Abstract

A schistose metamorphic 'aureole' adjacent to serpentinite is described from 3 localities (Carleton Hill, Knocklaugh farm and Loch Lochton) between the Northern Serpentinite and the Knockormal-Knocklaugh spilites of the Ballantrae Igneous Complex, SW Scotland. Whole-rock and electron microprobe analyses confirm that this c. 40 m thick metamorphic sole essentially comprises a metabasite sequence and that it progrades towards the serpentinite from greenschist to amphibolite-granulite facies. 4 phases of pre-Caradocian deformation are recognized. It is suggested that the sole was formed mainly by tectonic displacement of hot ultramafics against basic rocks. It is likely that this metamorphism developed due to thrusting occurring in a major fault zone initiated within oceanic lithosphere.