Sulfur and carbon isotopic variations in Neoproterozoic sedimentary rocks from southern China
【摘要】:正A new set of δ~(34)S_(sulfide),δ~(34)S_(sulfate)and δ~(13)C_(carbonate)values has been reported from Neoproterozoic sedimentary rocks in southern China.The interglacial black shales of the Datangpo Fm.display higherδ~(34)S_(sulfide)values with+20‰average,but the postglacial black shales from the Doushantuo Fm.show negativeδ~(34)S_(sulfide)values.However,the Jinjiadong Fm.,the same post-glaciation as the Doushantuo Fm.,has positiveδ~(34)S_(sulfide)values,implying that theδ~(34)S value of sedimentary sulfides would be controlled by lithofacies and paleogeographic environments.Theδ~(34)S_(sulfate)values relative toδ~(13)C_(carbonate)were obtained by extraction of trace sulfate from the successive carbonate sequences in the Yangtze Gorges sections.A preliminary interpretation suggests that the oceanic environment may fluctuate dramatically at the post-glacial Doushantuo stage and,then,recover its stability at the Dengying stage on the basis of the high resolutionδ~(34)S andδ~(13)C curves of seawater.