Scientific publications

New geological, geochronological and geochemical data were used for the first time to describe the Ruiga differentiated mafic-ultramafic intrusion located in the north-western part of the Vetreny Poyas paleorift. The intrusion is a typical example of a shallow-depth facies of a peridotite-gabbro-komatiitebasalt association exposed over an area of ca. 20 sq.km. The intrusion falls into three zones totalling up to 810 m in thickness (from the base upwards): pyroxentic, peridotitic and gabbro. Isotopic Sm-Nd age of 2.39 ± 0.05 Ga was obtained for the first time for olivines, pyroxenes, plagioclase and a bulk sample. The age correlates well with the Sm-Nd age (2.44–2.41 Ga) of komatiitic basalts from the Vetreny Poyas suite and the Re-Os ages of lava lake Victoria and Mount Golets (2.39 ± 0.06 and 2.43 ± 0.03 Ga). Based on similar geochemical parameters for the majorelements, trace elements and REE of rocks from the Ruiga intrusion and lava sheets on Mount Golets, they are assumed to have a common deep source. Parent magma, which presumably consisted of Mg-rich komatiitic basalt, suffered differentiation, controlled by the removal of oliline, in intermediate sources in the earth crust. There, it was saturated with crustal matter, and early portions of melts ejected onto the surface were most heavily contaminated with it. The Vetreny Poyas magmatic rocks discussed are correlatable in geological and some geochemical characteristics with the Paleoproterozoic Raglen nickelplatinum metal "komatiitic gabbro-peridotitic complex in Canada".