Multiple sulphur isotopes reflecting atmospheric and oceanic evolution in the Archean and Paleoproterozoic
Final Report Abstract
Sulfur is ubiquitous in the environment and participates in inorganic as well as microbially driven processes. Moreover, sulfur is being cycled on Earth under low- as well as high-temperature conditions. The discovery of mass-independent sulfur isotopic fractionation resulting from UV-induced photochemical processing of volcanogenic sulfur dioxide in an essentially oxygen-free atmosphere (<10^-5 PAL, i.e. present day atmospheric level) and archived in Archean and early Paleoproterozoic sedimentary rocks (>2.4 Ga) has revolutionized the interest in sulfur isotope geochemistry. Numerous details of an emerging multiple sulfur isotope record are presently worked out, but a clear relationship between atmospheric composition (e.g., related to O2 abundance, to CH4 abundance, to the SO2/H2S ratio) and the magnitude in mass-independent sulfur isotope fractionation is discernible from the rock record. Hence, this analytical approach has yielded a valuable proxy for reconstructing the composition and evolution of the ancient atmosphere. But it is not only the application towards the early part of Earth’s history. The analytical improvements that allow the simultaneous measurement of all four stable sulfur isotopes has motivated researchers to apply the multiple sulfur isotope approach to numerous geological and biological questions that are – in principle – characterized by mass-dependent isotope fractionation. The discovery of small, yet statistically significant differences in the ratio between the four stable sulfur isotopes has triggered an increasing number of applications in earth and life sciences in order to understand and/or better constrain environmental conditions. Respective questions include the distinction between low- and high-temperature processes and the distinction between inorganic versus biologically driven processes in basic and applied research.
Publications
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(2011) Hydrothermalism in the Tyrrhenian Sea: inorganic and microbial sulfur cycling as revealed by geochemical and multiple sulfur isotope data. Chemical Geology 280: 217-231
Peters, M., Strauss, H., Petersen, S., Kummer, N., Thomazo, C.
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(2012) Sulphur diagenesis in the sediments of the Kiel Bight, SW Baltic Sea, as reflected by multiple sulfur isotopes. Isotopes in Environmental and Health Studies 48: 166-179
Strauss, H., Bast, R., Cording, A., Diekrup, D., Fugmann, A., Garbe-Schönberg, D., Lutter, A., Oeser, M., Rabe, K., Reinke, D., Teichert, B.M.A., Westernströer, U.
