Formation of magmatic titanite and titanite–ilmenite phase relations during granite alteration in the Tribeč Mountains, Western Carpathians, Slovakia

摘要: Abstract In this study, formation of titanite, in Carboniferous I-type granites/granitoids from the Tribec Mountains (Slovakia), and its subsequent alteration products are described. Titanite occurs early magmatic differentiates granites/granitoids. Calculation model mineral equilibria system K 2 O–CaO–FeO–Al O 3 –TiO –SiO –H O–O (KCFATSHO) indicates that titanite forms as a consequence reaction between titanomagnetite, biotite, anorthite fluid-rich environment under relatively oxidizing conditions, during later stages magma crystallisation. Evidence for can be found low temperature inclusions Ti-rich magnetite biotite well not only interstitially, but also locally quartz. The process has lead to complete replacement by ilmenite, quartz, REE-bearing epidote, allanite while preserving characteristic euhedral, diamond shape former titanite. Completely altered grains become optically opaque due presence ilmenite. epidote is probably release REE alteration. This explained hydration reactions such titanite + anorthite + annite + H O = ilmenite + clinozoisite + muscovite + quartz. involving precursor minerals, plagioclase indicate ilmenite requires an influx H and/or increase f . with highest degree strongly mylonitized granite, which rock-forming minerals have been replaced sericite, chlorite. breakdown common phenomenon some granites southwest area Mountains, indicating widespread late-stage fluid activity, associated high subsolidus cooling.