Scientific publications

The results of the geochemical study of the accessory chromites from the Mesoarchean (2.95–2.92 Ga) komatiites from the Sovdozero structure (northern part of the Vedlozero-Segozero greenstone belt) are presented. Several generations of accessory chromites varying in composition from chromohercynite to magnetite were identified in cumulative zones of massive komatiite lava flows (containing 29–34 wt % MgO). Relict grains of primary magmatic chromohercynite – subferrous chromohercynite (Cr2O3 44.21–46.69 %, Al2O3 8.86–13.55 %) crystallized from komatiitic melt in a temperature range of 1260–1340 C were found. The chemical composition of the grains suggests that the primary komatiitic melts of the Al-undepleted type were Ni-enriched. Separation of the ore component from the silicate melt may be the result of deep fractionation of komatiitic magmas through liquid immiscibility.