Evolution of peralkaline silicic complexes: Lessons from the extrusive rocks

Young ( 4 wt.%) and the rhyolitic varieties evolve to temperatures < 800 °C at oxygen fugacities largely within the range ∆FMQ 0 to − 1. They can be categorised as of cold-wet-reduced type. Low viscosities (< 104–106 Pa s) result in rapid growth of volcanic edifices, highly efficient crystal–melt separation and the ubiquitous development of compositionally zoned caps to reservoirs. No peralkaline equivalent of the monotonous intermediate ignimbrites found in some calc–alkaline systems has yet been found.