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Sample 82MW0017, an orthogneiss, contains
K-feldspar (35%), quartz (35%), plagioclase (27%), biotite (1%),
muscovite (1%), and trace oxides and epidote. K-feldspar occurs as
fractured porphyroclasts (fractures are filled by quartz and
plagioclase), and as finer matrix grains. Quartz shows subgrains,
undulose extinction, and some recrystallization with hexagonal grains,
which is also common in matrix plagioclase. Elongated quartz aggregates,
biotite, and muscovite define a foliation that wraps larger K-feldspar
and plagioclase porphyroclasts. Seritization is common in plagioclase. |
