CRITMAG · Critical Behaviour in Magmatic Systems

Crustal magmatism is periodic on a very wide range of timescales from pulses of continental crustal growth, through formation of granite batholiths, to eruptions from individual volcanic centres. The cause of this periodicity is not understood. I aim to address this long-standing geological problem through a combination of experiments, petrological methods and numerical models via a novel proposal that periodicity arises because of the highly non-linear ( critical ) behaviour of magma crystallinity with temperature in a series of linked crustal magma reservoirs. The ultimate objective is to answer five fundamental questions: Why is crustal magmatism episodic? " How are large batholiths formed of rather similar magmas over long periods of time? " How do large bodies of eruptible magma develop that can lead to huge, caldera-forming eruptions? " What controls the chemistry of crustal magmas? Why are some compositions over-represented relative to others? " What is the thermal structure beneath volcanic arcs and how does it evolve with time? The project will address these questions through case studies of three contrasted active volcanoes: Nevado de Toluca, Mexico