| Computer Code: |
MKHA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Anisian Age (TA)
— Anisian Age (TA) |
| Lithological Description: |
The Muschelkalk Halite Member comprises halite with thin interbeds of red-brown mudstone and anhydrite. The member typically shows low gamma-ray values and high velocities and a mainly parallel-sided log signature representive of halite; narrow peaks of high gamma-ray and lower velocity values correspond to mudstone interbeds. |
| Definition of Lower Boundary: |
The base of the Muschelkalk Halite Member is placed at the downward change from halite to red-brown mudstones, with beds of dolomite and some anhydrite, in the upper part of the Dowsing Formation. The boundary is marked by an abrupt downward increase in gamma-ray values and a decrease in velocity. |
| Definition of Upper Boundary: |
The top of the Muschelkalk Halite Member is placed at the downward change from red-brown mudstones, with beds of dolomite and some anhydrite, to halite in the upper part of the Dowsing Formation. The boundary is marked by an abrupt downward decrease in gamma-ray values and a slight increase in velocity. |
| Thickness: |
The member is commonly between 30 and 60 m in thickness but exceeds 60 m in the southern part of the Sole Pit Basin and several other areas, principally adjacent to the Cleaver Bank High (Cameron et al., 1992). |
| Geographical Limits: |
The Muschelkalk Halite Member is recognized over about half the area occupied by the Dowsing Formation; it is less extensive than the Röt Halite Member, lower in the Dowsing Formation, but occurs over a greater area than the Keuper Halite Member in the succeeding Dudgeon Formation. The member is present from the Cleaver Bank High westwards to the Sole Pit Basin, from where it extends northwards and northeastwards into the North Dogger Shelf and Silver Pit Basin areas. |
| Parent Unit: |
Dowsing Formation (DWDL)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
North Sea well 49/21- 3: 1063-1126 m (3488-3695 ft) (Johnson et al., 1994). |
| Type Section |
North Sea well 49/21- 2 (Rhys, 1974): 1210.5-1250.5 m (3972-4103 ft) below KB (metric conversion revised). Rhys (1974) regarded the member as possibly faulted against underlying Dowsing Formation mudstones and illustrated potentially missing beds with a section from well 49/22-2; the characters of the lower part of the member are better represented in the reference sections. |
| Reference Section |
North Sea well 43/26- 7: 1116-1177 m (3662-3862 ft) drilled depths, 1116-1177 m (3662-3861 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.) |
| 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. |
| 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
