Devolatilization During Subduction

Experimental constraints on formation of hematite in olivine at high pressures and temperatures

“…Additionally, a wave speed reduction in 25 % in the Tonga-Fiji subducting plate (Savage 2012) translates to 60 % serpentinization. At relatively shallow depths (<6 GPa), H 2 O in the subducting slab may be transferred to the overlying mantle wedge through melts or fluids when slab geotherms pass through the serpentine-out reaction boundary (Schmidt and Poli 2014). At greater depths, the experimental results of this study indicate that hydrogen released from the subducting slab could be another source of volatile components transferred to the overlying mantle wedge.…”

Mineralogy of the Earth: Phase Transitions and Mineralogy of the Upper Mantle

“…At these conditions, the H 2 O content of the rock was estimated to be around 6 wt.% (Schmidt and Poli, 2014). At these conditions, the H 2 O content of the rock was estimated to be around 6 wt.% (Schmidt and Poli, 2014).…”

Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet

“…Combined with their high Pb/Ce and Ba/La ratios (both Pb and Ba are fluid mobile) (Figures c and d), it is likely that the formation of Nariniya samples was influenced by the input of “slab‐derived fluids” (e.g., Chan et al, ; Chen et al, ; Li et al, ; Teng et al, ). In subduction zone, fluids can be released by either sediments or low‐temperature seafloor altered basalts due to increased temperature and pressure (Schmidt & Poli, ). However, sediments carried by subducted Songpan‐Ganzi slab are clay‐rich and would produce fluids with high Li concentration (>300 ppm) and low δ 7 Li values (−0.80‰, at 450 °C) (Simons et al, ), which would shift the δ 7 Li of Nariniya samples toward lower values, opposite to the observed high δ 7 Li values.…”