The Precambrian crystalline complex of south-western Sweden: The geology and petrogenetic development of the Varberg region. A reply

Abstract

Although interpretations of complex gneissic regions lacking systematic mapping and age determination are necessarily speculative, they are not necessarily valueless. Basement-cover relationships and structures following intensive reworking are largely predictable. Their apparent complexity should not therefore inhibit attempts at identification and distinction of the disparate elements, as seems possible, for instance, at Varberg, Orust and, perhaps, Åmål. Whilst the imprint of Sveconorwegian—Dalslandian activity on southwestern Sweden is not denied, it is believed that the major characters of the gneiss belt were determined by and, in the main, still reflect a distinctive constructive cycle intermediate between the Svecofennian and Sveconorwegian. Ensialic supracrustal deposits of unknown areal extent were incorporated with their basement in the tectono-thermal activity of this period. This involved intense basement re-activation with widespread introduction of granitoid elements to the meta-cover sequences. A stage of late, intense, post-tectonic recrystallisation is characteristic. The Hästefjorden and Bohus granite events may be successive stages in a regeneration of activity with a more northerly focus. If the old terms “Gothian” and “Gothian Cycle” were suitably redefined, they would provide a more apposite terminology than “Hallandian”, a locally defined term which would become redundant or restricted in its use.