Abstract

New data are presented that demonstrate the syn-tectonic intrusion of a suite of mafic and ultramafic magmas into the Connemara Dalradian. Magma was intruded during the local D2 episode but immediately prior to the onset of D3. Both deformation episodes affect the gabbros, forming two distinct groups of fabrics formed at different stages during the history of the intrusion. Applying thermal considerations to this history suggest that any gap in time between the formation of these fabrics was <0.5 Ma. The role played by rigid mafic intrusions in influencing the style of deformation is shown and assessed. The Renvyle–Bofin Slide is reinterpreted as an entirely late-tectonic structure related to extension of the Connemara terrane. The implications of a syn-D2/immediately pre-D3 age of emplacement of these bodies for the age of other gabbros in Connemara is discussed. It is suggested that existing tectonic schemes for the area should be modified; either events in Connemara were highly diachronous or the published ages of the gabbros are misleading.

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