The BGS Lexicon of Named Rock Units — Result Details
Sugarbrook Member
| Computer Code: | SGBK | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Anisian Age (TA) — Anisian Age (TA) | ||
| Lithological Description: | The dominant lithology is pale red-brown and greenish grey sandstones. The sandstones are finer grained than in the underlying Finstall Member and large-scale cross-bedding is virtually absent. Interbedded red-brown and grey-green mudstones and siltstones are more common than in the Finstall Member. The sequence shows repeated fining-upward cycles, from sandstone to mudstone; intraformational conglomerates occur throughout. Sedimentary structures include ripple marks, flute casts, slump structures, mud cracks and convolute bedding. Micaceous bedding planes are common. In the type section, bioturbation, plant remains and Euestheria have been found in the lower c.15m, and acritarchs and pseudomorphs after halite occur above that level. | ||
| Definition of Lower Boundary: | The lower boundary is taken above the highest significant (>1 m) bed of sandstone with large scale cross bedding of the underlying Finstall Member. | ||
| Definition of Upper Boundary: | The upper boundary is taken at the top of the highest significant grey sandstone bed, above which red mudstones and siltstones of the MMG predominate over sandstone. | ||
| Thickness: | The thickest known sequence is 24.4 m, in the Sugarbrook No.3 Borehole. | ||
| Geographical Limits: | The member has only been mapped in the Bromsgrove area of Worcestershire but is likely to extend westwards to Little Witley [SO 78 63], Worcestershire. | ||
| Parent Unit: | Helsby Sandstone Formation (HEY) | ||
| Previous Name(s): | Passage Beds [Obsolete Name and Code: Use BOOC, SGBK, CLGB, MCH, UND, YED, MYS]
(-3236)
Waterstones [Obsolete Name and Code: Use DST, SGBK, TPSF] (-4008) Waterstones Group [Obsolete Name and Code: Use TPSF, SGBK, HEY] (-3089) |
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| Alternative Name(s): | Tarporley Siltstone Formation |
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| Stratotypes: | |||
| Type Section | From the Sugarbrook Pumping Station site, to the south-west of Bromsgrove, Worcestershire. Sugarbrook No. 3 Borehole (BGS Registered No. SO96NE/30), 22.9-67.3 m (Old et al., 1991). Scarce exposures in the Bromsgrove area, south and east of Kidderminster (Mitchell et al., 1962; Old et al., 1991). | ||
| Reference(s): | |||
| Richardson, L. 1928. The wells and springs of Warwickshire. Memoir of the Geological Survey of Great Britain. | |||
| Wills, L J. 1970. The Triassic succession in the central Midlands in its regional setting. Quarterly Journal of the Geological Society of London, Vol.126, 225-285. | |||
| Binney, E W. 1846. On the relation of the New Red Sandstone to the Carboniferous strata in Lancashire and Cheshire. Quarterly Journal of the Geological Society of London, Vol. 2, 12–26. | |||
| Mitchell, G H, Pocock, R W, and Taylor, J H. 1962. Geology of the country around Droitwich, Abberley and Kidderminster. Memoir of the Geological Survey of Great Britain, Sheet 182 (England and Wales). | |||
| Old R A, Hamblin, R J O, Ambrose, K, and Warrington G. 1991. Geology of the country around Redditch. Memoir of the British Geological Survey, Sheet 183 (England and Wales). | |||
| Ambrose, K, Hough, E, Smith, N J P, and Warrington, G. 2014. Lithostratigraphy of the Sherwood Sandstone Group of England, Wales and south-west Scotland. British Geological Survey Research Report RR/14/01. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||