Magmatic flare-up causes crustal thickening at the transition from subduction to continental collision

Carlos E. Ganade , Pierre Lanari , Daniela Rubatto , Joerg Hermann , Roberto F. Weinberg , Miguel A. S. Basei , Lucas R. Tesser , Renaud Caby (1) , Yao Agbossoumondé , Caroline M. Ribeiro

1 Géosciences Montpellier

Above 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 Kabyé Massif, Togo. We show that gabbros intruded 670 million years ago at 20-25 km depth were transformed to eclogites by 620 million years ago at 65-70 km depth. This was coeval with extensive magmatism at 20-40 km 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.

Domains: Sciences of the Universe [physics]

Carlos E. Ganade, Pierre Lanari, Daniela Rubatto, Joerg Hermann, Roberto F. Weinberg, et al.. Magmatic flare-up causes crustal thickening at the transition from subduction to continental collision. Communications Earth & Environment, 2021, 2, ⟨10.1038/s43247-021-00103-z⟩. ⟨insu-03661280⟩