| Computer Code: |
SLVP |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Cisuralian Epoch (PLC)
— Lopingian Epoch (PUL) |
| Lithological Description: |
The Silverpit Formation is characterized by reddish brown mudstones and siltstones, locally interbedded with units of halite and thin sandstones. The mudstones and siltstones are locally anhydritic and calcareous, and vary from soft to very hard and dense. The halites are translucent to off-white, pink and reddish brown, coarsely crystalline, brittle and hard, with occasional white patches of hard, amorphous anhydrite. Generally, the halites are thicker and more numerous in the lower part of the formation. The sandstones are generally reddish brown and grey, very fine to medium grained and argillaceous. |
| Definition of Lower Boundary: |
The lower boundary with the Lower Leman Sandstone is generally marked by a downward change from mudstone to sandstone, corresponding to a downward decrease in gamma-ray values (e.g. 48/6-25). Where the Lower Leman Sandstone is absent, mudstone or halite of the Silverpit Formation rests directly on the Coneybeare Group (Cameron, 1993) (e.g. 44/22-1). This boundary is typically associated with a downward increase in gamma-ray values. |
| Definition of Upper Boundary: |
Where the Silverpit Formation is overlain by the Upper Leman Sandstone, its top is normally marked by a downward increase in the proportion of mudstone, corresponding to a downward increase in gamma-ray values. Where the Upper Leman Sandstone is absent and the Silverpit Formation is overlain directly by the Kupferschiefer Formation (e.g. 43/12-1), the boundary is marked by a downward passage from black, organic-rich mudstone to red-brown mudstone. This is typically associated with a downward decrease in gamma-ray values and an increase in velocity. Where the Kupferschiefer Formation is locally absent, the Silverpit Formation is directly overlain by grey carbonate of the Zechsteinkalk Formation (e.g. 47/5a-4). |
| Thickness: |
It is thickest in the southwestern part of the Silverpit Basin, where it reaches about 350 m. |
| Geographical Limits: |
The Silverpit Formation is present across the northern parts of the Sole Pit Trough and Indefatigable Shelf, and extends across the Silverpit Basin and the Cleaver Bank High to the international boundary with the Dutch sector. It pinches out eastwards before reaching the English coast, and northwards against the North Dogger Shelf. To the south, the Silverpit Formation passes laterally into the coeval Leman Sandstone Formation. |
| 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 44/21- 1 (Rhys 1974, table 2, fig. 2): 3864.5-4185 m (12678-13730 ft) below KB (metric conversion of upper boundary revised and depth of base revised) (Johnson et al., 1994). |
| Reference Section |
North Sea well 48/06- 25: 2848.5-2905 m (9343-9531 ft) (Johnson et al., 1994). |
| Reference(s): |
| Johnson, H, Warrington, G and Stoker, S J. 1994. 6. Permian and Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| Cameron, T D J. 1993. 5. Carboniferous and Devonian of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. |
| Glennie, K W. 1990. Lower Permian - Rotliegend. In: Glennie, K W (ed.) Introduction to the Petroleum Geology of the North Sea, Blackwell Scientific Publications, p. 120 - 152. |
| NAM and RGD (Nederlandse Ardolie Maatschappij and Rijks Geologische Dienst) 1980. Stratigraphic nomenclature of the Netherlands. Transactions of the Royal Dutch Geological and Mining Society of Delft. |
| Rhys, G H. 1974. A proposed standard lithostratigraphic nomenclature for the southern North Sea and an outline structural nomenclature for the whole of the (UK) North Sea. Report of the Institute of Geological Sciences, 74/8. |
| George, G T, and Berry, J K. 1993. A new lithostratigraphy and depositional model for the Upper Rotliegend of the UK Sector of the Southern North Sea. In: North, C P, and Prosser, D J (eds.) Characterization of fluvial and aeolian reservoirs. Geological Society, London, Special Publication No.73, 291-319. |
| Glennie, K W. 1972. Permian Rotliegendes of northwest Europe interpreted in light of modern desert sedimentation studies. AAPG Bulletin 56, 1048-1071. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
