The BGS Lexicon of Named Rock Units — Result Details

Arngrove Spiculite Member

Computer Code: AGSP Preferred Map Code: AnS
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Pale grey, siliceous or calcareous sandstone or siltstone with abundant siliceous spicules of Rhaxella perforata (tetractinellid sponge).
Definition of Lower Boundary: An upward transition from the silty mudstones of the West Walton Formation or locally, fine-grained silty sands and clayey silts of the Temple Cowley Member of the Kingston Formation to coarser-grained, spiculitic sandstone.
Definition of Upper Boundary: An upward transition from spiculitic sand or sandstone, to non-spiculitic sand and calcareous sandstone of the Beckley Sand Member of the Kingston Formation, or marls and limestones of the Oakley Member of the Stanford Formation.
Thickness: Up to 4.2 m thick.
Geographical Limits: The area between Beckley, Wheatley and Brill north-east of Oxford as seen on the 1:50 000 sheet 237 (inset map), and passes south-westwards into the Temple Cowley Member. Restricted to sheet 237, although similar spiculites are present in the Purton area (sheet 252).
Parent Unit: Kingston Formation (KTON)
Previous Name(s): Arngrove Stone (-3158)
Rhaxella Chert [Obsolete Name And Code: See RIS] (RCH)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Brill No. 1 Borehole (SP61SE/10) 106.06 - 107.70 m. 
Type Area  Arngrove Farm (now Old Arngrove), near Brill, Bucks. 
Reference Section  M40 Borehole 10 (SP60NW/6), 10.20 - 13.68 m. 
Reference(s):
Wright, J K and Cope, J C W. In press. Oxfordian - Kimmeridgian Correlation Chart. In: A correlation of Jurassic rocks in the British Isles: Middle and Upper Jurassic. Cope, J C W (editor). Special Report of the Geological Society of London. 
Horton, A, Sumbler, M G, Cox, B M and Ambrose, K, 1995. Geology of the country around Thame. Memoir of the British Geological Survey, Sheet 237 (England and Wales). 
Cox, B M and Wright, J K, 2001. British Upper Jurassic stratigraphy (Oxfordian to Kimmeridgian). Geological Conservation Review Series, No. 21. (Peterborough: Joint Nature Conservation Committee.) 
Davies, A M. 1907b. Excursion to Dorton, Brill and Arngrove. Proceedings of the Geologists' Association, Vol. 20, 183-186. 
Arkell, W J, 1927. The Corallian rocks of Oxford, Berkshire and north Wiltshire. Philosophical Transactions of the Royal Society of London, Vol.B216, 67-181. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E237