ABSTRACT
The oldest primary PGE-Au-U systems generated in the Early Proterozoic on Precambrian shields within intracontinental rifts, were formed on eroded Archean granite-greenstone belts. In the Onega rift (Baltic shield), unique shungite rocks contain associations of U, Au, PGE, V, Mn, Fe, Ni, Co, Bi, Mo, Cu, Cr, Ag, Se and other elements geochemically related to organic carbon. Primary ore-bearing carbonaceous systems were considerably transformed by the intensive decomposition of Corg under the influence initially of Na- and later K-metasomatism. Distributions of aliphatic and polycyclic aromatic hydrocarbons (PAH) were studied in various zones from ore-bearing metasomatites. This study has allowed reconstruction of PGE-Au-U ore-forming processes involving ancient petroleum.
