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JuryProf. Max COLLINET (UNamur), ChairProf. Johan YANS (UNamur), secretaryProf. Flavien CHOULET (Marie and Louis Pasteur University)Dr. Alexandre FELTEN (UNamur)Prof. Mohammed BOUABDELLAH (Mohammed IV Polytechnic University)Prof. Nadine MATTIELLI (Free University of Brussels)Dr. Augustin DEKONINCK (UMons)AbstractSupergene processes are responsible for the redistribution of metals near the surface and can form economically significant mineral deposits. This PhD thesis investigates the evolution (genesis and timing) of supergene mineralization in polymetallic systems from Morocco (Anti-Atlas and Atlas) and France (Provence). The study combines field observations, petrography, geochemistry, stable isotope analyses, and experimental oxidation to provide a multiscale understanding ranging from microscopic characterization to regional geological evolution.Stable Cu and Fe isotopes show unique fractionation in each deposit, which primarily depends on the primary ore’s isotopic composition. In addition, specific minerals (e.g., arsenates) may strongly influence the Cu fractionation of later-formed minerals (e.g., malachite), which can result in highly variable Cu isotope compositions across deposits. Therefore, Cu and Fe isotopes must be considered site-specific. Experimental investigations complement geological data by quantifying the oxidation rates of pyrite and galena under various conditions. These results highlight that the timing of weathering is reproducible and consistent with natural examples studied in this thesis via (U–Th)/He and K–Ar geochronology. However, pyrite oxidation (4.3 µm/year) is faster than that of galena, which may have a catalytic effect on other sulfides in polymetallic deposits.Overall, supergene mineralization reflects combined controls from mineralogy, host rocks, fluids, climate, and tectonics. This work refines genetic models and provides new tools to describe and constrain secondary mineralization, as well as their potential impact on metallurgical processes.

This is a great recognition of research at UNamur: three Marie Skłodowska-Curie Doctoral Networks (DN) projects have just been awarded, with a key contribution from researchers in Namur! The first, in chemistry, involves Professor Stéphane Vincent; the second, focused on ecosystem resilience, involves Professor Frédérik de Laender; and the third, in the field of photonics, benefits from the expertise of FNRS-qualified researcher Michaël Lobet.