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3.9 Magma physics

The complex, multiphase nature of natural magmatic systems has generated the need for the investigation of complex geomaterials. Magma Physics is thus concerned with the physical properties of composite geomaterials as well as the nature and efficiency of the physical interactions between phases in magmas during fractionation processes. Such processes range from segregation of melt from partially molten source rocks to degassing and fragmentation of volcanic edifices. Specific areas of recent investigation include deformation mechanisms in partially molten systems, the role of convection in magma chambers, the kinetics of crystal-melt equilibration and the degassing and fragmentation of highly viscous melts.

The laboratory contribution to these investigations often involves 1) the design of specialized experimental facilities dedicated to the solution of individual problems in the field of magma physics and 2) the careful microscopic and submicroscopic physical and chemical characterisation of experimental geomaterials before and after experiments are performed. Only with such a wholistic approach to the experimental investigation of the physics of magmatic processes can progress be made towards reliable predictions.

The physics of magmatism is influenced to the greatest extent by the highly non-linear nature of the variation of bulk magma properties arising from the physical mixture of solid and liquid phases. This is most acutely felt in the description of the deformation of magmas. The relative efficiency and importance of Newtonian versus non-Newtonian flow and brittle versus ductile deformation in 1) the segregation of melts from their source regions, 2) the fractionation of phases during magma evolution and 3) the nature of the petrogenetic products of these complex evolving magmatic systems as plutonic or volcanic igneous rocks and juvenile fluids is poorly known. The experimental investigation of a sufficiently wide range of conditions of temperature, pressure, strain rate, sample chemistry and physical state is a task that will require a sustained intermediate to long term commitment. Such studies must also be carefully linked to the growing body of knowledge on melt physics and chemistry as well as the increasing understanding of the links between these properties and their structural and dynamical origins.

Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
Tel: +49-(0) 921 55 3700 / 3766, Fax: +49-(0) 921 55 3769, E-mail: bayerisches.geoinstitut(at)