Research ArticleGEOLOGY

Multiple episodes of extensive marine anoxia linked to global warming and continental weathering following the latest Permian mass extinction

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Science Advances  11 Apr 2018:
Vol. 4, no. 4, e1602921
DOI: 10.1126/sciadv.1602921
  • Fig. 1 Location of Iran at ~252 Ma ago and geochemical profiles for the Zal section.

    Paleogeographic location of Iran at ~252 Ma [(A) modified after the study of Payne et al. (60)] and geochemical profiles for Zal, Iran (B and C). The 238U/235U ratios are reported in per mil using standard δ-notation, where δ238U = [(238U/235U)sample/(238U/235U)standard(CRM145) − 1] × 1000. δ13C data and stratigraphic column are from Horacek et al. (15) and Richoz et al. (37). With respect to the δ13C profile, C1 to C4 are equivalent to the N1 to N4 negative excursions of Song et al. (19). δ238USW in (B) and (C) denotes δ238U of modern seawater. A representative uncertainty range of 2 SD is shown for the uppermost δ238U data point in (B). (C) Expanded view of the −40- to 40-m interval. Only samples with Mn/Sr < 2.5 are shown. Chang., Changhsingian; Gries., Griesbachian; Smith., Smithian. Following the studies of Clarkson et al. (21) and Martin et al. (44), biozonation of the Zal section is based on ammonoids for the Upper Permian and conodonts for the Lower Triassic. I. isa., Isarcicella isarcica; H. p., Hindeodus parvus; ammonoid zone 3, Pa., Paratirolites; ammonoid zone 2, Dhz., Dhzulfites; ammonoid zone 1, Ph., Phisonites; Ps., Pseudotoceras.

  • Fig. 2 LOWESS curves for δ238U, δ13C, and 87Sr/86Sr profiles of Zal, Iran.

    (A) Uranium isotope (δ238U) profile. (B) Carbon isotope (δ13C) profile (15, 37). δ13C of samples without paired δ238U data are not shown in this figure. (C) Strontium isotope (87Sr/86Sr) profile (38). U-C-Sr isotopes were measured from the same suite of samples. Samples with Mn/Sr > 2.5 have been removed from (A) and (B), and samples with Mn/Sr > 2.5 are indicated with open circles in (C). U. Perm., Upper Permian; Mid. Tr., Middle Triassic; Gries., Griesbachian; Di., Dienerian; Sm., Smithian. Note the change in time scale at 250 Ma.

  • Fig. 3 Marine U-cycle mass balance model, calculated PO43− concentrations, and ammonoid extinction rate curve.

    (A) δ238U data with LOWESS smoothing fit; see the top of figure for legend. (B) Model estimates of anoxic seafloor area (fanoxic) during Late Permian through Early/Middle Triassic time. The red and black lines denote modeling output without and with a diagenetic offset of 0.3‰, respectively. We note that the low δ238U data resolution at the C3 event makes its model estimated timing and extent of oceanic anoxia with larger uncertainties compared to the other events. (C) Calculated PO43− concentrations (conc.) in the Early Triassic ocean. The green and red lines denote modeling output assuming a P/Sr ratio of 0.61 and 0.91, respectively (see the Supplementary Materials). (D) Ammonoid extinction rate curve. See Fig. 2 for stage and substage abbreviations.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/4/e1602921/DC1

    The study section

    Evidence for primary seawater δ238U values

    Compilation of global carbonate δ238U records for PTB interval

    Possible timing of onset of oceanic anoxia

    Age-thickness model for Zal section

    Cross-correlation analysis

    High-resolution intercomparison of Zal δ13C, 87Sr/86Sr, and δ238U records

    Estimation of weathering rates and seawater PO43− levels in the Early Triassic ocean

    Box model estimates for fanox

    Patterns of marine invertebrate clade recovery following the LPME

    Ammonoid extinction rates

    table S1. Strontium and phosphorus model parameterization.

    table S2. Uranium box model parameterization.

    fig. S1. Geochemical profile of Zal, Iran.

    fig. S2. Diagenetic evaluation cross-plots of δ238U-[Sr], δ238U-Mn/Sr, and δ238U-Mg/Ca (mol/mol) of all samples, samples below 3.5 m, samples between 3.5 and 500 m, and samples above 500 m.

    fig. S3. Cross-plots of δ238U-Rb/Sr and δ238U-U/Al ratio [parts per million/weight % (wt %)] for all samples and samples below and above 500 m.

    fig. S4. Cross-plots of δ238U-Mn/Sr, δ238U-Mg/Ca, δ238U-Rb/Sr, and δ238U-U/Al (wt %) for anoxic events 1 and 2.

    fig. S5. Cross-plots of δ238U-Mn/Sr, δ238U-Mg/Ca, δ238U-Rb/Sr, and δ238U-U/Al (wt %) for anoxic events 3 and 4.

    fig. S6. Cross-plots of δ13C-δ18O for the Zal section.

    fig. S7. Location of Iran, South China, and Turkey during the Permian-Triassic transition, ~252 Ma (modified after Payne et al. (60).

    fig. S8. Comparison of U- and C-isotope profiles for Zal, Dawen, Dajiang, Taşkent, and Kamura.

    fig. S9. A LOWESS trend showing inferred timing of onset of latest Permian oceanic anoxia.

    fig. S10. Age-depth model for the Zal, Iran study section.

    fig. S11. Cross-correlation analysis of LOWESS-smoothed curves for U-C-Sr isotope records.

    fig. S12. 87Sr/86Sr-derived estimates of the continental weathering flux and the calculated seawater PO43− concentrations for the Early Triassic ocean.

    fig. S13. Interregional ammonoid zonation scheme.

    dataset S1. δ238U data with associated geochemical data.

    References (61115)

  • Supplementary Materials

    This PDF file includes:

    • The study section
    • Evidence for primary seawater δ238U values
    • Compilation of global carbonate δ238U records for PTB interval
    • Possible timing of onset of oceanic anoxia
    • Age-thickness model for Zal section
    • Cross-correlation analysis
    • High-resolution intercomparison of Zal δ13C, 87Sr/86Sr, and δ238U records
    • Estimation of weathering rates and seawater PO43− levels in the Early Triassic ocean
    • Box model estimates for fanox
    • Patterns of marine invertebrate clade recovery following the LPME
    • Ammonoid extinction rates
    • table S1. Strontium and phosphorus model parameterization.
    • table S2. Uranium box model parameterization.
    • fig. S1. Geochemical profile of Zal, Iran.
    • fig. S2. Diagenetic evaluation cross-plots of δ238U-Sr, δ238U-Mn/Sr, and δ238UMg/ Ca (mol/mol) of all samples, samples below 3.5 m, samples between 3.5 and 500 m, and samples above 500 m.
    • fig. S3. Cross-plots of δ238U-Rb/Sr and δ238U-U/Al ratio parts per million/weight % (wt %) for all samples and samples below and above 500 m.
    • fig. S4. Cross-plots of δ238U-Mn/Sr, δ238U-Mg/Ca, δ238U-Rb/Sr, and δ238U-U/Al (wt %) for anoxic events 1 and 2.
    • fig. S5. Cross-plots of δ238U-Mn/Sr, δ238U-Mg/Ca, δ238U-Rb/Sr, and δ238U-U/Al (wt %) for anoxic events 3 and 4.
    • fig. S6. Cross-plots of δ13C-δ18O for the Zal section.
    • fig. S7. Location of Iran, South China, and Turkey during the Permian-Triassic transition, ~252 Ma (modified after Payne et al. (60).
    • fig. S8. Comparison of U- and C-isotope profiles for Zal, Dawen, Dajiang, Taşkent, and Kamura.
    • fig. S9. A LOWESS trend showing inferred timing of onset of latest Permian oceanic anoxia.
    • fig. S10. Age-depth model for the Zal, Iran study section.
    • fig. S11. Cross-correlation analysis of LOWESS-smoothed curves for U-C-Sr isotope records.
    • fig. S12. 87Sr/86Sr-derived estimates of the continental weathering flux and the calculated seawater PO43− concentrations for the Early Triassic ocean.
    • fig. S13. Interregional ammonoid zonation scheme.
    • References (61–115)

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    Other Supplementary Material for this manuscript includes the following:

    • dataset S1 (Microsoft Excel format). δ238U data with associated geochemical data.

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