Two articles by Afifé El Korh and co-authors from Nancy and Villefranche-sur-Mer (France) have been published in Journal of Petrology and Lithos:
The study published in Journal of Petrology (doi: 10.1093/petrology/egz060) investigates lithium mobility and isotope fractionation during the various stages of fluid-rock interactions occurring in the oceanic lithosphere (seafloor and sub-seafloor hydrothermal alteration, subduction and exhumation processes). Li elemental and isotopic compositions were measured in a series of ultrabasic and basic rocks from the Variscan Limousin ophiolite (French Massif Central) and Ile de Groix high-pressure terrane (Brittany, France). In the Limousin ophiolite, high-temperature hydrothermal alteration of oceanic ultrabasic and basic rocks produces serpentinites and amphibolites with low Li abundances. The δ7Li, ranging from negative to positive values, appears to be more sensitive to changes in the fluid composition and temperature conditions. Significant fluid-induced kinetic Li isotope fractionation towards light compositions occurred during prograde subduction zone metamorphism, at the transition from the lawsonite-blueschist facies to the epidote-blueschist facies and under eclogite facies conditions. The results suggest that heavy-Li fluids can migrate in the subduction zone at the interface between oceanic lithosphere and mantle wedge.
The article published in Lithos (doi: 10.1016/j.lithos.2019.105345) examines metallic trace elements in the Limousin ophiolite-derived rocks and granites, in order to determine the behaviour and mobility of the trace elements during fluid-rock interactions related to ophiolite emplacement and post-collision exhumation. The study aims to trace the source of pre-mineralisation concentrations transported by fluids involved in the formation of Variscan ore deposits (including Sn, W, Au and U deposits) in north western French Massif Central.