З.П. Рыбникова, С.А. Светов.
Геохимия акцессорных хромитов из мезоархейских коматиитов Центральной Карелии (на примере Совдозерской структуры)
// Труды КарНЦ РАН. No 1. Сер. Геология Докембрия. 2014. C. 158-166
Z.P. Rybnikova, S.A. Svetov. Geochemistry of accessory chromites in mesoarchean komatiites from Central Karelia (Sovdozero structure) // Transactions of Karelian Research Centre of Russian Academy of Science. No 1. Precambrian geology Series. 2014. Pp. 158-166
Keywords: chromites, komatiites, Mesoarchean, Vedlozero-Segozero greenstone belt, Central Karelia.
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.