New data on formation conditions and origin of manganese carbonate ores in the Ulutelyak deposit (Bashkortostan)

The carbon and oxygen isotopic compositions in rocks and ores of the Ulutelyak (Bashkortostan) manganese deposit of the Lower Permian (P₁kg) are studied. Values of ??¹³C, ?? (PDB) and ??¹⁸O, ?? (SMOW) show the following range: from ?3.8 to 3.3 and from 22.0 to 29.6, respectively, in manganese oxide-carbonate ores; from 2.7 to 4.1 and from 28.8 to 29.7, respectively, in non-ore carbonate-clayey interbeds of the ore member; and from 2.8 to 4.5 and from 29.5 to 30.0, respectively, in the underlying and overlying limestones. Lithological features and isotope data suggest that manganese carbonates were formed at the postsedimentary stage of rock transformation due to metasomatic replacement of the primary cyanobacterial sedimentary carbonates by the elisional manganiferous solutions.