Scientific publications

The Onega trough is a post-rift continental depression produced by destruction of the Sumian rift arc during subsequent activation and cooling of an asthenolith. The trough has been existing since the Upper Jatulian as a closed continental basin with an 800 m thick evaporitic formation at the base. In Ludicovian time, it was succeeded by carbonateterrigenous-carbonaceous and trapp formations. The accumulation of reduced forms of carbon in unique quantities and volcanism are interrelated. Plutonic magmatism with differentiated intrusive sheets of Fe-, Ti-, V-, Cu-, Au-, Pt- and Pd-enriched ferrodolerites manifests itself at the flanks of the depression. Their age, 1983–1984 Ma, is similar to that of Pechenga nickeliferous ferrodolerites. The chemical and mineral composition of the subvolcanic phase of Ludicovian volcanics is described, and a REE distribution pattern in Onega trough trapps is shown. Comparative analysis of the structural and magmatic characteristics of the Onega and Norilsk-Kharaelakh depressions has led the authors to conclude that the Onega Ore Province is likely to host a high Cu-Ni Norilsk-type magmatically generated mineralization.