The BGS Lexicon of Named Rock Units — Result Details

Gunthorpe Member
Computer Code: GUN Preferred Map Code: Gun
Status Code: Full
Age range: Anisian Age (TA) — Ladinian Age (TD)
Lithological Description: Mudstone, red-brown, with subordinate dolomitic siltstone and fine-grained sandstone, greenish grey, common gupsum veins and nodules.
Definition of Lower Boundary: Conformable, gGradational upward passage from dominantly finely laminated mudstone and sandstone of Radcliffe Member into blocky, deformed mudstone of the Gunthorpe Member.
Definition of Upper Boundary: Conformable, at abrupt base of lowest pale grey sandstone bed of the Cotgrave Sandstone Member, overlying red-brown blocky mudstone of the Gunthorpe Member.
Thickness: 70-90m (71m in Cropwell Bridge borehole, SK63NE/28)
Geographical Limits: Mapped at surface in south Nottinghamshire and Leicestershire; traceable using geophysical logs in subsurface throughout East Midlands and Northeast England.
Parent Unit: Sidmouth Mudstone Formation (SIM)
Previous Name(s): Carlton Formation + Harlequin Formation (-3449)
Harlequin Formation [Obsolete Name And Code: Part Of GUN] (HRQ)
Carlton Formation [Obsolete Name And Code: Part Of GUN] (CRLF)
Gunthorpe Formation (-1578)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cropwell Bridge Borehole (SK63NE/28), near Cropwell Bishop, Nottinghamshire; depth range 84.9m-154.7m. Curated core held at BGS Keyworth. 
Reference Section  Fulbeck 1 Borehole (SK85SE/25), Fulbeck, Lincolnshire; depth range 200.1m-287.3m. Curated core held at BGS Keyworth. 
Reference Section  Surface section in river cliff beside River Trent at Gunthorpe, Nottinghamshire; on the southeastern bank adjacent to the weir. 8m section of the middle part of the member. 
Reference(s):
Howard, A S, Warrington, G, Ambrose, K, and Rees, J G. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. British Geological Survey Research Report, RR/08/04. 
Charsley, T J, Rathbone, P A and Lowe, D J, 1990. Nottingham: A geological background for planning and development. British Geological Survey Technical Report WA/90/1. 
Elliott, R E 1961. The stratigraphy of the Keuper Series in southern Notinghamshire. Proceedings of the Yorkshire Geological Society, Vol.33, 197-231. 
Howard, A S, Warrington, G, Carney, J N, Ambrose, K, Young, S R and Pharaoh, T C. In press. Geology of the country around Nottingham. Memoir of the British Geological Survey, Sheet 126 (England and Wales). 
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. 
Charsley, T J. 1989. Geology of the Nottingham (south) district: 1:10,000 Sheet SK63NE and part of 1:50,000 Sheet 126 (Nottingham) and Sheet 142 (Melton Mowbray). British Geological Survey Technical Report, Onshore Geology Series, 89/4. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E126 E127 E142 E141
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