Isotope disequilibrium studies and magmatic processes

Subsurface crystallisation and degassing significantly influence the evolution and eruption of magmas. Both processes are inevitable consequences of the residence of magma in shallow reservoirs, and both obscure the nature of the pristine liquids derived from the melting region. However, the signatures of crystallisation and degassing, and the very act of being stored, can be recognized under suitable conditions in the signature of the various decay-chain products of the isotopes 238U and 232Th. The isotopic disequilibrium patterns of very young magmas have the potential of allowing geologists to quantify the characteristic timescales of magmatic crystallisation, storage and degassing. -from Autho