A structural cross-section from the Aureole of the Main Donegal Granite

Seven phases of deformation are recognised in Dalradian metasediments within the NW aureole of the Main Donegal Granite. Major NW facing F2 folds (the Aghla Anticline and Errigal Syncline) refold an originally NW facing slaty cleavage, which is usually parallel to bedding. D3 structures cross-cut the major F2 folds and verge and face to the SE on their normal limbs. A fourth phase of deformation intensifies towards the granite contact and is shown to be broadly coeval with intrusion and responsible for a major structure in the aureole. Three later phases are variably developed throughout the aureole. The kinematics of F4 folds in relation to the granite intrusion are briefly discussed.