Sulfur isotope geochemistry and the end Permian mass extinction

The use of carbonate associated sulfate (CAS) to study sulfur isotope chemostratigraphy is investigated in detail. Results suggest that middle-shelf limestones are better suited for sulfur isotopic analysis than proximal evaporites or dolostones because of possible facies-related factors that preclude the latter phases from recording true seawater sulfate delta34S values. Carbonate samples with pyrite should be avoided because of evidence of pyrite oxidation during the CAS extraction process.; Coupled sulfur and carbon isotopic fluctuations associated with the end Permian mass extinction in Turkey suggest that the mass extinction was caused by H2S and CO2 resulting from shallow-water euxinia following a prolonged period of deep ocean anoxia in the Late Permian. Extensive deposition of evaporites during the Permian may have contributed to the global anoxia by burying the oxidized form of sulfur as sulfate. Extreme volcanism from the Siberian Traps may have expanded the deep-ocean euxinia into the shallow ocean, where toxic levels of H2S and CO2 may have been introduced to the atmosphere.; Following the mass extinction, elevated delta34S values throughout the entire Early Triassic suggest that anoxia continued for at least five million years after the end Permian mass extinction. However, the relegation of lithologic features characteristic of anoxia to deeper-water environments of deposition suggest that the anoxia was once again restricted to the deep ocean following the end Permian mass extinction.