The Bothnian coupled oroclines of the Svecofennian Orogen: a Palaeoproterozoic terrane wreck

Abstract

Abstract The accretion of magmatic arcs gives rise to elongate, linear orogens and is a key process in forming new continental crust. Many Precambrian continents are, however, presently equidimensional or have large areas without any clear linearity, such as the central part of the Palaeoproterozoic Svecofennian Orogen (1.92–1.77 Ga). One way of forming an equidimensional continental domain is by buckling of a linear orogen about vertical axes of rotation into one or more coupled oroclines. Here, we reinterpret existing data and demonstrate the occurrence of coupled Bothnian oroclines in the Svecofennian Orogen. Palinspastic restoration of the southern and northern Bothnian oroclines brings a 1000‐km‐long segment of the Svecofennian Orogen into an originally linear, NW ‐striking geometry that restores the lithological belts, metamorphic zones and structural vergences to a common direction, and which indicates that the orogen consists of a SW ‐facing arc, which has been shortened along NE ‐verging folds and thrust faults.