Specific Features of the Genesis of Manganese Carbonates in the Porozhinsk Deposit (Yenisei Ridge, Krasnoyarsk Region)

The chemical and isotopic compositions of manganese carbonate and oxide ores and host dolomites of the Porozhinsk deposit are studied. Manganese carbonates are characterized by low values of δ 13 C (–19.0 to –8.4‰, PDB) and δ 18 O (8.8 to 27.3‰, SMOW). These data indicate the participation in their formation of the isotopically light carbon from oxidized organic matter, and the water of ore-depositing solutions was most likely meteogenic. The host dolomites (Pod”emsk Formation, Chapa Group) are characterized by a heavier isotopic composition of carbon (2.3‒2.6‰) and oxygen (22.5‒31.3‰) that are typical of marine sedimentary carbonates in the Late Proterozoic sedimentation basin. The simplest organisms played a significant role in the genesis of manganese ores. Microbial structures were preserved in manganese carbonates and oxides.