| Computer Code: |
KPHA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Carnian Age (TC)
— Carnian Age (TC) |
| Lithological Description: |
The Keuper Halite Member comprises halite, in beds up to 20 m thick, with interbeds of red-brown mudstone and anhydritic mudstone; halite constitutes up to 80% of the member in the Sole Pit Basin (Cameron et al., 1992). The member typically shows predominantly low gamma-ray values and high velocities, and the mainly parallel-sided log signature representative of halite; narrow peaks of high gamma-ray and lower velocity values correspond to mudstone interbeds. |
| Definition of Lower Boundary: |
The base of the Keuper Halite Member is placed at the base of the main concentration of bedded halite within the Dudgeon Formation. It is characterized by an abrupt downward increase in gamma-ray values and a decrease in velocity. |
| Definition of Upper Boundary: |
The top of the Keuper Halite Member corresponds to the top of the Dudgeon Formation and is placed at a downward change from red-brown mudstones, with thin dolomite and anhydrite beds, of the Triton Formation, to halite. The boundary is marked by an abrupt downward decrease in gamma-ray values and a slight increase in velocity. |
| Thickness: |
The member exceeds 150 m in the southern part of the Sole Pit Basin (Cameron et al., 1992), with over 200 m present in Block 49/26, but elsewhere varies mostly between 30 and 100 m in thickness. |
| Geographical Limits: |
The Keuper Halite Member is recognized in a relatively small part of the area occupied by the Dudgeon Formation; it is the least extensive of the three halite members recognized in formations of the Haisborough Group but is considerably thicker than those present in the underlying Dowsing Formation. The principal occurrence, in quadrants 47, 48, 49 and 53, is centred on the Sole Pit Basin; small isolated occurrences are present farther north in quadrants 41, 42 and 43. |
| Parent Unit: |
Dudgeon Formation (DGSL)
|
| 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): 882-1036.5 m (2893-3401 ft) below KB (metric conversion revised). |
| Reference Section |
North Sea well 48/06- 22: 914-1035.5 m (2998-3397 ft) drilled depths, 805.5-895 m (2643-2937 ft) true vertical depths (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. |
| 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.) |
| Fisher, M J, and Mudge, D C. 1990. Triassic. In: Glennie, K W (ed.) Introduction to the petroleum geology of the North Sea, 191-218. Blackwell Scientific Publications, Oxford. |
| 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. |
| Warrington, G, Audley-Charles, M G, Elliott, R E, Evans, W B, Ivimey-Cook, H C, Kent, P E, Robinson, P L, Shotton, F W and Taylor, F M. 1980. A correlation of the Triassic rocks in the British Isles. Special Report of the Geological Society of London, No.13. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
