Origin of felsic sheets in the Scourian granulites: new evidence from rare earth elements

Abstract

Synopsis Felsic sheets within the Scourian granulites of NW Scotland are shown to be granites, trondhjemites and tonalites. Their origin has been extensively debated. Previously they have been considered to be either a product of anatexis of Scourian gneisses during granulite facies metamorphism, or part of a Scourian igneous complex which predated the granulite facies metamorphism. The trace element geochemistry of the felsic sheets is, however, incompatible with an anatectic origin. It is proposed that the felsic sheets were formed by the partial melting of a mafic source at > 15 kbar and that their origin is linked to that of tonalite–trondhjemite–granodiorite suites common in Archaean cratons.