In igneous petrology, the compositional trend of plagioclase feldspar (from calcium-rich to sodium-rich, i.e. the plagioclase solid-solution / Bowen's continuous reaction series) tracks the overall evolution of a magma from mafic toward more felsic compositions.
Anorthosite is a rock dominated by calcic plagioclase (often bytownite to labradorite composition), reflecting its association with more primitive, mafic magmatic systems. Granodiorite, being a...
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