Séminaire ISTeP - Marco Scambelluri

(Gênes, prof. invité ISTeP)

Petrological and geochemical role of serpentinite in subduction zones and plate interface domains

Serpentine minerals and serpentinites trigger major tectonic and geochemical processes in Earth. Their abundance in oceanic plates and in subduction zones controls the water budgets and the properties of slabs and overlying mantle. Great importance is now given to interface domains between subducting and overlying plates, where serpentinite either forms kilometre-thick layers generated by hydration of supra-subduction mantle, or occurs in tectonic mélanges atop the slab.
In such environments, serpentinite controls deformation channelling, fluid release and mass transfer. Release of trace element-rich fluids from slab to mantle is dictated by serpentinite stability and by it ‘spongy’ behavior in storing water, carbon and fluid-mobile elements.
Here I discuss what is recorded by several serpentinized mantle occurrences in the Alps in terms of fluid storage and release, and of geochemical signature of fluids and rocks. Goal is achieving constraints on element recycling in subduction zones, as well as on provenance and tectonic accretion of serpentinized materials to plate interface settings.

02/10/2014 à 12h30, Salle Fourcade (Tour 55/56, 4ème étage)