Mardi 15 Septembre 2015, à 14h en salle Jean Jung
Titre du séminaire : Dégazage volcanique du manteau à la surface ; effet sur le mouvement, la chimie et la structure moléculaire du magma
Title: Volcanic degassing from mantle to surface; effect on magma motion, chemistry and molecular structure
Department of Earth Sciences, University of Cambridge, United Kingdom
In this seminar we will explore how the degassing of volatile elements affects the chemistry, molecular structure and physical properties of a magma. The presentation will showcase three recent studies; in the first one we’ll look at the effect of persistent degassing on magma motion showing how convection in volcanic conduit and magma chambers can be sustained by the influx of volatiles. In the second study we’ll look at the effect of degassing on the oxidation state of a magma, in particular showing the key role of sulphur. Finally we’ll delve into kimberlite melts which can contain up to 40 wt.% of volatiles. We’ll look at the very unconventional solubility behaviour of volatile species in kimberlite melts and at the effect of degassing on their molecular structure, physical properties and ascent dynamics.