Malyi Zadoi peridotite-gabbronorite massif: computational modeling of crystallization and evaluation of indicator geochemical parameters of parental melt

Model calculations have been used to estimate the compositions of melts during the fractional crystallization corresponding to the formation of the Malyi Zadoi massif, which is located in the Irkut block of the Sharyzhalgai uplift in the southwest of the Siberian craton. It is shown that the gabbronorites of the massif are comagmatic to plagioperidotites and olivine gabbronorites. The obtained estimates of the composition of the model melts are used to characterize the composition of the mantle source for parental melt. Based on the obtained geochemical characteristics, it is assumed that the parental melt of the Malyi Zadoi massif was formed by the melting of an enriched source, which is confirmed by isotope data. A possible source of parental melt could be the depleted lithospheric mantle metasomatized by felsic melts from the rocks of the subducting oceanic plate.