Density of hydrous magma

Magmas in the interior of the Earth have been geophysically observed. The generation of magmas is closely related to H2O because the water-induced decrease in the melting temperature of mantle rocks is an essential process, which forms hydrous magmas due to H2O incorporation into the molten rocks. Knowledge on physical properties of hydrous magmas, such as density, can give us better understanding of the magma behavior inside the Earth. The density of hydrous magma can be controlled by the partial molar volume of H2O (V¯H2O) and its pressure- and temperature-dependences. The new compression behavior of V¯H2O using Vinet equation of state is proposed based on compiled data. Since H2O is one of the most compressible oxides in the magma at lower pressure, a rapid densification of hydrous magma can be observed at shallower mantle. The dense hydrous magma can be gravitational stable above and below mantle transition zone.