Partial melting

Melting of only part of a rock; the melt and remaining solid generally have different compositions.

Chemical modification of residual rock by extraction of melt. In mantle peridotite, depletion commonly changes mineral proportions and trace-element contents, and can accompany volatile loss. Compositional buoyancy and water content must be assessed separately from thermal density changes when explaining a long-lived craton.

Concentration of melt transport toward a narrower extraction zone, affecting how melt production is converted into oceanic crust thickness.

The proportion of material present as geological melt, with a mass or volume convention specified.

Melting during ascent when a hot rock parcel crosses its solidus as pressure falls, without requiring external heating of the ascending parcel.

Melting induced by addition of components, especially water, that lower a rock’s solidus.