Fundamental subdivisions of Precambrian granitoids in the Åmål mega-unit and the evolution of the south-western Baltic Shield, Sweden

Abstract

The “Åmål-Kroppefjäll granites” have hitherto been regarded as belonging to the “Gothian orogeny” of southern Scandinavia and have been considered equivalent to the Småland-Värmland granites of south-eastern Sweden. In the Åmål-Kroppefjäll region there actually occur several groups of granitoid intrusives of widely different ages and lithotectonic characteristics. The good state of preservation of the rocks in this region is due to its synclinorial subsidence during and after a major event of regional metamorphism and migmatization affecting much of south-western Scandinavia. It is concluded that the concept of a single coherent development of the “Åmål-Kroppefjäll granites” and the previously suggested correlations and definitions of the “Gothian” in southern Scandinavia are untenable.