Fawes Wood Limestone Formation
Fawes Wood Limestone Formation (FWL), Carboniferous, Northern England Province
Fawes Wood Limestone Formation is part of the Great Scar Limestone Group
Name
The name is derived from Fawes Wood (SD 6955 9145), on the River Clough, Garsdale, Yorkshire (see Dunham and Wilson, 1985 and references therein[1]). The formation was first proposed by Burgess (1986[2]).
Lithology
The Fawes Wood Limestone Formation comprises mid to dark grey biomicrosparites and biomicrites (calcarenite, mainly grainstone and packstone) with silty or stylolitic partings and some porcellaneous micrites.
Genetic interpretation
Shallow marine carbonate
Stratotype
Reference sections in the formation include: the River Clough, Garsdale (SD 6967 9129 to 6961 9134) where the formation comprises biomicrites and medium-grained limestones 80.77 m thick (Burgess, 1986, p. 11[2]; Dunham and Wilson, 1985, p. 28[1]); part of the Beckermonds Scar Borehole (BGS Registration Number SD88SE/1) (SD 8636 8016) from about 143 to 200 m depth, where it comprises mid–dark grey limestone, chiefly medium-grain calcarenite (Wilson and Cornwell, 1982, p. 64[3]); and the BGS Raydale Borehole (BGS Registration Number SD98SW/1) (SD 9626 8474) from about 158 to 235 m depth. Dunham and Wilson (1985, p. 28, see also fig. 5, cols. 5 and 7[1]) summarised the formation as comprising about 56–81 m of dominantly dark grey and grey fine-grained grainstones and packstones with a few mudstone and siltstone beds.
Lower and upper boundaries
The formation conformably overlies the sandstones of the Ashfell Sandstone and biosparites of the Tom Croft Limestone formations (Figure 9, Column 17; Figure 15, Column 3).
The formation is conformably overlain by the limestones with interbedded sandstones, siltstones and numerous thin beds of mudstone of the Garsdale Limestone Formation.
Thickness
The formation ranges in thickness from 80.77 m in the River Clough to 55.80 m in the Beckermonds Scar Borehole (Dunham and Wilson, 1985[1]).
Distribution and regional correlation
Askrigg Block.
Age and biostratigraphical characterisation
Holkerian. Fossils include Siphonodendron martini, Linoprotonia sp., and ?Macrochilina sp. The lower part of the formation contains distinctive Holkerian assemblages with Lithostrotion minus, Siphonodendron sociale and Davidsonina carbonaria. Although it is lithologically similar to the Ashfell Limestone Formation, the upper limit of the Fawes Wood Limestone Formation is taken at a lower stratigraphical level.
References
- ↑ Jump up to: 1.0 1.1 1.2 1.3 Dunham, K C, and Wilson, A A.1985.Geology of the Northern Pennine Orefield: Volume 2, Stainmore to Craven.Economic Memoir of the British Geological Survey, Sheets 40, 41 and 50, parts 31, 32, 51, 60 and 61(England and Wales).
- ↑ Jump up to: 2.0 2.1 Burgess, I C.1986.Lower Carboniferous sections in the Sedbergh district, Cumbria.Transactions of the Leeds Geological Association, Vol. 11, 1–23.
- ↑ Wilson, A A, and Cornwell, J D.1982.The Institute of Geological Sciences Borehole at Beckermonds Scar, North Yorkshire.Proceedings of the Yorkshire Geological Society,Vol. 44, 59–88.