The BGS Lexicon of Named Rock Units — Result Details
Dunalastair Quartzite Formation
Computer Code: | DUNQ | Preferred Map Code: | DunQ |
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Status Code: | Full | ||
Age range: | Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ) | ||
Lithological Description: | Quartzite and quartzitic psammitic, beds 100 - 300m thick well developed; less feldspathic than Grampian Group psammites. Cross-bedding shown by feldspar-rich and heavy mineral-rich laminae. | ||
Definition of Lower Boundary: | Sharp contact with underlying Grampian Group psammites. | ||
Definition of Upper Boundary: | Sharp boundary with Dunalastair Semipelite Formation, marked by change from quartzite to mixed psammite and semipelite. | ||
Thickness: | 0 - 90m; probably much tectonic thinning. | ||
Geographical Limits: | Main development in Strath Fionan [NN 7257 7556]. Also occurs sporadically in attenuated form from closure of Errochty Synform [NN 712 671] and as far east as tributary of Allt Kynachan [NN 7609 5670]. Also occurs at the culmination caused by the intersection of the Clunes and Bohespic antiforms [NN 745 633]. Not present east of the Loch Tay Fault, where it may have been tectonically excised; however some of the rocks of the 'Banvie Burn Series' may be equivalent. | ||
Parent Unit: | Lochaber Subgroup (DALO) | ||
Previous Name(s): | Quartzite Within Struan Flags
(-877)
Lower Beoil Banded Quartzite [Obsolete Name and Code: Use DUNQ] (-3377) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Type Section | 600m north-east of Lochan an Daim on transect A-A' (Fig.4 of Treagus, J E. 2001). | ||
Reference(s): | |||
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. | |||
Treagus, J E. 2001. Solid geology of the Schiehallion district. Memoir of the British Geological Survey, Sheet 55W (Scotland). | |||
Thomas, P R, 1980. The stratigraphy and structure of the Moine rocks north of the Schiehallion Complex, Scotland. Journal of the Geological Society, London, Vol.137, 469-482. | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
S055 |