| Abstract: | In connection with the imbalance between the carbon dioxide absorbed in the carbonate minerals in subduction zones and that
emitted during island arc volcanism, the problem of redistribution the rest of the CO2 from the plate to the mantle arises. Experimental modeling of the interaction between model analogs of the oceanic crust
and the mantle wedge was performed for two systems: glaucophane schist-olivine and glaucophane schist-silicate marble-olivine
under high pressure and varying temperature conditions that correspond to the oceanic crust-mantle transition zone in the
subduction zone beneath the Cascade Mountains. The experiments carried out showed that there is a possibility that intensive
CO2 degassing occurs from the plate in the forearc area, which is controlled by carbonate dissolution in an aqueous fluid. As
a result of this process, carbonates can redeposit in the form of magnesite in the overlying mantle rocks according to the
vertical temperature gradient. It is assumed that part of the carbon dioxide bonded in mantle rocks can be transported by
viscous flow from the forearc area to the deep mantle horizons within the field of the thermodynamic stability of magnesite.
In addition, the experiments we carried out showed that between marble and olivine in the ultrahigh pressure a metasomatic
column consisting of four zones develops: Fe-Mg-Ca carbonate|dolomite|diopside|magnesite. |
