Subduction zones modulate the chemical evolution of the Earth’s mantle. Water and volatile elements in the slab are released as fluids into the mantle wedge and this process is widely considered to result in the oxidation of the sub-arc mantle. However, the chemical composition and speciation of these fluids remain poorly constrained. Here I reconstruct the petrological evolution of serpentinites in the Western Alps, recognized as a natural laboratory to study fluid transfers during subduction. I determine the evolution of iron redox state in these rocks during prograde metamorphism and then try to decipher the nature of slab derived fluids combining Fe redox measurements (XANES) with Fe stable isotopes.
About the speaker:
I am a permanent researcher employed by the Centre National de la Recherche Scientifique (CNRS) and working at the Université de Paris - Institut de Physique du Globe de Paris. I completed my PhD in metamorphic petrology at the Laboratoire Magmas & Volcans (France, 2010 - 2014). Subsequently, I held several postdoctoral research associate positions in England for three years, first at Durham University and then at the University of Cambridge. I then moved to the Université Libre de Bruxelles to take up a 3-year fellowship postdoctoral position funded by the “Fond National de la Recherche Scientifique” until October 2019, when I took up my current position at the French CNRS. My work concerns the cycling of iron (Fe), sulfur (S), carbon (C) and economically important elements, such as Zn and Cu, during fluid/rock interactions between the hydrosphere and the oceanic crust at mid-oceanic ridges and between the deep Earth, the continental crust and the surface in subduction zones. I am particularly interested in the processes that control redox sensitive elements mobility in fluids.