Ganade de Araujo, CarlosLanari, PierreRubatto, DanielaHermann, JoergWeinberg, RBasei, Miguel Angelo StippTesser, Lucas RCaby, RenaudAgbossoumonde, YaoRibeiro, Caroline M2023-06-152023-06-152662-4435http://hdl.handle.net/1885/293516Above subduction zones, magma production rate and crustal generation can increase by an order of magnitude during narrow time intervals known as magmatic flare-ups. However, the consequences of these events in the deep arc environment remain poorly understood. Here we use petrological and in-situ zircon dating techniques to investigate the root of a continental arc within the collisional West Gondwana Orogen that is now exposed in the Kabye Massif, Togo. We show that gabbros intruded 670 million years ago at 20-25km depth were transformed to eclogites by 620 million years ago at 65-70km depth. This was coeval with extensive magmatism at 20-40km depth, indicative of a flare-up event which peaked just prior to the subduction of the continental margin. We propose that increased H2O flux from subduction of serpentinized mantle in the hyper-extended margin of the approaching continent was responsible for the increased magma productivity and crustal thickening. Dehydration of serpentinised mantle during subduction of the hyper-extended margin of an approaching continent drove a magmatic flare-up which caused crustal thickening recorded in the Kabye Massif, Togo, according to petrological and geochronological analyses.This research was supported by the Serrapilheira Institute (grant # Serra—1709-21887), Swiss National Science Foundation project N IZESO_l94628 and by the Geological Survey of Brazil. C.E.G. acknowledges the CAPES Higher Education Improvement Coordination 88881.363575/2019-01 for supporting the author’s research visit at the University of Bern. C.E.G and C.M.R thank Julio Cezar Mendes for the help in the EPMA data of sample DKE-380.application/pdfen-AU© The Author(s) 2021https://creativecommons.org/licenses/by/4.0/202110.1038/s43247-021-00103-z2022-04-03Creative Commons Attribution 4.0 International License