BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327, INSU - CNRS - Institut national des sciences de l'Univers, UO - Université d'Orléans : UMR7327
UO - Université d'Orléans : UMR7327 (Château de la Source - Avenue du Parc Floral - BP 6749 - 45067 Orléans cedex 2 - France)
Abstract : Abstract. Back-arc extension superimposed on mountain belts leads to distributed normal faults and shear zones interacting with magma emplacement within the crust. The composition of granitic magmas emplaced at this stage often involves a large component of crustal melting. The Miocene Aegean granitoids were emplaced in metamorphic core complexes (MCCs) below crustal-scale low-angle normal faults and ductile shear zones. Intrusion processes interact with extension and shear along detachments, from the hot magmatic flow within the pluton root zone to the colder ductile and brittle deformation below and along the detachment. A comparison of the Aegean plutons with the island of Elba MCC in the back-arc region of the Apennine subduction shows that these processes are characteristic of pluton–detachment interactions in general. We discuss a conceptual emplacement model, tested by numerical models. Mafic injections within the partially molten lower crust above the hot asthenosphere trigger the ascent within the core of the MCC of felsic magmas, controlled by the strain localization on persistent crustal-scale shear zones at the top that guide the ascent until the brittle ductile transition. Once the system definitely enters the brittle regime, the detachment and the upper crust are intruded, while new detachments migrate upward and in the direction of shearing.
https://hal-insu.archives-ouvertes.fr/insu-03261912 Contributor : Nathalie PothierConnect in order to contact the contributor Submitted on : Wednesday, June 16, 2021 - 11:08:25 AM Last modification on : Tuesday, May 10, 2022 - 3:25:00 PM Long-term archiving on: : Friday, September 17, 2021 - 6:22:49 PM
Laurent Jolivet, Laurent Arbaret, Laetitia Le Pourhiet, Florent Cheval-Garabédian, Vincent Roche, et al.. Interactions of plutons and detachments: a comparison of Aegean and Tyrrhenian granitoids. Solid Earth, European Geosciences Union, 2021, 12 (6), pp.1357-1388. ⟨10.5194/se-12-1357-2021⟩. ⟨insu-03261912⟩