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Published in:
2016 | OriginalPaper | Chapter
Progressive Melting of a Metasedimentary Sequence: the Saint-Malo Migmatitic Complex, France
Authors : Vojtěch Janoušek, Jean-François Moyen, Hervé Martin, Vojtěch Erban, Colin Farrow
Published in: Geochemical Modelling of Igneous Processes – Principles And Recipes in R Language
Publisher: Springer Berlin Heidelberg
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This chapter shows a worked example, modelling the crustal anatexis to form a migmatitic complex. Starting with geological and petrological data, we describe the main geochemical features of the lavas and model their evolution. In this environment, the melts are not well extracted from their solid residue. They are poorly homogenised and their composition largely reflects the variations of the particular source lithologies. Fortunately, field relations allow to directly constrain the local melt amount. Increasing melt fractions correspond to successive melting reactions, and thus a residue with an evolving composition. We propose, therefore, a strategy based on describing the evolution of melt’s composition for a given source as a function of the melt amount (and therefore of the nature of the residue), and of the source’s composition. Finally, we bracket the possible range of melts between the compositions derived from two end-member sources.