Variscan Granites from Brittany

Abstract

From Barrois (1884) to Barrière (1980) it is has been classical to divide Armorican Granites into three main units (Fig. 1): 1. A leucogranite belt which extends from the Pointe du Raz to Bressuire and Parthenay, emplaced during activity on the South Armorican Shear Zone (SASZ, Cogné 1960) and of its subsidiary faults. 2. A red-granite belt which extends along the northern shore of Brittany from Aber Ildut to the Cotentin Peninsula over 300 km in length. In its western part, it is parallel to the Porspoder-Guisseny mylonitic zone (Chauris 1965). 3. Middle-Armorican Batholith, with large elliptic plutons of porphyritic gray granites, extending westwards from the Mancellia Cadomian formations, emplaced during activity on the North Armorican Shear Zone (NASZ, Hirbec 1979).