Crustal recycling and juvenile addition during lithospheric wrenching: The Pontivy-Rostrenen magmatic complex, Armorican Massif (France), Variscan belt

The South Armorican Shear Zone (SASZ), in the French Armorican Variscan belt, is a lithospheric wrench fault that acted during the Late Carboniferous as a transition zone between two distinct domains: a thickened domain to the south affected by extension and crustal magmatism, and a weakly thickened domain to the north subjected to dextral wrenching and crust- and mantle-derived magmatism. The Pontivy-Rostrenen complex is a composite intrusion emplaced along the SASZ. To the south, the complex is made of leucogranites whereas, to the north, monzogranites outcrop together with small intrusions of quartz monzodiorite. U-Pb dating of magmatic zircon by LA-ICP-MS reveal that most magmatic rocks were emplaced at ca. 315Ma (between 316.7±2.5Ma and 310.3±4.7Ma), excepted a late leucogranitic intrusion that was emplaced at 304.7±2.7Ma. The leucogranites (−4.8