Mardi 29 novembre
Cristina do Campos Prof au Dept. for Earth and Environmental Sciences, Ludwig-Maximilias-Universität München
donnera un Séminaire de Géochimie-frontières Géosciences à 16 H dans l’amphi de Cuvier, 1 rue Jussieu.
Magma mixing and its implication for the evolution of natural magmas: from nature to experiments.
Differentiation processes may generate compositional gradients in magmas at different length scales. Some examples are: i) interaction of magmas produced by different sources and/or different partial melting degrees (e.g. mantle and crustal melts); ii) crystallization along walls generating compositional gradients from the center towards the periphery
of a magma body; iii) differential assimilation of country rocks; iv) differential anatexis producing compositional gradients. All these processes inevitably trigger mixing in the involved systems. This characterizes any stage of the life span of a magmatic system.
What are the main parameters controlling the mixing process in natural silicate melts? What is the role of the local geometry (e.g. magma chamber, fracture/channel networks, volcanic conduits) in the fluid-dynamic style and intensity of the process?
In order to approach these questions we started observing nature (e.g. the architecture of natural frozen-in magma chambers) and then simulate the mixing process in the lab. For this purpose we use as end-members, or starting materials, mostly natural melts. Our aim is to contribute to unraveling the complexity of magma mixing by combining the principles of fluid dynamics with the chemical evolution of the system in time.