The BGS Lexicon of Named Rock Units — Result Details

Allt A'Chuirn Quartzite Member

Computer Code: CHUI Preferred Map Code: CHUI
Status Code: Full
Age range: Cryogenian Period (AC) — Cryogenian Period (AC)
Lithological Description: 10 to 30cm-thick layers of quartzite, commonly ribbed in appearance; muscovitic semipelite typically accounts for less than 10% of the lithology, The base is gradational with the underlying part of the Beinn an Dothaidh Formation.
Definition of Lower Boundary: The base is gradational with the underlying part of the Beinn an Dothaidh Formation, with an upwards change to quartzite as the dominant lithology.
Definition of Upper Boundary: Abrupt change to the more uniform garnetiferous semipelite rocks of the Beinn Dorain Semipelite Formation.
Thickness: c 200m thickness is observed in the Allt a'Chuirn section but is greatly thickened by the effects of folding, estimated stratigraphical thickness is in the order of 30 to 50m.
Geographical Limits: The Member has a restricted occurance on the southern slopes of Beinn a' Chuirn, upper Auch Gleann. Sheet 46W (Crianlarich).
Parent Unit: Beinn An Dothaidh Formation (DOTH)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Allt a'Chuirn (Beinn a'Chuirn), uppermost Auch Gleann. 
Reference(s):
In preparation. BGS Sheet Description for Sheet 46W (Crianlarich) and 46E (Killin). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S004