Reconnaissance studies of gneisses, ultrabasites, eclogites and anorthosites in Outer Nordfjord, Western Norway.

Abstract

A reconnaissance map of the geology of Outer Nordfjord is presented with some new structural and petrographic data. Mesoscopic folds have often steep axes or curved axial planes which indicate rather plastic type of deformation, but the macroscopically recognizable folding of the area has axes with a rether constant gentle plunge towards E or between E and NE. Older linear structures are present in the area around Måløy while younger movements are reflected in EW folds and dislocations along EW lines. The dominating rock of the area is a biotite-rich banded gneiss of granodioritic composition with zones of pelitic gneiss, quartz-mica-schist and feldspathic quartzite. Other important gneiss types are augen gneiss, granitic gneiss and mangeritic rocks. Ultrabasites, eclogites and anorthosites (or their altered derivatives) are common as inclusion in the gneisses, while gabbros do not occur. All genisses, except the mangeritic rocks, are interpreted as original supracrustal rocks. The biotite-rich banded gneisses with associated pelitic gneiss and quartz-mica-schist are probably essentially isochemically metamorphosed greywackes or volcanites.