Island-Arc Augite–Bytownite–Labradorite Dacites of the Kara-Dag Massif, Crimea
Journal: Moscow University Geology Bulletin
Year: 2019

Island-arc calc-alkaline dacites (66.7% SiO2, 3.4% Na2O, 1.9% K2O) form a subvolcanic body hosted within andesitic and trachyandesitic tuffs on the east of the Kara-Dag Volcanic Massif of the Crimean Mountains. These dacites characteristically contain many phenocrysts of plagioclase (bytownite Ca75–72Na24–27K0.5–1 confined to the cores and labradorite Ca67–52Na32–47K1 to the inner and outer rims) and low-Ti augite (augite Ca44Mg45Fe11 with 4.5% Al2O3 confined to the cores and augite Ca43–41Mg41–