Oxygen Isotope Constraints on the Sulfur Cycle over the Past 10 Million Years

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Science  26 Mar 2004:
Vol. 303, Issue 5666, pp. 2004-2007
DOI: 10.1126/science.1092296

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Oxygen isotopes in marine sulfate (δ18OSO4) measured in marine barite show variability over the past 10 million years, including a 5per mil decrease during the Plio-Pleistocene, with near-constant values during the Miocene that are slightly enriched over the modern ocean. A numerical model suggests that sea level fluctuations during Plio-Pleistocene glacial cycles affected the sulfur cycle by reducing the area of continental shelves and increasing the oxidative weathering of pyrite. The data also require that sulfate concentrations were 10 to 20% lower in the late Miocene than today.

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