GMPV1

Formation, evolution and properties of Melts and Magmas: from lab to Nature
Conveners: Max Wilke , Diego Perugini  | Co-Convener: Cristina De Campos 
Oral Programme
 / Tue, 04 May, 08:30–12:00  / Room 20
Poster Programme
 / Attendance Tue, 04 May, 17:30–19:00  / Hall XL
Theme 1: "Silicate Melts, Glasses and Magmas: from lab to Nature": To understand multiphase magma properties, knowledge of the physical, chemical and thermodynamic properties of silicate melts and glasses is required. Furthermore, there is a complex interplay between these properties and both atomic scale structure and dynamics of the melt network and macro-scale behaviour of the bulk magma. Such an interplay dictates the petrologic evolution of magmas and is responsible for the observed geochemical patterns of volatile release and trace element abundances. We strongly encourage the submission of contributions focusing on i) melt/glass thermodynamics with emphasis on mixing properties, ii) spectroscopic evidence for short and medium range structure, iii) the role of cationic and anionic interactions on transport properties, iv) volatile
solubility and diffusivity, v) speciation behaviour of elements, with emphasis on volatiles and trace elements, vi) redox properties and the structural role of transition elements, vii) the glass transition, viii) rheological properties of magmas, with emphasis on both melt and multiphase systems showing complex rheology, ix) experimental and computational determination of phase diagrams, particularly in volatile-bearing systems, and their impact for the study of magma
properties. We also encourage contributions on ab initio modelling of melt thermodynamics and structures and advances in analytical and spectroscopic techniques for glass/melt characterisation, especially in the field of high-pressure research. Finally, applications to both natural magmas and
glasses as well as to industrial processes will be most welcome.

Theme 2: "The Mixing of Magmas from Melt Formation to Eruption": Igneous processes generate compositional gradients at different length scales. Examples include: i) interaction of magmas from variable sources (e.g. mantle and crustal melts); ii) crystallization along walls of magma chambers generating compositional gradients from the centre of the magmatic mass to its peripheral portions; iii) differential assimilation of country rocks in different regions of a magma body; iv) anatexis of heterogeneous rock volumes producing compositional gradients due to different degrees of partial melting. All these processes inevitably trigger mixing episodes and characterize most evolutionary stages of a magmatic system. Furthermore, the embedding geometry where the mixing process may occur (e.g. magma chamber, fracture/channel networks, volcanic conduits) may strongly modulate the fluid-dynamic style and process intensity.
Although increasing natural evidence indicates a major role of magma mixing in igneous systems in all geological environments, several questions still remain open. Among them: what is the smallest length-scale at which magma mixing may generate compositional heterogeneities? What are the most important factors that may promote or inhibit mixing processes? What is the space-time span for generating compositional heterogeneities by magma mixing? How do these heterogeneities may influence the composition of crystallizing minerals and melt inclusions? What are the time scales for hybrid melt production? How can we reconcile these features with classical geochemical models in which both time and space are not taken into account?
The proposed session aims at an interdisciplinary discussion on these and other magma mixing related questions, highlighting its relevance as a petrological and volcanological tool. Contributions documenting the occurrence of magma mixing processes in both plutonic and volcanic environments are welcome, as well as those focusing on experimental, theoretical and numerical modelling.

Solicited Speakers: Alan Whittington, Univ. Missouri, Columbia (USA)