Metasedimentary rocks, associated intrusions and tectonic features of the Precambrian in eastern Bamble, South Norway: an interpretative study.

Abstract

Based on the results of mapping programmes and map compilation work carried out by the author in recent years, a subdivision of the bedrock geology of the easternmost part of the Bamble Sector into two domains is proposed - the Kragerø and Portør domains, separated by a major fault zone. These domains shows contrasting sedimentary and magmatic histories, particularly in theirearlier phases. In the Portør domain, a large, elongate body of diorite to granodiorite is identified but not yet dated isotopically. It has no equivalent in the Kragerø domain where the Levang Granite Gneiss Dome (LGGD) is a dominatedn feature. The latter is assessed in terms of synplutonism and its relationship to adjacent metasedimentary rocks and their fold patters. The significance of existing isotopic age data in relation to field data is also considered. The existense of an early developed through or half-graben into which clastic sediments of the Kragerø domain were deposited is envisaged.