The second pulse of the Late Ordovician mass extinction occurred around the Hirnantian-Rhuddanian boundary (~444 Ma) and has been correlated with expanded marine anoxia lasting into the earliest Silurian. Characterization of the Hirnantian ocean anoxic event has focused on the onset of anoxia, with global reconstructions based on carbonate δ238U modeling. However, there have been limited attempts to quantify uncertainty in metal isotope mass balance approaches. Here, we probabilistically evaluate coupled metal isotopes and sedimentary archives to increase constraint. We present iron speciation, metal concentration, δ98Mo and δ238U measurements of Rhuddanian black shales from the Murzuq Basin, Libya. We evaluate these data (and published carbonate δ238U data) with a coupled stochastic mass balance model. Combined statistical analysis of metal isotopes and sedimentary sinks provides uncertainty-bounded constraints on the intensity of Hirnantian-Rhuddanian euxinia. This work extends the duration of anoxia to >3 Myrs - notably longer than well-studied Mesozoic ocean anoxic events.

Department of Geology and Geophysics Yale University New Haven CT 06511 USA

Faculty of Environmental Sciences Czech University of Life Sciences Prague Prague Czech Republic

School of Earth and Atmospheric Sciences Georgia Institute of Technology Atlanta GA 30332 USA

School of the Environment Geography and Geosciences University of Portsmouth Portsmouth PO1 3QL UK

Stanford University Department of Geological Sciences Stanford CA 94305 USA

Zobrazit více v PubMed

Finnegan S, et al. The magnitude and duration of late Ordovician-Early Silurian glaciation. Science. 2011;331:903–906. doi: 10.1126/science.1200803. PubMed DOI

Harper DAT, Hammarlund EU, Rasmussen CMØ. End Ordovician extinctions: a coincidence of causes. Gondwana Res. 2014;25:1294–1307. doi: 10.1016/j.gr.2012.12.021. DOI

Rasmussen CMØ, Kröger B, Nielsen ML, Colmenar J. Cascading trend of early Paleozoic marine radiations paused by late Ordovician extinctions. Proc. Natl Acad. Sci. USA. 2019;116:7207–7213. doi: 10.1073/pnas.1821123116. PubMed DOI PMC

Rasmussen CMØ, Kröger B, Franeck F, Rasmussen CMØ. The evolutionary dynamics of the early Palaeozoic marine biodiversity accumulation. Proc. R. Soc. B Biol. Sci. 2019;286:20191634. doi: 10.1098/rspb.2019.1634. PubMed DOI PMC

Finnegan S, Rasmussen CMØ, Harper DAT. Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction. Proc. R. Soc. B Biol. Sci. 2016;283:20160007. doi: 10.1098/rspb.2016.0007. PubMed DOI PMC

Hammarlund EU, et al. A sulfidic driver for the end-Ordovician mass extinction. Earth Planet. Sci. Lett. 2012;331–332:128–139. doi: 10.1016/j.epsl.2012.02.024. DOI

Zou C, et al. Ocean euxinia and climate change ‘double whammy’ drove the Late Ordovician mass extinction. Geology. 2018;46:535–538. doi: 10.1130/G40121.1. DOI

Bartlett R, et al. Abrupt global-ocean anoxia during the Late Ordovician–early Silurian detected using uranium isotopes of marine carbonates. Proc. Natl Acad. Sci. USA. 2018;115:5896–5901. doi: 10.1073/pnas.1802438115. PubMed DOI PMC

Crampton JS, Cooper RA, Sadler PM, Foote M. Greenhouse-icehouse transition in the Late Ordovician marks a step change in extinction regime in the marine plankton. Proc. Natl Acad. Sci. USA. 2016;113:1498–1503. doi: 10.1073/pnas.1519092113. PubMed DOI PMC

Crampton JS, et al. Pacing of Paleozoic macroevolutionary rates by Milankovitch grand cycles. Proc. Natl Acad. Sci. 2018;115:5686–5691. doi: 10.1073/pnas.1714342115. PubMed DOI PMC

Darroch SAF, Wagner PJ. Response of beta diversity to pulses of Ordovician-Silurian mass extinction. Ecology. 2015;96:532–549. doi: 10.1890/14-1061.1. PubMed DOI

Huang B, Jin J, Rong JY. Post-extinction diversification patterns of brachiopods in the early–middle Llandovery, Silurian. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2018;493:11–19. doi: 10.1016/j.palaeo.2017.12.025. DOI

Melchin MJ, Mitchell CE, Holmden C, Storch P. Environmental changes in the late Ordovician-early Silurian: review and new insights from black shales and nitrogen isotopes. Geol. Soc. Am. Bull. 2013;125:1635–1670. doi: 10.1130/B30812.1. DOI

Klemme HD, Ulmishek GF. Effective petroleum source rocks of the world: stratigraphic, distribution and controlling depositional factors. Am. Assoc. Pet. Geol. Bull. 1991;75:1809–1851.

Page A, Williams M, Zalasiewicz J. Were transgressive black shales a negative feedback mechanism modulating glacio-eustatic cycles in the early Palaeozoic Icehouse? Micropalaeontol. Soc. Spec. Publ. Geol. Soc. Lond. 2007;8:123–156.

Pohl A, Donnadieu Y, Le Hir G, Ferreira D. The climatic significance of late Ordovician-early Silurian black shales. Paleoceanography. 2017;32:397–423. doi: 10.1002/2016PA003064. DOI

Ghienn JF, Kröger B, et al. A Cenozoic-style scenario for the end-Ordovician glaciation. Nat. Commun. 2014;5:4485. doi: 10.1038/ncomms5485. PubMed DOI PMC

Sperling EA, et al. Statistical analysis of iron geochemical data suggests limited late Proterozoic oxygenation. Nature. 2015;523:451–454. doi: 10.1038/nature14589. PubMed DOI

Gilleaudeau GJ, et al. Uranium isotope evidence for limited euxinia in mid-Proterozoic oceans. Earth Planet. Sci. Lett. 2019;521:150–157. doi: 10.1016/j.epsl.2019.06.012. DOI

Lau KV, Macdonald FA, Maher K, Payne JL. Uranium isotope evidence for temporary ocean oxygenation in the aftermath of the Sturtian Snowball Earth. Earth Planet. Sci. Lett. 2017;458:282–292. doi: 10.1016/j.epsl.2016.10.043. DOI

Loydell DK. Graptolite biostratigraphy of the E1-NC174 core, Rhuddanian (lower Llandovery, Silurian), Murzuq Basin (Libya) Bull. Geosci. 2011;84:651–660.

Loydell DK. Graptolite biozone correlation charts. Geol. Mag. 2012;149:124–132. doi: 10.1017/S0016756811000513. DOI

Gradstein, F. M. et al. The Geologic Time Scale 2012. Elsevier 1, (2012).

Lüning S, Craig J, Loydell DK, Štorch P, Fitches B. Lower Silurian ‘hot shales’ in North Africa and Arabia: regional distribution and depositional model. Earth Sci. Rev. 2000;49:121–200. doi: 10.1016/S0012-8252(99)00060-4. DOI

Loydell DK, Butcher A, Frýda J. The middle Rhuddanian (lower Silurian) ‘hot’ shale of North Africa and Arabia: an atypical hydrocarbon source rock. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2013;386:233–256. doi: 10.1016/j.palaeo.2013.05.027. DOI

Butcher A. Chitinozoans from the middle Rhuddanian (lower Llandovery, Silurian) ‘hot’ shale in the E1-NC174 core, Murzuq Basin, SW Libya. Rev. Palaeobot. Palynol. 2013;198:62–91. doi: 10.1016/j.revpalbo.2012.11.009. DOI

Dahl TW, et al. Devonian rise in atmospheric oxygen correlated to the radiations of terrestrial plants and large predatory fish. Proc. Natl. Acad. Sci. USA. 2010;107:17911–17915. doi: 10.1073/pnas.1011287107. PubMed DOI PMC

Kendall B, et al. Uranium and molybdenum isotope evidence for an episode of widespread ocean oxygenation during the late Ediacaran Period. Geochim. Cosmochim. Acta. 2015;156:173–193. doi: 10.1016/j.gca.2015.02.025. DOI

Lau KV, et al. Marine anoxia and delayed Earth system recovery after the end-Permian extinction. Proc. Natl Acad. Sci. USA. 2016;113:2360–2365. doi: 10.1073/pnas.1515080113. PubMed DOI PMC

Andersen MB, Stirling CH, Weyer S. Uranium isotope fractionation. Rev. Mineral. Geochem. 2017;82:799–850. doi: 10.2138/rmg.2017.82.19. DOI

Kendall B, Dahl TW, Anbar AD. The stable isotope geochemistry of molybdenum. Rev. Mineral. Geochem. 2017;82:683–732. doi: 10.2138/rmg.2017.82.16. DOI

Miller CA, Peucker-Ehrenbrink B, Walker BD, Marcantonio F. Re-assessing the surface cycling of molybdenum and rhenium. Geochim. Cosmochim. Acta. 2011;75:7146–7179. doi: 10.1016/j.gca.2011.09.005. DOI

Dahl TW, et al. Uranium isotopes distinguish two geochemically distinct stages during the later Cambrian SPICE event. Earth Planet. Sci. Lett. 2014;401:313–326. doi: 10.1016/j.epsl.2014.05.043. PubMed DOI PMC

Tribovillard N, Algeo TJ, Lyons T, Riboulleau A. Trace metals as paleoredox and paleoproductivity proxies: an update. Chem. Geol. 2006;232:12–32. doi: 10.1016/j.chemgeo.2006.02.012. DOI

Neubert N, Nägler TF, Böttcher ME. Sulfidity controls molybdenum isotope fractionation into euxinic sediments: evidence from the modern Black Sea. Geology. 2008;36:775–778. doi: 10.1130/G24959A.1. DOI

Reinhard CT, et al. Proterozoic ocean redox and biogeochemical stasis. Proc. Natl Acad. Sci. USA. 2013;110:5357–5362. doi: 10.1073/pnas.1208622110. PubMed DOI PMC

Morford JL, Emerson S. The geochemistry of redox sensitive trace metals in sediments. Geochim. Cosmochim. Acta. 1999;63:1735–1750. doi: 10.1016/S0016-7037(99)00126-X. DOI

Dunk RM, Mills RA, Jenkins WJ. A reevaluation of the oceanic uranium budget for the Holocene. Chem. Geol. 2002;190:45–67. doi: 10.1016/S0009-2541(02)00110-9. DOI

Poulton SW, Canfield DE. Ferruginous conditions: a dominant feature of the ocean through Earth’s history. Elements. 2011;7:107–112. doi: 10.2113/gselements.7.2.107. DOI

Stylo M, et al. Uranium isotopes fingerprint biotic reduction. Proc. Natl Acad. Sci. USA. 2015;112:5619–5624. doi: 10.1073/pnas.1421841112. PubMed DOI PMC

Bone SE, Dynes JJ, Cliff J, Bargar JR. Uranium(IV) adsorption by natural organic matter in anoxic sediments. Proc. Natl Acad. Sci. USA. 2017;114:711–716. doi: 10.1073/pnas.1611918114. PubMed DOI PMC

McManus J, et al. Molybdenum and uranium geochemistry in continental margin sediments: paleoproxy potential. Geochim. Cosmochim. Acta. 2006;70:4643–4662. doi: 10.1016/j.gca.2006.06.1564. DOI

Scott C, Lyons TW. Contrasting molybdenum cycling and isotopic properties in euxinic versus non-euxinic sediments and sedimentary rocks: Refining the paleoproxies. Chem. Geol. 2012;324–325:19–27. doi: 10.1016/j.chemgeo.2012.05.012. DOI

Weyer S, et al. Natural fractionation of 238U/235U. Geochim. Cosmochim. Acta. 2008;72:345–359. doi: 10.1016/j.gca.2007.11.012. DOI

Algeo TJ, Tribovillard N. Environmental analysis of paleoceanographic systems based on molybdenum-uranium covariation. Chem. Geol. 2009;268:211–225. doi: 10.1016/j.chemgeo.2009.09.001. DOI

Rasmussen CMØ, Algeo TJ, Lyons TW. Mo-total organic carbon covariation in modern anoxic marine environments: implications for analysis of paleoredox and paleohydrographic conditions. Paleoceanography. 2006;21:PA1016.

Nägler TF, Neubert N, Böttcher ME, Dellwig O, Schnetger B. Molybdenum isotope fractionation in pelagic euxinia: Evidence from the modern Black and Baltic Seas. Chem. Geol. 2011;289:1–11. doi: 10.1016/j.chemgeo.2011.07.001. DOI

Romaniello SJ, Herrmann AD, Anbar AD. Uranium concentrations and 238U/235U isotope ratios in modern carbonates from the Bahamas: assessing a novel paleoredox proxy. Chem. Geol. 2013;362:305–316. doi: 10.1016/j.chemgeo.2013.10.002. DOI

Jenkyns HC. Geochemistry of oceanic anoxic events. Geochem. Geophys. Geosyst. 2010;11:Q03004. doi: 10.1029/2009GC002788. DOI

Ostrander CM, Owens JD, Nielsen SG. Constraining the rate of oceanic deoxygenation leading up to a Cretaceous Oceanic anoxic event (OAE-2: ∼94 Ma) Sci. Adv. 2017;3:e1701020. doi: 10.1126/sciadv.1701020. PubMed DOI PMC

Zhang F, et al. Multiple episodes of extensive marine anoxia linked to global warming and continental weathering following the latest Permian mass extinction. Sci. Adv. 2018;4:e1602921. doi: 10.1126/sciadv.1602921. PubMed DOI PMC

White DA, Elrick M, Romaniello S, Zhang F. Global seawater redox trends during the Late Devonian mass extinction detected using U isotopes of marine limestones. Earth Planet. Sci. Lett. 2018;503:68–77. doi: 10.1016/j.epsl.2018.09.020. DOI

Wang G, Zhan R, Percival IG. The end-Ordovician mass extinction: a single-pulse event? Earth-Sci. Rev. 2019;192:15–33. doi: 10.1016/j.earscirev.2019.01.023. DOI

Wang Y, et al. Stratigraphic sequence and sedimentary characteristics of lower Silurian Longmaxi formation in the Sichuan Basin and its peripheral areas. Nat. Gas. Ind. 2015;35:12–21.

Mustafa KA, Sephton MA, Watson JS, Spathopoulos F, Krzywiec P. Organic geochemical characteristics of black shales across the Ordovician-Silurian boundary in the Holy Cross Mountains, central Poland. Mar. Pet. Geol. 2015;66:1042–1055. doi: 10.1016/j.marpetgeo.2015.08.018. DOI

Meyer KM, Kump LR. Oceanic euxinia in Earth history: causes and consequences. Annu. Rev. Earth Planet. Sci. 2008;36:251–288. doi: 10.1146/annurev.earth.36.031207.124256. DOI

Lu W, et al. Late inception of a resiliently oxygenated upper ocean. Science. 2018;361:174–177. PubMed

Krause AJ, et al. Stepwise oxygenation of the Paleozoic atmosphere. Nat. Commun. 2018;9:1–10. doi: 10.1038/s41467-017-02088-w. PubMed DOI PMC

Meyer KM, Ridgwell A, Payne JL. The influence of the biological pump on ocean chemistry: implications for long-term trends in marine redox chemistry, the global carbon cycle, and marine animal ecosystems. Geobiology. 2016;14:207–219. doi: 10.1111/gbi.12176. PubMed DOI PMC

Pohl A, Donnadieu Y, Le Hir G, Buoncristiani J-F, Vennin E. Effect of the Ordovician paleogeography on the (in)stability of the climate. Clim. Discuss. 2014;10:2767–2804. doi: 10.5194/cpd-10-2767-2014. DOI

Middelburg JJ, Soetaert K, Herman PMJ, Heip CHR. Denitrification in marine sediments: a model study. Glob. Biogeochem. Cycles. 1996;10:661–673. doi: 10.1029/96GB02562. DOI

Menard HW, Smith SM. Hypsometry of ocean basin provinces. J. Geophys. Res. 1966;71:4305–4325. doi: 10.1029/JZ071i018p04305. DOI

Soetaert K, Petzoldt T, Setzer RW. Solving differential equations in R: package deSolve. J. Stat. Softw. 2010;33:1–25. PubMed

Soetaert K, Petzoldt T. Inverse modelling, sensitivity and Monte Carlo analysis in R using package FME. J. Stat. Softw. 2010;33:1–28. PubMed

Poulton SW, Canfield DE. Development of a sequential extraction procedure for iron: Implications for iron partitioning in continentally derived particulates. Chem. Geol. 2005;214:209–221. doi: 10.1016/j.chemgeo.2004.09.003. DOI

Canfield DE, Raiswell R, Westrich JT, Reaves CM, Berner RA. The use of chromium reduction in the analysis of reduced inorganic sulfur in sediments and shales. Chem. Geol. 1986;54:149–155. doi: 10.1016/0009-2541(86)90078-1. DOI

Wang X, Planavsky NJ, Reinhard CT, Hein JR, Johnson TM. A Cenozoic seawater redox record derived from 238U/235U in ferromanganese crusts. Am. J. Sci. 2016;316:64–83. doi: 10.2475/01.2016.02. DOI

Planavsky NJ, et al. Evidence for oxygenic photosynthesis half a billion years before the great oxidation event. Nat. Geosci. 2014;7:283–286. doi: 10.1038/ngeo2122. DOI

Cole DB, Zhang S, Planavsky NJ. A new estimate of detrital redox-sensitive metal concentrations and variability in fluxes to marine sediments. Geochim. Cosmochim. Acta. 2017;215:337–353. doi: 10.1016/j.gca.2017.08.004. DOI

Nägler TF, et al. Proposal for an international molybdenum isotope measurement standard and data representation. Geostand. Geoanalytical Res. 2014;38:149–151.

Noordmann J, et al. Uranium and molybdenum isotope systematics in modern euxinic basins: case studies from the central Baltic Sea and the Kyllaren fjord (Norway) Chem. Geol. 2015;396:182–195. doi: 10.1016/j.chemgeo.2014.12.012. DOI

Rudnick, R. L. & Gao, S. Composition of the Continental Crust. in Treatise on Geochemistry: Second Edition 4, 1–51 (Elsevier, 2014).

Voegelin AR, Pettke T, Greber ND, von Niederhäusern B, Nägler TF. Magma differentiation fractionates Mo isotope ratios: Evidence from the Kos Plateau Tuff (Aegean Arc) Lithos. 2014;190–191:440–448. doi: 10.1016/j.lithos.2013.12.016. DOI

Wickson, S. High-Resolution Carbon Isotope Stratigraphy of the Ordovician-Silurian Boundary on Anticosti Island, Quebec: regional and Global Implications. (University of Ottowa, 2011).

Scott C, et al. Tracing the stepwise oxygenation of the Proterozoic ocean. Nature. 2008;452:456–459. doi: 10.1038/nature06811. PubMed DOI

Andersen MB, et al. Closing in on the marine 238U/235U budget. Chem. Geol. 2016;420:11–22. doi: 10.1016/j.chemgeo.2015.10.041. DOI

Brown ST, Basu A, Ding X, Christensen JN, DePaolo DJ. Uranium isotope fractionation by abiotic reductive precipitation. Proc. Natl Acad. Sci. USA. 2018;115:8688–8693. doi: 10.1073/pnas.1805234115. PubMed DOI PMC

Dahl, T. W. et al. Reorganisation of Earth’s biogeochemical cycles briefly oxygenated the oceans 520 Myr ago. Geochemical Perspect. Lett. 210–220, 10.7185/geochemlet.1724 (2017).

Wei GY, et al. Marine redox fluctuation as a potential trigger for the Cambrian explosion. Geology. 2018;46:587–590. doi: 10.1130/G40150.1. DOI

Tissot FLH, Dauphas N. Uranium isotopic compositions of the crust and ocean: Age corrections, U budget and global extent of modern anoxia. Geochim. Cosmochim. Acta. 2015;167:113–143. doi: 10.1016/j.gca.2015.06.034. DOI