Séminaire George Bergantz

Title : The Magic of Magma (Mush)

Abstract:

Magmatic systems are now understood be dominated by crystal-rich mushy conditions, yet the kinematics and dynamics of magma mush are poorly understood. They are not generally elastic media, nor a sponge, nor a dirty fluid, nor amenable to treatment as a simply-connected continuum. It is a loose endoskeleton, sitting in a pool of silicic melt, and both contribute to the unique behaviors that are recorded in natural examples. In this presentation we will review the unique and fascinating physics of hydrogranular systems and apply those to geological examples of mush unlocking, mixing, shear zone formation, magmatic fabrics and so on. The key piece of physical logic is the notion of a granular force chain, and we will explore how this allows for a new understanding of how failure is defined and propagates as a cascade through the granular network from the micro to the macro scale.