Rapid time series  33 S profiles of deep time drill cores by EA combustion techniques Alan J. Kaufman, James Farquhar, and David T. Johnston Department of Geology, University of Maryland Timothy W. Lyons Department of Earth Sciences, University of California, Riverside Gail L. Arnold and Ariel Anbar Department of Geological Sciences, Arizona State University Deep Time Drilling Project of the NASA Astrobiology Drilling Program

EA SO combustion technique Baublys et al. (2004) Rapid Commun. Mass Spectrom. 2004; 18: 2765–2769 He O2O2 vent purge

EA SO combustion technique peak height on m/z 48 up to ~2.0 nA peak height on m/z 50 saturated at ~8E-11 A ~100  g NBS 127 (barite), NZ1, NZ3 interspersed with samples ~100 to 5000  g powdered shale

As elemental Cu in the combustion tube is progressively oxidized there is a correctable drift in the raw sulfur isotope values. EA-CF-SO drift corrections

EA-CF-SO method drift correction run no.  33 S raw  34 S raw  34 S corrwt. %S raw average stdev (1  ) After drift correction, a correction for the interference of 32 S 18 O and 33 S 17 O on 34 S 16 O and for 32 S 17 O on 33 S 16 O is applied (not done by Baublys et al., 2004). This brings the  34 S values into a few tenths of a ‰ consistency of IAEA values.

Hamersley Group stratigraphy in ADBP 9 drill core 100 m 2561 ± 8 Ma 2479 ± 3 Ma

While the total sulfur data conform to ranges defined by CRS analyses from multiple Archean basins, the scatter in this data set may reflect the contribution of organic S in the samples, as well as bacterial processing of sulfur in the oceans.

Conclusions methodology The modified EA-CF-SO technique (using both drift and interference corrections) allows for rapid measurement of S-33 and S-34 abundances in bulk sulfur-rich samples. Corrections are consistent with IAEA values and uncertainties are better than 0.3‰ (1  ) for both  33 S and  34 S compositions. Modifications to the collector array may reduce scattering resulting in even smaller uncertainties. The total sulfur method integrates both organic and sulfide S, so future comparison with CRS will be an important consideration.

Conclusions time series results Bed-to-bed variations in  34 S and  33 S are geologically rapid and are broadly correlated. Scatter in the data greater than the uncertainty of the analyses likely reflects the contribution of organic S (a largely uninvestigated reservoir) as well as bacterial redistribution of mass dependent sulfur isotopes. Rapid variations are likely the result of variable preservation of the atmospheric rain of sulfate (with negative  33 S) and organic S (with positive  33 S), which may be mixed during bacterial pyrite formation. Although the terrestrial input of sulfur to the oceans is considered to be negligible, if seawater sulfate concentrations are low this flux may also have a dilution effect on  33 S values. It is highly unlikely that the rapid variations result from oscillations in atmospheric oxygenation, highlighting the necessity to construct high-resolution time series trends in  33 S through the deep time drill cores. Fe 2+ + H 2 S → FeS + 2H + FeS + S o → FeS 2