The Stratigraphy and Structure of the Errigal Area, County Donegal, Ireland

The Dalradian rocks of the Errigal area form part of the envelope of the Donegal granites. The sedimentary succession established in the adjacent Creeslough district by McCall (1955) is traced to the south-west, where eleven stratigraphical divisions, consisting of quartzites, banded quartzites, pelites, and limestones, amount to a thickness of at least 14,000 feet. The major structure in the area is a recumbent syncline; extensive sliding along the normal limb of this fold has removed up to 6000 feet of strata. The axial trend is variable, and bending has caused subsidiary cross-folding and shearing. Accompanying the emplacement of granite bodies, minor structures and thermal metamorphism were superimposed on the regional fabric developed during the major folding. A detailed picture of the behaviour of these various structures is provided by an analysis of the minor elements.