| Computer Code: |
VAIL |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Selandian Age (GS)
— Selandian Age (GS) |
| Lithological Description: |
The Vaila Formation consists of medium to dark grey, variably silty mudstones with thick sandstone units present in most basinal sections. These sandstone units display a continuous gradation from thickly bedded, sandstone-dominated facies to thinly bedded facies in which sandstone and mudstone occur in more or less equal proportions. Facies variation within individual sandstone units is limited, however.
A thick unit of tuffaceous sandstone is present in well 205/9-1. Cores show this to consist of tuffaceous, locally pebbly sandstone grading to sandy tuffite (reworked tuff). Additional, thinner, tuffaceous sandstone units are identified lower in the section on the basis of wireline-log character.
Mudstone units within the Vaila Formation appear from cuttings description to be dominantly medium to dark grey with varying proportions of silt. |
| Definition of Lower Boundary: |
none recorded or not applicable
|
| Definition of Upper Boundary: |
none recorded or not applicable
|
| Thickness: |
In southern and central basinal sections the Vaila Formation is between 600 and 1000 m thick, with a maximum thickness of c. 1050 m. In northern basinal sections, however, the thickness is reduced to around 200 m. |
| Geographical Limits: |
UK north west margin. The Vaila Formation is of widespread occurrence, being absent only in some northern and eastern marginal sections, where it has been cut out by the base-Moray Group unconformity. |
| Parent Unit: |
Faroe Group (FARO)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 206/01- 2: 3618-4372 m (11870-14345 ft) (Knox et al., 1997). |
| Reference Section |
North Sea well 214/27- 1: 3402-4300 m (11161-14107 ft) (Knox et al., 1997). |
| Reference Section |
North Sea well 208/19- 1: 2280-2777.5 m (7480-9112 ft) (Knox et al., 1997). |
| Reference Section |
North Sea well 208/17- 1: 3331-3534.5 m (10929-11596 ft) (Knox et al., 1997). |
| Reference(s): |
| Mitchell, S M, Beamish, G W J, Wood, M V, Malacek, S J, Armentrout, M J, Damuth, J E, and Olson, H C. 1992. Paleogene sequence stratigraphic framework of the Faroe Basin. In: Parker, J R (ed.) Petroleum geology of Northwest Europe: proceedings of the 4th conference, 1011-1023. The Geological Society, London. |
| Shanmugam, G, Bloch, R B, Mitchell, S M, Beamish, G W J, Hodgkinson, R J, Damuth, J E, Straume, T, Syversten, S E, and Shields, K E. 1995. Basin-floor fans in the North Sea: sequence stratigraphic models vs. sedimentary facies. AAPG Bulletin 79, 477-512. |
| Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) |
| Knox, R W O'B, Holloway, S, Kirby, G A and Baily, H E. 1997. Stratigraphic nomenclature of the UK North West Margin. 2. Early Paleogene lithostratigraphy and sequence stratigraphy. British Geological Survey, Nottingham. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
