The BGS Lexicon of Named Rock Units — Result Details
Spilsby Sandstone Formation
| Computer Code: | SYS | Preferred Map Code: | SyS |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Tithonian Age (JI) — Valanginian Age (KV) | ||
| Lithological Description: | Onshore, the Formation comprises two members that are further divided. Upper Spilsby Sandstone Member: Thin, coarse-grained, grey or brown pebble sandstone with iron ooliths (Ferruginous Grit of Swinnerton, 1937). Underlain by fine-to medium-grained, buff, yellow and white sands with sparse calcareous "doggers" (the upper part of Swinnerton's 1937, "Glauconitic Sands"). The latter sands become coarser and greener towards the base of the Member. A bed of phosphatic nodules and small (generally chert) pebbles occurs at the base (the Mid Spilsby Nodule Bed of Casey, 1963, 1973). Lower Spilsby Sandstone Member: Coarse-grained, pebbly, glauconitic sands and sandstones with calcareous "doggers" and sporadic phosphatic nodules towards the top (this unit equates with the lower part of Swinnerton's, 1937, "Glauconitic Sands"). The base of the Member comprises a thin grey sandstone with phosphatic nodules (the "Basement Beds" of Swinnerton, 1937, and Beds A and D of Swinnerton, 1935). Offshore, the Spilsby Sandstone consists of grey to white, poorly to well cemented, very fine- to medium- grained sandstone with interbedded green to blue-green, firm to fissile mudstone. Glauconitic and phosphatic grains are common. Pebbly phosphatic horizons within and at the base of some sequences produce prominent gamma-ray spikes on wireline logs. The upper part of the formation comprises more massive sandstones and the lower part of the formation contains more interbedded mudstones (e.g. Well 48/17a-2). On this basis the formation has been informally divided (SP1 and SP2) by Lott and Knox (1994). | ||
| Definition of Lower Boundary: | Onshore, a downsection change from grey sandstone with phosphatic nodules (the "Basement Beds" of the Lower Spilsby Sandstone Member) to mudstone of the Kimmeridge Clay Formation. Offshore, the base is defined by a downward change from variably cemented sandstones (Spilsby Sandstone Formation) to dark, variably calcareous mudstone (Kimmeridge Clay). There is a marked increase in gamma-ray values and velocity generally becomes more regular. | ||
| Definition of Upper Boundary: | Onshore, down-section change from purple-grey and brown mottled mudstones with sporadic iron ooliths (Hundlsby Clay Member, Claxby Ironstone Formation) or argillaceous oolitic ironstone (Claxby Ironstone Formation) to pale yellow, medium-grained sand and sandstone (Upper Spilsby Sandstone Member). Offshore the upper boundary is defined by a marked downward change from calcareous mudstones to sandstones. This corresponds with a reduction in gamma-ray values and generally higher, irregular sonic log profile relating to the amount of carbonate cement present. | ||
| Thickness: | Onshore, to c.24 m. Offshore generally less than 50 m, but locally over 250 m. | ||
| Geographical Limits: | Onshore, the Spilsby Sandstone Formation is restricted to the southern part of Lincolnshire. It extends offshore into The Wash, but its extent is unknown as within a short distance it passes laterally into the lower part of Sandringham Sand Formation (Wingfield et al., 1978). Offshore in the Southern North Sea, the formation has been recognized in quadrants 47, 48, and 51-54. In the offshore region it forms the basal part of the Cromer Knoll Group (Lott and Knox, 1994). It is not clear how the Spilsby Sandstone Formation (offshore) relates to the Spilsby Sandstone Formation and the Sandringham Sand Formation (onshore). | ||
| Parent Unit: | Cromer Knoll Group (CRKN) | ||
| Previous Name(s): | Spilsby Beds of Spilsby Series [Obsolete Name and Code: Use SYS]
(-4915)
Spilsby Sandstone [Obsolete Name and Code: Use SYS] (-3066) Greensand And Sandstone (-556) Lower Sand and Sandstone [Obsolete Name and Code: Use CI, SYS] (*596) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | North Sea well 48/22- 2 at 417-435 m (Rhys, 1974; emended by Lott and Knox, 1994). | ||
| Reference Section | North Sea well 14/17a- 2 at 661-792 m (Rhys, 1974; Lott and Knox, 1994). | ||
| Reference Section | North Sea well 48/23- 1 at 769-905.5 m (Rhys, 1974; Lott and Knox, 1994). | ||
| Reference Section | North Sea well 53/02- 5 at 836-1104 m (Rhys, 1974; Lott and Knox, 1994). | ||
| Reference Section | Skegness Borehole between the depths 107.37 and 116.8 m. | ||
| Reference Section | Boston Corporation Waterworks, Fordington, boreholes, 8 km north of Spilsby (Swinnerton, 1935, emended by Casey, 1973). | ||
| Reference Section | Railway cutting between Benniworth and Donnington-on-Bain (Casey, 1973). | ||
| Reference Section | Nettleton Top Barn, southwest of Caistor (Casey, 1973). | ||
| Reference(s): | |||
| Dikes, W H and Lee, J W. 1837. Outlines of the Geology of Nettleton Hill, Lincolnshire. The Magazine of Natural History, I [No.11], 562-566. | |||
| Casey, R. 1963. The dawn of the Cretaceous period in Britain. Bulletin of the South East Union of Scientific Societies, 117, 1-15. | |||
| Lott, G K and Knox, R W O'B. 1994. 7. Post-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. | |||
| Casey, R 1973. The ammonite succession at the Jurassic-Cretaceous boundary in Eastern England. In Casey, R and Rawson, P F [editors], The Boreal Lower Cretaceous [Liverpool: Seel House Press.] | |||
| 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. | |||
| Swinnerton, H H. 1937 (for 1936). A monograph of British Cretaceous Belemnites, Part 11. Monograph of the Palaeontographical Society. | |||
| Jukes-Browne, A.J. 1887. The Geology of part of east Lincolnshire. Memoir of the Geological Survey of the United Kingdom, 181pp. | |||
| 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. | |||
| Swinnerton, H H. 1935. The rocks below the Red Chalk of Lincolnshire and their cephlopod fauna. Quarterly Journal of the Geological Society, London, 91, 1-46. | |||
| Judd, J W. 1867. On the strata which form the base of the Lincolnshire Wolds. Quarterly Journal of the Geological Society, London, 23, 227-251. | |||
| Strahan, A. 1886. Notes on the relations of the Lincolnshire Carstone. Quarterly Journal of the Geological Society, London, 42, 481-493. | |||
| Wingfield, R T R, Evans, C D R, Deegan, S E and Floyd, R. 1978. Geological and geophysical survey of The Wash. Report of the Institute of Geological Sciences, 78/18, 32pp. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E129 E103 E081 E089 E090 E091 E115 | |||