Island-arc augite-bytownite-labradoritic dacites of the Kara-Dag, Crimea
Journal: Moscow University Bulletin Series 4 Geology
Year: 2019

Island-arc calc-alcaline dacites (66,7% of SiO 2 , 3,4% of Na 2 O, 1,9% of K 2 O) compose a subvolcanic body among tuffs, andesites and trachyandesites in the east of the Kara-Dag volcanic massif of the Rocky Crimea. The unique features of dacites is abundance of plagioclase phenocrysts (the central zone is bytownite Ca 75–72 Na 24–27 K 0,5–1 ; the intermediate and external zones is labradorite Ca 67–52 Na 32–47 K 1 ) and low-Ti augite (augite Ca 43–41 Mg 41–38 Fe 16–21 with 1–2% of Al 2 O 3 com