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): Glenelly Formation (A) [Obsolete Code: Use GLLY] (DCGG)
Glenelly Formation (B) [Obsolete Code: Use GLLY] (DCGO)
Glenelly Formation [Obsolete Code: Use GLLY] (-932)
Tourmaline Schists Of Glenelly North (-284)
Alternative Name(s): none recorded or not applicable
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. 
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: