Importance of compression melting in subduction zones

Abstract

Processes of melt generation in subduction zones are discussed, based on numerical calculations taking account of the flow pattern, energy balance and phase equilibrium constraints for H2O-bearing peridotites. A significant amount of melt is newly found to be produced in the downward flow along the plate by compression melting, corresponding to a gentle or negative dT/dP slope of the solidus curve. The amount of melt produced is comparable to the eruption rate of magmas on volcanic arcs (i.e., 100 to 102 km3/ million year per 1 km of the arc length). Although further studies on the distribution of H2O and melt segregation processes are required for accurate estimates, compression melting in subduction zones is probably inevitable.