The Blokken gneisses: a re-appraisal

Abstract

A group of quartzo-feldspathic gneisses – the Blokken gneisses – is described in the literature as a syn-tectonic igneous suite intruded into the central part of the Nagssugtoqidian mobile belt of South-East Greenland in early Proterozoic time. The gneisses are reported to be transgressive to early structures (Nag. 1) and to show only later (Nag. 2) tectonic fabrics. Field data are at variance with this interpretation. No grounds exist for maintaining the gneisses in question as a distinct unit separable from the regional Archaean gneisses. Consequently the term should be abandoned.