The BGS Lexicon of Named Rock Units — Result Details

Pitlurg Calcareous Flag Formation

Computer Code: PCFL Preferred Map Code: SYMB
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Calcareous, banded psammite and semipelite, grey and pale green, normally flaggy. Some beds of impure metalimestone locally.
Definition of Lower Boundary: At incoming of calcareous (greenish, tremolite-bearing) psammites and semipelites above the non-calcareous Findlater Flag Formation.
Definition of Upper Boundary: Below graphitic pelites with beds of pure metalimestone comprising the Mortlach Graphitic Schist Formation.
Thickness: >50 - 1200m (based on outcrop width and average dip). Real thickness is probably closer to lower estimate, owing to prevalent open folds.
Geographical Limits: Ardonald Anticline, from Blackhillock and Alehousehillock, in the Cairnie area, SW to Achmore, Glen Rinnes. And around Keith from Drummuir to Ardrone (Sheets 85E and 86W). Above Keith Shear Zone - equivalent stratigraphically to Cairnfield Calcareous Formation below the Keith Shear Zone.
Parent Unit: Lochaber Subgroup (DALO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Burn at Davidston from 150m NW of Hillend to 500m N of Bridge at Blairmoon. 
Reference Section  Den of Pitlurg 
Reference(s):
Stephenson, D, et al. 1993. Stratigraphy and correlation of the Dalradian rocks of the East Grampian Project area. British Geological Survey Technical Report WA/93/91. 
Stephenson, D, 1993. Amphiboles from Dalradian Metasedimentary Rocks of NE Scotland: Environmental Inferences and Distinction from Amphiboles of Meta-Igneous Amphibolites. Mineralogy and Petrology, Volume 49, 45-62. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S085 S086