| Computer Code: |
BNS |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Early Triassic Epoch (TE)
— Early Triassic Epoch (TE) |
| Lithological Description: |
The Bunter Sandstone Formation comprises red, orange, occasionally white or colourless, sandstones, interbedded with red, grey, rarely green, occasionally dolomitic, mudstone and silty or sandy mudstone. The sandstone varies from fine to coarse, and contains varying amounts of dolomitic or anhydritic cements. |
| Definition of Lower Boundary: |
The base of the Bunter Sandstone Formation is defined by a downward change from a dominantly arenaceous sequence to the dominantly argillaceous Bunter Shale Formation. The boundary is usually clear and marked by a downward increase in gamma-ray values but may be less distinct towards the London-Brabant Platform and the eastern UK onshore area where the formation rests upon the Amethyst Member of the Bunter Shale Formation. |
| Definition of Upper Boundary: |
The top of the Bunter Sandstone Formation is defined by a sharp downward change from red-brown mudstones, with dolomite and evaporite interbeds, to a thick sandstone-dominated sequence. This boundary corresponds to an abrupt downward decrease in gamma-ray values and an increase in velocity. Comparison of log profiles within the Bunter Sandstone Formation suggests that the boundary is an angular unconformity at which beds within the formation are truncated and where overstep by the overlying Dowsing Formation occurs. For example, a unit forming the upper part of the formation in the type section is absent from wells such as 48/7b-3 and 41/24a-2. |
| Thickness: |
The formation is thickest in the Sole Pit Basin where it locally exceeds 350 m. The formation thins towards the London-Brabant Platform, the Cleaver Bank High and the Mid North Sea High (Cameron et al., 1992). |
| Geographical Limits: |
The Bunter Sandstone Formation is present throughout most of the UK sector of the Southern North Sea. |
| Parent Unit: |
Bacton Group (BACT)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 49/21- 2 (Rhys, 1974): 1375.5-1683 m (4512-5522 ft) below KB (metric conversion revised; revised base). The base of the formation in this section is here revised from 1695.5 m (5563 ft, metric conversion revised) (Rhys, 1974) to the level of a regionally consistent log-marker. |
| Reference Section |
North Sea well 41/24a- 2: 504-656.5 m (1654-2154 ft) (Johnson et al., 1994). |
| Reference Section |
North Sea well 48/07b- 3: 1535-1885 m (5036-6184 ft) (Johnson et al., 1994). |
| Reference Section |
North Sea well 53/02- 3: 1082-1429.5 m (3550-4690 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, Crosby, A, Balson, P S, Jeffery, D H, Lott, G K, Bulat, J, and Harrison, D J. 1992. The geology of the southern North Sea. United Kingdom offshore regional report. (London: HMSO for the British Geological Survey.) |
| Geiger, M E, and Hopping, C A. 1968. Triassic stratigraphy of the southern North Sea Basin. Philosophical Transactions of the Royal Society of London B254, 1-36. |
| 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. |
| Van der Zwan, C J, and Spaak, P. 1992. Lower to Middle Triassic sequence stratigraphy and climatology of the Netherlands, a model. Palaeogeography, Palaeoclimatology, Palaeoecology 91, 277-290. |
| Warrington, G, and Ivimey-Cook, H C. 1992. Triassic. In: Cope, J C W, Ingham, J K, and Rawson, P F (eds.) Atlas of palaeogeography and lithofacies. Geological Society, London, Memoir No. 13, 97-106. |
| Fisher, M J. 1979. The Triassic palynofloral succession in the Canadian Arctic Archipelago. AASP Contributions Series 5B, 83-100. |
| Reitz, E. 1988. Palynostratigraphie des Buntsandsteins in Mitteleuropa. Geologisches Jahrbuch Hessen 116, 105-112. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E085
E066
E075
E114
E127
E162
|
