High-temperature centrifuge simulation- new method to study multiphase flow of partially molten zones

Abstract

Present-day physical theories suggest that the mantle was partially or completely molten about 4.5 billion years ago. As is expected, the phase separation could result in the stratification of the initially homogeneous mantle into reservoirs of different chemical composition. Because of the poor knowledge of the physical phenomena connected with the multiphase system differentiation, many aspects of the evolution of partially molten zones remain disputable. In this study the simulation of liquid and crystal separation in a hightemperature centrifuge was carried out. Experimental simulation with the pyroxene + olivine + plagioclase + magnetite + melt mixture demonstrates the gravitational instability of the polycrystalline framework of partially molten zones. The melt motion in partially molten rocks is though to be a multiphase flow involving both the melt and individual crystals. A high mobility of plagioclase crystals in the multiphase flow was ascertained. It is revealed as the formation of a monomineral plagioclase cumulate overlying the accumulated molten layer. The separation and motion of sulfides in the intercrystalline space is shown to be in an intimate relationship with the degree of melting of a silicate material.