Dynamics of phase fronts in ore-forming fluid systems of volcanic arcs

A mathematical model is proposed to describe the dynamics of phase fronts in volcanogenic orthomagmatic fluid systems (VOFS). It has been shown that these systems require rather short geologic times to reach a quasi-stationary state. This process is accompanied by slow cooling and pressure decrease as the bubbling front within the intrusive body submerges and magmatic fluid discharge decreases. Decompression boiling zone seems to develop in near-surface VOFS part for a certain combination of such parameters as porosity, permeability, and upper boundary condition. In evolving VOFS the existence of this zone is ephemeral. However in areas of seismic tremor and in mixed hydrothermal systems this zone can be stable and can produce brines below the level of hydrotherm discharge.