The BGS Lexicon of Named Rock Units — Result Details

Aonach Beag Semipelite Formation

Computer Code: AOBG Preferred Map Code: AB
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Schistose semipelite and micaceous psammite with white quartzite beds locally abundant in the type area.
Definition of Lower Boundary: Boundary between platy feldspathic psammites of the Inverlair Psammite Formation and schistose micaceous psammites and semipelites. Base where micaceous psammite and semipelite become dominant.
Definition of Upper Boundary: Transitional boundary into overlying Kinlochlaggan Quartzite Formation marked by either increasing psammite in locally increasing proportion of interbanded quartzite. Top at point where quartzite becomes dominant.
Thickness: Generally to 200m but c.500m in the Aonach Beag area.
Geographical Limits: Ardverikie Forest, southern Central Highlands of Scotland, largely on sheet 63E [Dalwhinnie].
Parent Unit: Appin Group (APP)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  NW ridge of Aonach Beag and western side of Coire na Coichille. 
Reference Section  Coire an Iubhair Mor on upper north-east flank of Geal Charn. 
Reference Section  Allt Liath nam Badan - burn section. 
Reference(s):
Robertson, S and Mendum, J R, in press. Lithostratigraphy of the Grampian and Appin Groups in the Dalwhinnie district, sheet 63E, Scotland. British Geological Survey Technical Report. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S063 S063