Final Report Summary - CRITMAG (Critical Behaviour in Magmatic Systems)
The aim of the project was to explore crustal magmatism in terms of the behaviour of a series of interconnected magmatic reservoirs and the implications for the frequency and magnitude of volcanic eruptions. The hypothesis to be tested was that the flux of material between these magmatic reservoirs could lead to the development of critical behaviour in which one or more reservoirs attained the requisite conditions for volcanic eruption. The research team has pursued it objectives through a combination of field geology, high-temperature experiments, microbeam analysis and numerical modelling. These different research strands have been used to address the growing recognition that magmatic systems are crystal-rich (or "mushy") throughout most of their lifetime, challenging the long-held view of magmatic systems as characterised by large vats (or chambers) of dominantly liquid magma. Mushy systems are inherently unstable because of the density difference between solids, melts and gases. This can lead to episodes of instability with relative, but independent, movement of melt and gas through the solid matrix. A major finding has been that the buoyancy of magma relative to the surrounding rocks plays an important role in controlling eruption frequency and magnitude. This has far-reaching consequences for those monitoring restless volcanoes.
Specific achievements include:
Improved tools for deciphering the testimony of volcanic crystals as archives of sub-volcanic processes.
Development of models for the chemical evolution of trans-crustal magmatic mushes
Acquisition of a substantial cumulate rock sample collection from volcanoes of the Lesser Antilles arc as snapshots of the sub-volcanic magma plumbing system
Field studies of a number of recently active volcanoes in a variety of tectonic settings, including the Lesser Antilles, Bolivian Altiplano, Kamchatka, Afar, Mexico and the Cascades.
Providing a framework for the interpretation of rock textures and chemistries in the context of dynamic magmatic mushes.
Specific achievements include:
Improved tools for deciphering the testimony of volcanic crystals as archives of sub-volcanic processes.
Development of models for the chemical evolution of trans-crustal magmatic mushes
Acquisition of a substantial cumulate rock sample collection from volcanoes of the Lesser Antilles arc as snapshots of the sub-volcanic magma plumbing system
Field studies of a number of recently active volcanoes in a variety of tectonic settings, including the Lesser Antilles, Bolivian Altiplano, Kamchatka, Afar, Mexico and the Cascades.
Providing a framework for the interpretation of rock textures and chemistries in the context of dynamic magmatic mushes.