Research ArticleGEOCHEMISTRY

Strong local, not global, controls on marine pyrite sulfur isotopes

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Science Advances  26 Feb 2021:
Vol. 7, no. 9, eabb7403
DOI: 10.1126/sciadv.abb7403
  • Fig. 1 Location of studied boreholes.

    (A) IODP 1352: 44.9374°S; 172.022692°W and ODP 1123: 41.786°S; 171.499°W. Also shown are the bathymetry (depth contours in meters) and the deep Pacific inflows; the ACC and the DWBC. Redrawn from (27). (B) Simplified stratigraphy of studied boreholes with corresponding lithological units. Age-calibrated stratigraphic correlations from this study are shown in Ma. MP, regional Marshall Paraconformity; E, Eocene.

  • Fig. 2 Divergent stratigraphic Δpyr records.

    Shelf and deep basin Δpyr values (red and blue, respectively, this study) over the past 40 Ma. Filled markers have strong stratigraphic age constraints (foraminiferal δ18O measurements), whereas empty markers have less robust age constraints (biostratigraphic and/or magnetostratigraphic tie points). For global climatic context, deep-sea records of δ18O [light gray circles and dark line; (34, 40)] are shown. Note the change of scale of δ18O associated with the change of time scale between the middle and rightmost parts of the figure, as represented with the inner gray y axis on the right.

  • Fig. 3 Strong sea-level control.

    (A) Relationship between change in sea level (m relative to present day) and Δpyr values. The green band represents the theoretical equilibrium sulfate-sulfide sulfur isotope fractionation (ΔSO4-H2S) at the bottom-water temperature of the study sites (43). Filled markers have strong stratigraphic age constraints (foraminiferal δ18O measurements), whereas empty markers have less robust age constraints (biostratigraphic and/or magnetostratigraphic tie points). (B) Box and whisker plots of Δpyr values grouped by systems tract associated with fourth-order sea-level variation. Red horizontal lines denote the median; the box upper and lower boundaries denote the 75th and 25th percentiles of the data, respectively; and the black horizontal lines contain 99.3% of the data. Data include only samples with strong stratigraphic age constraints (i.e., 0 to 1.9 Ma). HST, highstand systems tract; LST, lowstand systems tract; TST, transgressive systems tract.

Supplementary Materials

  • Supplementary Materials

    Strong local, not global, controls on marine pyrite sulfur isotopes

    V. Pasquier, R. N. Bryant, D. A. Fike, I. Halevy

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