 and 210/13-1. |
| Parent Unit: |
Rotliegend Group (RLG)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 220/26- 2: 4189-4242 m TD (13743-13917 ft) (Ritchie et al., 1996). |
| Reference(s): |
| Hitchen, K, and Ritchie, J D. 1987. Geological Review of the West Shetland area. In: Brooks, J, and Glennie, K W (eds.) Petroleum geology of North West Europe. (London: Graham and Trotman), 737-749. |
| Ritchie, J D, Gatliff, R W and Riding, J, 1996. 1. Pre - Tertiary lithostratigraphy. In: Stratigraphic Nomenclature of the UK North West Margin. British Geological Survey, Nottingham. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
