The BGS Lexicon of Named Rock Units — Result Details

Lagan Mor Formation

Computer Code: LAMO Preferred Map Code: SYMB
Status Code: Full
Age range: Tonian Period (AT) — Tonian Period (AT)
Lithological Description: Near base: feldspathic psammite and pelite interbedded (5-20 cm scale); siliceous psammite to quartzite interbedded on dm scale with subordinate dark pelite layers; near top pelite with subordinate psammite interbedded on cm scale, with increase of strain.
Definition of Lower Boundary: Conformably upon the Upper Shiaba Psammite Formation (USHP). Transitional boundary, marked by gradual increase of semipelitic beds.
Definition of Upper Boundary: Structually overlain by the Scoor Pelite Formation (Glenfinnan Group), but separated by a shearzone with intense mylonitisation.
Thickness: none recorded or not applicable
Geographical Limits: Ross of Mull, Isle of Mull, Inner Hebrides.
Parent Unit: Morar Group (MORR)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Coastal section on Ross of Mull, Traigh Bhan na Sgurra [NM 424 183 - NM 423 188]. 
Reference(s):
Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. 
Krabbendam M, Strachan R A, Prave A. 2021. A new stratigraphic framework for the early Neoproterozoic successions of Scotland. Journal of the Geological Society of London. doi:10.1144/jgs2021-054 
Holdsworth, R E, Harris, A L and Roberts, A M, 1987. The stratigraphy, structure and regional significance of the marine rocks of Mull, Argyllshire, west Scotland, Geological Journal, Vol.22, 83-107. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S043