Magma Mixing in Igneous Systems

Since the first hypothesis, evidences of magma mixing processes have been accumulated in the literature allowing this natural phaenomenon to be defined as fundamental petrological processes playing a role in activating volcanic eruptions and generating compositional variability in igneous systems. Here, we review the key concepts to provide the best understanding of the physical and chemical processes occurring during magma mixing. In particular: 1) an historical perspective, recounting the discovery and evolution of our understanding of magma mixing through time; 2) definitions of mixing and mingling and their major geological evidence from the field; 3) scaling rules and numerical modelling, with a deep overview on the kinematics of magma mixing; 4) a synopsis of experimental investigations of the complexity of magma mixing processes; 5) the implications of magma mixing in volcanic systems together with highlights, outstanding issues and possible future developments.