Parental magmas of Grenville Province massif-type anorthosites, and conjectures about why massif anorthosites are restricted to the Proterozoic
Published:October 01, 2010
Jean H. Bédard, 2010. "Parental magmas of Grenville Province massif-type anorthosites, and conjectures about why massif anorthosites are restricted to the Proterozoic", Sixth Hutton Symposium on The Origin of Granites and Related Rocks: Proceedings of a Symposium held in Stellenbosch, South Africa, 2- 6 July 2007, John D. Clemens, Colin Donaldson, Carol D. Frost, Alexander F.M. Kisters, Jean-François Moyen, Tracy Rushmer, Gary Stevens
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Trace element inversion modelling of Grenvillean anorthosite massifs and associated rocks yield NMORB-normalised trace element profiles enriched in highly incompatible elements; commonly with negative Nb and Th anomalies. Model melts can be divided into subtypes that cannot be linked through fractional crystallisation processes. Most model melts are depleted in the heavy rare-earth elements and can be explained by partial melting of arc basaltic sources (5–60 melting %) with garnet-bearing residues. Some of the model melts have flat NMORB-normalised profiles (for rare-earth elements), have high compatible element contents, and might have been derived from mantle fertilised by arc magmatism, followed by...