Magma differentiation rates: Combining isotopic constraints and thermal models



Volcanism on the Earth arises due to the partial melting of the upper mantle, which produces magma of basaltic composition. However, most of the compositional variations observed in igneous rocks at any one volcano result from the subsequent processes of magma differentiation, and the dominant process is that of crystal formation and the physical separation of the crystals and the remaining liquid. This process of fractional crystallization leads to gas-rich viscous magmas that have a greater potential to erupt in a catastrophically explosive manner than do more primitive magmas. Volcanologists and geochemists are therefore interested in ways of measuring the differentiation rates of sub-volcanic magmas and in understanding the results in terms of the processes that can cause crystallization.