Transcrystalline melt migration and Earth's mantle.
Plate tectonics and volcanism involve the formation, migration, and interaction of magma and gas. Experiments show that melt inclusions subjected to a thermal gradient migrate through olivine crystals, under the kinetic control of crystal-melt interface mechanisms. Exsolved gas bubbles remain fixed and eventually separate from the melt. Scaled to thermal gradients in Earth's mantle and geological times, our results account for the grain-scale segregation of primitive melts, reinterpret CO2-rich fluid inclusions as escaped from melt, and question the existence of a free, deeply percolating fluid phase. Melt migration experiments also allow us to quantify crystal growth kinetics at very low undercoolings in conditions appropriate to many natural systems.
Schiano
Pierre
P
Laboratoire Magmas et Volcans, Observatoire de Physique du Globe, Université Blaise Pascal et CNRS, 5 rue Kessler, 63038 Clermont-Ferrand Cedex, France. schiano@opgc.univ-bpclermont.fr
Provost
Ariel
A
Clocchiatti
Roberto
R
Faure
François
F