The BGS Lexicon of Named Rock Units — Result Details
Burns Sandstone Member
| Computer Code: | BNSA | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Kimmeridgian Age (JD) — Berriasian Age (KR) | ||
| Lithological Description: | Very fine to medium-grained (locally coarse to very coarse), poorly to moderately sorted sandstones, variously cemented with carbonate. Interbedded with grey and brown to black siltstones and mudstones typical of the Kimmeridge Clay Formation. | ||
| Definition of Lower Boundary: | The base is placed either at a down-section change from sandstone to mudstone or at a downward transition from sandstone-dominated to mudstone-dominated sediments. This is reflected in the gamma-ray values, which may be sharp (e.g.well 20/2-2) or gradual (e.g. 20/2-5). Velocity decreases downwards. NB: There is potential for confusion as the thin sandstones which occur within the Kimmeridge Clay and below the main sandstone unit of the present member (e.g. 12/24-2) are not included here. | ||
| Definition of Upper Boundary: | The top is usually defined by a downward change from mudstones (Kimmeridge Clay Formation) to sandstones or interbedded sandstones and mudstones. The boundary is marked by a down-section decrease in gamma-ray values and an increase in velocity (NB: thin sandstones, which may occur within the overlying Kimmeridge Clay Formation, are not included in the member). Locally, sandstones of the Cromer Knoll Group overlie the Burns Sandstone Member and the boundary is difficult to identify without biostratigraphy. However, in some sections, (e.g. well 20/2-5) there is a down-section change from thickly bedded sandstones (of the Cromer Knoll Group) to thinly bedded sandstones with interbedded mudstones (Burns Sandstone Member). Mudstones associated with the Cromer Knoll Group sandstones are more calcareous than those in the Burns Sandstone Member, so that gamma-ray values are lower and velocities are higher. | ||
| Thickness: | Variable to 1344 m and probably thicker adjacent to hanging walls of major syndepositional faults. | ||
| Geographical Limits: | Inner Moray Firth, Halibut Shelf and NW part of the South Halibut Basin (quadrants 11-15, 17, and 20-21). | ||
| Parent Unit: | Kimmeridge Clay Formation (KC) | ||
| Previous Name(s): | Cromarty Sand Member
(-5148)
Ettrick Sandstone (-5149) Helmsdale Boulder Beds Equivalent (-5150) Lower Hot Shale (-5151) Upper Hot Shale (-5152) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | North Sea well 12/23- 2 between 957.5 and 1382.5 m (Richards et al., 1993). | ||
| Reference Section | North Sea well 20/02- 2 between 3191.5 and 3263 m (Richards et al., 1993). | ||
| Type Section | North Sea well 12/24- 2 between 1538 and 2882 m below KB (Richards et al., 1993). | ||
| Reference Section | North Sea well 20/02- 5 between 2927 and 3285.5 m (Richards et al., 1993). | ||
| Reference(s): | |||
| Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic of the Central and Northern North Sea. In: Knox, R W O'B and Cordey, W G (eds.). Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. | |||
| Stevens, V. 1991. The Beatrice Field, Block 11/30a, UK North Sea. In: Abbotts, I L (ed.) United Kingdom oil and gas fields 25 years commemorative volume. Memoir of the Geological Society, London, 14, 245-252. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||