ИСТИНА

We present the geochemical profiles across the olivine phenocrysts in four different magmatic regimes at Kamchatka: (a) maars and tuff rings, (b) monogenetic cones, (c) dikes formation, and (d) lavas of stratovolcanoes. Each volcanic-magmatic regime is characterized by their specific olivine zoning history, size and shape of the crystals, ascending and residence times. Time scales were estimated by Ni-Mg/Fe diffusion modeling of zoning in olivine crystal cores and outer rims by quantitative geochemical profiles. Modeling is based on the analytical solution of diffusion equation to approximate measured geochemical profiles and estimates for P and T from Al-in-olivine thermometry and Cpx-melt barometry.