The Connemara Eastern Boundary Fault: A review and assessment using new evidence

Abstract:The boundary between the Carboniferous sedimentary rocks and the igneous and metamorphic rocks of the Connemara basement between Galway and Oughterard has been described, either all or in part, as an unconformity or a fault known as the Oughterard Fault. We present new data on the geology of this boundary. A significant faulted contact in the Moycullen area is described for the first time and integrated with other new and existing data to form a reassessment of the nature of the boundary. Arguments for the presence of a fault or unconformity are posited. It is concluded that the whole length of the boundary is faulted. Finally, an exploration of possible extensions to the boundary fault is presented. It is suggested that the fault zone could extend southwards into the Gort Lowlands, and, at the northern end, it may be linked to the Maam Valley Faults.