Short Paper: Evidence for a ‘Grenville’ event in the Lewisian of the northern Outer Hebrides

Abstract

Northern Britain lay between two areas of major tectonic activity in the late Proterozoic but evidence for geological events of this age within Britain are sparse. Twenty five new Rb–Sr biotite ages from a 50 km traverse through the northern Outer Hebrides show that a block, bounded in the south by the Langavat Shear Zone, was generally uniformly affected by an event close to 1.1 Ga. Consideration of the age pattern on either side of the Langavat Belt suggests that there were kilometre-scale displacements on this shear zone at that time, involving uplift and erosion of the northern Outer Hebrides as a whole. It is thus possible that the northern Outer Hebrides acted as a source area for both Laxfordian and ‘Grenville’ detritus found in the Torridonian.