Mj. Daines et Dl. Kohlstedt, THE TRANSITION FROM POROUS TO CHANNELIZED FLOW DUE TO MELT ROCK REACTION DURING MELT MIGRATION/, Geophysical research letters, 21(2), 1994, pp. 145-148
The effect of melt/rock reaction on the mechanisms and kinetics of mel
t migration is investigated through a series of melt migration experim
ents in which melt saturated only in olivine infiltrates synthetic per
idotites containing different proportions of olivine and Ca-poor pyrox
ene. The microstructures that develop are significantly different from
those formed during melt migration in a chemically equilibrated syste
m. A reaction zone develops in which all pyroxene is dissolved, the me
lt fraction is increased, and olivine grain size is increased. The rea
ction front is unstable so that finger-like structures or channels wit
h higher melt content develop. The morphology of the instability depen
ds on the initial pyroxene content of the infiltrated rock. This react
ive-infiltration instability with the resulting formation of melt fing
ers could facilitate the transition from porous to channelized flow in
the mantle.