Calendar of Events

Subduction zones play a fundamental role in global geochemical cycles as they recycle oceanic plates including water-bearing sediment, altered igneous crust, and serpentinite into the Earth’s interior. These subducted materials impart their geochemical signatures to the overlying mantle through dehydration and partial melting processes which are ultimately reflected in the compositions of arc magmas worldwide. However, the physical and chemical processes that lead to the transport and mobilization of element and volatile components from the slab to the overlying mantle are poorly understood. The first part of this presentation will focus on a continuum of interrelated mass transfer processes in subduction zones, including (1) fluid-mediated mass transfer between mafic and ultramafic rocks from the high-pressure Voltri Massif (Ligurian Alps, Italy) and the formation of mélange at the slab-mantle interface, and (2) mélange melting and mélange-peridotite interactions in the mantle wedge. I will show that water is a key component in all the processes discussed. Therefore, finding and quantifying water in the Earth’s interior, and illuminating the delivery pathway would refine our understanding of such planetary-scale processes. Deep transport of water down to the mantle transition zone and the uppermost lower mantle is supported by hydrous mineral inclusions in diamonds and geophysical signatures. To explore this further, the second part of this presentation will focus on my proposal to experimentally investigate the fate of oceanic serpentinite as a major carrier of water beyond arcs. Since subducted igneous crust and sediments are expected to undergo extensive dehydration and fluid loss at subarc depths, I hypothesize that the fate and delivery of water to the mantle transition zone and beyond is critically tied to the fate of subducted slab serpentinites due to their high P-T stability.