Interaction between mantle-derived magma and lower arc crust: quantitative reactive melt flow modelling using STyx

Published on 2018-04-10T15:25:57Z (GMT) by
The magmatic processes occurring in the lowermost arc crust play a major role in the evolution of mantle-wedge-derived melt. Geological evidence indicates that mantle-derived magmas and <i>in-situ</i> products of lower crust partial melting are reacting in a pervasive melt system and are eventually extracted towards higher levels of the crust. Resolving the relative contribution of mantle-derived magma and partial melting products of pre-existing crust is essential to: (1) quantify crustal growth rate; (2) better understand the compositional range of arc magmatic series; and (3) constrain the chemical differentiation of the lower crust. In this study, we present STyx, a new modelling tool, coupling melt and heat flow with petrology to explore the dynamics of storage, transfer and hybridization of melts in complex liquid/rock systems. We perform three models representing a magmatic event affecting an amphibolitic lower arc crust in order to quantify the relative contribution between partial melting of the pre-existing crust and fractional crystallization from mantle-derived hydrous-magma. Our models demonstrate that most of the differentiated arc crust is juvenile, deriving from the differentiation of mantle melts, and that pre-existing crust does not significantly contribute to the total thickness of magmatic products.

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Riel, Nicolas; Bouilhol, Pierre; van Hunen, Jeroen; Cornet, Julien; Magni, Valentina; Grigorova, Vili; Velic, Mirko (2018): Interaction between mantle-derived magma and lower arc crust: quantitative reactive melt flow modelling using STyx. Geological Society of London. Collection.