r by the flating ofplagioclase crystals within the magma chamber and (2) the so-called anorthosite massifs, plutons typically containing plagioclase that is andesine orlabradorite (An35-65)' The former are somewhat better understood, the Anorthosite Series in the upper portion of the Critical Zone of the BushveldIgneous Complex being an excellent example. They develop by gravitystratifiation in ultramafi to mafi complexes, ar characterized by rhythmiclayering, show many cumulate textures, are free of megacrysts, are nottypically sheared, and are composed mostly of plagioclase in the An70-100range (Herz, 1976).
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