Isotope Compositions (δ13C, δ18O) of Manganese Carbonates of the Porozhinsk Deposit (Yenisei Ridge, Krasnoyarsk Region)

Resumo

New carbon and oxygen isotope data are reported on carbonate ores and host dolomites (upper Pod”emsk subformation) of the Porozhinsk manganese deposit. Manganese carbonates filling the karst depression of the Porozhinsk area are characterized by low δ¹³C (–14.6…–9.5‰, PDB) and δ¹⁸O (18.8…22.1‰, SMOW). These data indicate that the carbonate formation was contributed by the isotopically light carbon, which was released during the decomposition of organic matter, while waters of the ore-precipitating solutions were presumably of meteoric origin. Host dolomites (Porozhinsk and Mokhovoi areas) are characterized by the heavier carbon (–1.9…2.0‰) and oxygen (23.3…27.7‰) isotope compositions, which are presumably typical of carbonate sediments of the Late Neoproterozoic sea basin.