Tracing of evolution of carbonatite and silicate melts of the Belo-Ziminsky alkaline-ultrabasic carbonatite massif by mineralogy and geochemistry

The Belo-Ziminsky alkaline-ultrabasic carbonatite massif contain dolomite, and calcite ankerite carbonatites essential part , syenites, melteigites and iolites cut by aillikite dikes of several generations (Ashchepkov et al., 2020; Doroshkevich et al., 2014-2021 etc). We analyzed  >4000 mineral grains by electron microscope in all types of rocks and >230 grains by  LA ICP MA  All rocks of the massif are derived from one type of mantle melt that was close to aillikite and formed at a level of >5 GPa in the mantle.

According to the nature of the PGE spectra –  and by serpentinized xenoliths in aillikites, this melt drained metasomatized enriched peorvskites and hydrogenated mantle and was initially very rich in HFSE. Above, at the level of the crust and the upper part of the mantle, the melt began to separate under liquation. In the lower and middle crust, several (3) magmatic chambers were probably formed sequentially, which separated various carbonate and silicate melts, and from dolomite to ankerite melts, judging by the slope, the number of grains in the source decreased, that is, the melts became less deep and more fractionated.

These trends are reflected both in the composition of pyroxenes from aillikites  and in the PTX diagram . All this led to significant variations in rocks and their rare-earth spectra of all rocks