The BGS Lexicon of Named Rock Units — Result Details

Meall Dubh Quartzite Formation

Computer Code: MEDQ Preferred Map Code: MeDQ
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Quartzite, feldspathic, with heavy-mineral laminae, originally pebbly but now strongly recrystallised and flattened; cross-bedding visible in places.
Definition of Lower Boundary: At base of transitional facies, c.2 - 3m thick, of finely-bedded fine-grained silty quartzite with black graphitic laminae which occurs just above contact with Meall Dubh Graphitic Schist Formation.
Definition of Upper Boundary: Sharp boundary to finely-laminated semipelite of Strath Fionan Banded Semipelite Formation.
Thickness: 10 - 180m in Sheet 55W; shows much tectonic thinning compared with Beinn a'Ghlo/Appin Quartzite.
Geographical Limits: From Allt Druidhe [6424 5694] sporadically to Allt na Moine Biudhe [NN 7077 6112] and then continuously to south bank of Allt Kinardochy [7789 5727]. Not present east of the Loch Tay Fault, where its place is taken by the Beinn a'Ghlo Quartzite Formation.
Parent Unit: Ballachulish Subgroup (DABH)
Previous Name(s): Beinn A'Ghlo Quartzite Formation (*185)
Meall Dubh Quartzite (-1060)
Appin Quartzite (*921)
Alternative Name(s): Appin Quartzite
Beinn A'Ghlo Quartzite Formation
Stratotypes:
Type Section  South side of Meall Dubh, as far as road through Strath Fionan. 
Reference(s):
Smith, R A and Harris, A L, 1976. The Ballachulish rocks of the Blair Atholl district. Scottish Journal of Geology, Vol.12, 153-157. 
Treagus, J E. 2001. Solid geology of the Schiehallion district. Memoir of the British Geological Survey, Sheet 55W (Scotland). 
Harris, A L, Haselock, P J, Kennedy, M J and Mendum, J R, 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland. 33-53 in Gibbons, W E and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, London, No.22. 
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
Treagus, J E and King, G, 1978. A complete Lower Dalradian succession in the Schiehallion district, central Perthshire. Scottish Journal of Geology, Vol.14, 157-166. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S055