The BGS Lexicon of Named Rock Units — Result Details

Glenelly Formation

Computer Code: GLLY Preferred Map Code: GY
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Mixed series of quartz feldspar psammites and semi pelitic biotite schists with tourmaline.
Definition of Lower Boundary: Conformable with Dart Formation.
Definition of Upper Boundary: Conformable with Glengawna Formation.
Thickness: at least 2.7km
Geographical Limits: Sperrin Mountains, counties Tyrone and south Londonderry, Northern Ireland.
Parent Unit: Argyll Group (ARGY)
Previous Name(s): Tourmaline Schists Of Glenelly North (-284)
Glenelly Formation [Obsolete Code: Use GLLY] (-932)
Glenelly Formation (A) [Obsolete Code: Use GLLY] (DCGG)
Glenelly Formation (B) [Obsolete Code: Use GLLY] (DCGO)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Top of formation. First conspicuous graphitic mica schist in Glengawna Formation, in Glendarragh Burn, Glenlark. 
Partial Type Section  Bottom of formation. Oughtboy Burn, transition from medium-grained gritty psammites and graphitic mica schists (Dart Formation) to silvery green semi-pelitic, schistose flags with tourmaline and albite. 
Reference(s):
Hartley, J J, 1938. The Dalradian rocks of the Sperrin Mountains and adjacent areas in Northern Ireland. Proceedings of the Royal Irish Academy, Vol.XLIV, section B, 141-171. 
Arthurs, J W, 1976. The geology and metalliferous mineral potential of the Sperrin Mountains area. Geological Survey of Northern Ireland, Special Report No.1, 119pp, 2app, 2 figs, 7 tables, 102 maps. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
N26