Partially Molten Layer as a Root Zone for Volcanic Activity

Abstract

Partially molten layer, which is expected to exist in the Earth’s upper mantle, is a root zone for magmatic activity. Physical and chemical processes working in this layer set various constraints on this activity. Particularly melt-phase migration process in this layer is a key process which governs the accumulation and the segregation of magma. In Chap. 2, we briefly summarize melt migration process. In Chap. 3, various types of physical properties are reviewed in connection with the melt migration process. Permeability is the most important parameter in controlling the melt migration, although little is known. In Chap. 4, the current picture of partially molten layer is given through various observations. The point emphasized in this review is that the partially molten state is not a simple mixture of liquid and solid. This nature needs essentially new treatment.