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3.6 Melt Physics and Chemistry

Tackling questions from magma generation and ascent to the formation and properties of the core revolves around our understanding of molten systems. A variety of projects, which are described below, have taken a multitude of approaches, but all have concentrated on linking structure and properties of melts as a way to constrain models being developed to describe the condition and processes that are influenced by the presence of melts in Earth's interior. Beginning from a theoretical basis, vibrational properties of glasses as understood from the calculation of Raman spectra are linked to the distribution of bridging and non-bridging oxygens in the glass. From carefully controlled experiments at 1 atm, melt properties such as viscosity and element partitioning can be correlated to compositional parameters that influence melt polymerization and other structural characteristics. Volumetric measurements are shown to provide an alternative means of evaluating the influence of pressure on melt properties. The role played by water in melts has continually demanded our attention, and universal models are now seemingly within grasp. Finally, we have continued to expand the frontier of melt physics and chemistry with new high pressure and high temperature investigations, which have now become the manner of choice only a few short years after an era of what can be considered mainly as glass science.

Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany
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