Lithological and Geochemical Conditions of Sulfur Deposits' Development Over the North Flank of the Zabolotovsk Trough

Results of mineralogical-petrographic and isotope-geochemical investigation of rocks and ores from sulfur deposits over the north flank of the Zabolotovsk trough are presented. A close correlation (n = 0.92) between sigma/sup 34/S and sigma/sup 13/S is established, indicative of a biogenic character of ore mineralization. Calculations show that sulfurous limestones could have been developed in an Upper Tortonian lagoon, as the result of microbiologic sulfate reduction. Products of aerobic methane oxidation probably constituted an additional source of isotope-light biogenic carbon.