THE CALEDONIAN EVOLUTION OF THE LAURENTIAN MARGIN IN WESTERN IRELAND

The Highland Border-Clew Bay-Fair Head- Baie Verte-Brompton Line, whic h probably marks the Laurentian margin, passes through Achill Island i n western Ireland as a zone of ductile transpression within which the Clew Bay Complex and Dalradian Supergroup are juxtaposed. Dextral gree nschist facies transpression fabrics in the Clew Bay Complex record th e northwest directed emplacement of terranes, bearing high P-low T min eral assemblages, against Laurentia, causing the Dalradian continental margin sediments to be thrust westward. There are significant differe nces in timing, structural geometry and regional facing between W Irel and and the Scottish Highland Border Zone.