Pentevrian and brioverian in the North armorican massif : characteristics and geodynamic evolution
Résumé
The North Armorican Massif is one of the rare areas within the Hercynian belt of Western Europe where the Precambrian basement outcrops. Within this basement, two main cycles may be distinguish (1) The Pentevrian or Icartian (2.2 - 1.8 Ga) composed of metamorphic rocks mainly derived from magmatic protoliths. (2) The Brioverian which stratigraphic correlations are not perfectly established. The numerous plutons emplaced during this period allow a chronology of the main tectonometamorphic events to be established.
Nowadays, the Late Precambrian evolution (660 Ma - 540 Ma) of the North Armorican domain is interpreted as resulting from a subduction geodynamic process, but the vergence of the subduction remains a matter for discussion. Nevertheless, most of the major structures now visible in this domain are related to this Precambrian History.
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