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Isotopic compositions of Mn-carbonate and organic carbon from the same individual samples and sulfur isotopic compositions of pyrites in the basal Datangpo Formation were analyzed. Highly 34S-enriched pyrites (d34Spyrite=31.7-59.4‰) were precipitated in rel- atively occlusive pore water under anoxic condition in sediments, which is consistent with the observation of large and scattered pyrite framboids. The sulfidic deep ocean was not “oxidized” in the early Datangpo interglacial interval, thus the level of seawater sulfate remained low and marine d34Ssulphate remained high. Low d13Ccar (average 7.4‰) and abnormal relationship between d13Ccar and frac-tionation (Dcar-org) imply that the negative d13Ccar excursion may have resulted from oxidation of part of a large organic carbon reser-voir. High Dcar-org (average 25.1‰) implicates high CO2 level in the atmosphere. Small standard deviation (1.0‰) of d13Ccar values indicates the Mn-carbonate was precipitated near the water-sediment interface under dysoxic conditions rather than in occlusive pore water in sediments.
Isotopic compositions of Mn-carbonate and organic carbon from the same individual samples and sulfur isotopic compositions of pyrites in the basal Datang formation were analyzed. Highly 34S-enriched pyrites (d34Spyrite = 31.7-59.4 ‰) were precipitated in rel- atively occlusive pore water under anoxic condition in sediments, which is consistent with the observation of large and scattered pyrite framboids. The sulfidic deep ocean was not “oxidized” in the early Datangpo interglacial interval, thus the level of seawater sulfate remained low and marine d34Ssulphate remaining high . Low d13Ccar (average 7.4 ‰) and abnormal relationship between d13Ccar and frac-tionation (Dcar-org) imply that the negative d13Ccar excursion may have resulted from oxidation of part of a large organic carbon reser- voir. High Dcar-org 25.1 ‰) implicates high CO2 level in the atmosphere. Small standard deviation (1.0 ‰) of d13Ccar values indicates the Mn-carbonate was precipitated near the water-sediment ment interface under dysoxic conditions rather than in occlusive pore water in sediments.