Composition, crystallization conditions and genesis of sulfide-saturated parental melts of olivine-phyric rocks from Kamchatsky Mys (Kamchatka, Russia)

Variations of Source Composition and Melting Degrees of Olivine-Phyric Rocks from Kamchatsky Mys: Results of Geochemical Modeling of Trace Element Contents in Melts

“…1). Trace elements in the olivine from these rocks indicate that their source mineralogical composition corresponds to peridotites (Korneeva et al, 2020), which is typical for the MORB mantle. This fact allows us to suggest that unusual patterns of trace elements distribution in reconstructed melts are linked to chemical heterogeneity of the source and melting degrees.…”

“…All of their key geochemical features and reconstructed crystallization conditions correspond to typical midocean ridge basalts (MORB). An early manifestation of sulfide-silicate saturation was documented in these rocks among other features, which makes them the perfect object for studying the generation and early evolution of oceanic magmas (Korneeva et al, 2020;Savelyev et al, 2018).…”

“…Well-preserved olivine allowed us earlier to reconstruct the composition of parental melts of these plagioclase-olivine-phyric basalts on the base of melt inclusions study (Korneeva et al, 2020). The most interesting features of these parental melts are wide variations of highly incompatible trace elements and relatively low contents of moderately incompatible trace elements (e.g., HREE) in comparison with primitive MORB glasses (Fig.…”

“…In this study we made an attempt to estimate the possible range of melting degrees and source compositions for individual melts of olivine-phyric rocks of Kamchatsky Mys (Korneeva et al, 2020) using different melting mechanisms and variable source compositions for modeling. We showed that trace elements in the majority of these melts can be equally well approximated by models of batch and accumulated fractional melting, while the estimated melting parameters for them can significantly vary depending on the chosen melting mechanism.…”

“…To estimate the compositions of the primary melts of olivine-phyric rocks from Kamchatsky Mys we assumed that they were in equilibrium with typical olivine of MORB mantle peridotites, Fo 90 (e.g., Dick, 1989). We then simulated reverse olivine crystallization using Petrolog3 software (Danyushevsky and Plechov, 2011) for the parental melts of these rocks (Korneeva et al, 2020) until they were in equilibrium with the Fo 90 . Trace elements in melts were accounted as completely incompatible to olivine at this stage of our calculations.…”