Biotites and associated minerals as markers of magmatic fractionation and deuteric
equilibration in granites.
Additional processes like liquid immiscibility and deuteric
alteration probably played only a minor role in crystallization, and are therefore omitted.
Minh Tien offers an example of a so-called hybrid pegmatite in which part of the early assemblage has somehow survived the customary deuteric
Albite, as complete pseudomorphs after magmatic plagioclase (albite I), is lacking in the deuteric
assemblages commonly observed in the unaffected granite.
The content of Fe is relatively low, although clearly higher than that in typical deuteric
muscovite (Speer 1987).
Mineralogy, textures and chemistry suggest that some magma mixing and/or deuteric
alteration may have taken place within the complex.
Occasionally amphibole--as deuteric
alteration --is present.