The BGS Lexicon of Named Rock Units — Result Details

Crinan Subgroup

Computer Code: DBCN Preferred Map Code: Crin
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Coarse-grained quartzite present in Argyll at base of subgroup; upper part of subgroup in Argyll and whole of subgroup elsewhere formed of interbedded semipelite and pelite with minor psammite - this facies denotes the commencement of deep-water turbiditic sedimentation. Gritty psammite and semipelite near top in Glen Dochart - Kikin.
Definition of Lower Boundary: Incoming of coarse pebbly quartzite or psammite at base of Crinan Grit or Upper Erins Quartzite (Argyll); change from calcareous pelite or volcaniclastic rocks to non-calcareous turbiditic semipelite, pelite and psammite (Perthshire to Banffshire).
Definition of Upper Boundary: Bottom of lowest limestone bed in Loch Tay Limestone Formation where present; from Glen Clova to Deeside change from dominant semipelite to psammite or quartzite with calcareous beds.
Thickness: 1.5-3km
Geographical Limits: Connemara; North Mayo; Donegal; Newtown Stewart to east of Strabane; Armoy to Torr Head; Kintyre, Knapdale; Crinan to Loch Awe; from Loch Fyne, via Tyndrum, Loch Tay, Loch Tummel, Glen Shee, Deeside, Donside and Ladder Hills to the coast from Aberdeen to Ellon, Peterhead to Fraserburgh, and Portsay to Boyne Bay.
Parent Unit: Argyll Group (ARGY)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Knapdale and mid-Argyll. (Roberts, J L, 1977). 
Reference(s):
Treagus, J E. 2001. Solid geology of the Schiehallion district. Memoir of the British Geological Survey, Sheet 55W (Scotland). 
Roberts, J L, 1977. The Dalradian rocks of Knapdale and North Kintyre. Scottish Journal of Geology, Vol.13, 113-124. 
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
Harris, A L and Pitcher, W S, 1975. The Dalradian Supergroup. "In" Harris, A L, Shackleton, R M, Watson, J, Downie, C, Harland, W B and Moorbath, S. A correlation of the Precambrian rocks in the British Isles. Geological Society Special Report, No.6. p.52-75. Scottish Academic Press, Edinburgh. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S036 S067 S038 S096 S086 S046 S047 S047 S012 S020 S028 S029 S037 S037 S045 S045 S046 S047 S054 S055 S055 S056 S065 S065 S066 S066 S075 S076 S085 S086 S087 S087 S096 S097 N08 S029 S019