Paleomagnetism of the Belomorian Mobile Belt: integrated studies and geodynamic consequences

Detailed petro-paleomagnetic studies of the Early Paleoproterozoic metagabbroids of the Belomorian Mobile Belt (Province) were carried out between 67° and 63° N. Two metachronous magnetization components were distinguished in the medium-temperature (up to 450 °C) and high-temperature (450–580 °C) intervals. The high-temperature component was identified in almost all objects. In the northern part, this component is pointed to WSW and down. It has a ‘banana’ distribution in every object, indicating chemical remagnetization. The main magnetic-carrier mineral is magnetite, ‘encapsulated’ in quartz. The paleomagnetic poles recalculated from this component are close to the paleomagnetic poles of 2.1 Ga for the Kola block. In the southern part of the Belomorian Province, the WNW declination naturally changes to NNE. The paleomagnetic poles are close to the 1.98–1.90 Ga poles for the Karelian Craton. Thus, rocks of the Belomorian Province acquired the high-temperature component during the continental subduction. We revealed a trend for ‘rejuvenation’ of the high-temperature component from NW to SE. The different directions of the high-temperature component in different parts of the Belomorian Province indicate the time of exhumation of individual tectonic blocks. The thermoviscous medium-temperature component demonstrates a NW direction and downward inclination. It has a clustered distribution for all objects. This component has the same average direction as the ‘Svecofennian remagnetization’ for the Karelian Craton. It was formed at the final collisional stage of the Belomorian Province formation at ca 1.86 Ga.