Perspectives on Proterozoic surface ocean redox from iodine contents in ancient and recent carbonate

Hardisty, Dalton S.; Lu, Zunli; Bekker, Andrey; Diamond, Charles; Gill, Benjamin C.; Jiang, Ganqing; Kah, L. C.; Knoll, Andrew H.; Loyd, S. J.; Osburn, M. R.; Planavsky, Noah J.; Wang, Chun‐Jiang; Zhou, Xiaoli; Lyons, Timothy W.

doi:10.1016/j.epsl.2017.01.032

Cited by 180 publications

(177 citation statements)

References 61 publications

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“…What role other biologically-essential nutrients played in ancient primary productivity is a current avenue of research (e.g., Robbins et al, 2013;Scott et al, 2013;Swanner et al, 2014). Overall, the possible suppression of cyanobacterial productivity by nutrient limitation in the Proterozoic is consistent with the current view of Earth's oxygenation history (e.g., Lyons et al, 2014) and with either limited or transient oxygen presence in the surface ocean (e.g., Hardisty et al, 2014Hardisty et al, , 2017.…”

Section: Iron Formations Primary Productivity and Atmospheric Oxygesupporting

confidence: 67%

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

336

248

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Section: Iron Formations Primary Productivity and Atmospheric Oxygesupporting

confidence: 67%

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

336

248

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“…Such low atmospheric p O 2 levels would likely have produced a surface ocean with low but highly variable O 2 levels that could have stifled eukaryotic diversification and perhaps the origins of animal life—or at least their earliest proliferation (Reinhard et al., ). A weakly oxic surface ocean carries the implication of a shallow and unstable chemocline as well, which has been previously proposed for much of the mid‐Proterozoic (e.g., Gilleaudeau & Kah, ; Hardisty et al., ; Reinhard et al., ). Frequent shoaling of anoxic and, at times, sulfidic waters into productive shelf environments could have been the defining characteristic that held eukaryotes back from rising to ecological significance (Hardisty et al., ; Johnston et al., ).…”

Section: Introductionmentioning

confidence: 62%

“…Generally, low oxygen conditions for the mid‐Proterozoic ocean are supported by numerous past studies (e.g., Canfield, ; Cole et al., ; Cumming et al., ; Gilleaudeau & Kah, ; Hardisty et al., ; Kah et al., ; Liu et al., ; Mitchell & Sheldon, ; Partin et al., ; Planavsky et al., , ; Scott et al., ). However, inherent limitations in the resolution of these studies allow for ample temporal gaps and thus for the possibility that transient oxygenation events may be more important than previously imagined.…”

Section: Discussionmentioning

confidence: 78%

“…In a recent compilation of iodine concentrations in shallow marine carbonates through the Earth's history, the mid‐Proterozoic is characterized by dominantly very low, nonzero I/(Ca+Mg) ratios (Hardisty et al., ). This observation suggests that while surface waters were oxic, the chemocline was likely shallow and unstable and, through mixing, frequently introduced anoxic waters to the surface layer (Hardisty et al., ). One exception to this pattern is the Tieling Formation, which directly underlies the Xiamaling.…”

Section: Discussionmentioning

confidence: 99%

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What the ~1.4 Ga Xiamaling Formation can and cannot tell us about the mid‐Proterozoic ocean

et al. 2018

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Despite a surge of recent work, the evolution of mid-Proterozoic oceanic-atmospheric redox remains heavily debated. Constraining the dynamics of Proterozoic redox evolution is essential to determine the role, if any, that anoxia played in protracting the development of eukaryotic diversity. We present a multiproxy suite of high-resolution geochemical measurements from a drill core capturing the ~1.4 Ga Xiamaling Formation, North China Craton. Specifically, we analyzed major and trace element concentrations, sulfur and molybdenum isotopes, and iron speciation not only to better understand the local redox conditions but also to establish how relevant our data are to understanding the contemporaneous global ocean. Our results suggest that throughout deposition of the Xiamaling Formation, the basin experienced varying degrees of isolation from the global ocean. During deposition of the lower organic-rich shales (130-85 m depth), the basin was extremely restricted, and the reservoirs of sulfate and trace metals were drawn down almost completely. Above a depth of 85 m, shales were deposited in dominantly euxinic waters that more closely resembled a marine system and thus potentially bear signatures of coeval seawater. In the most highly enriched sample from this upper interval, the concentration of molybdenum is 51 ppm with a δ Mo value of +1.7‰. Concentrations of Mo and other redox-sensitive elements in our samples are consistent with a deep ocean that was largely anoxic on a global scale. Our maximum δ Mo value, in contrast, is high compared to published mid-Proterozoic data. This high value raises the possibility that the Earth's surface environments were transiently more oxygenated at ~1.4 Ga compared to preceding or postdating times. More broadly, this study demonstrates the importance of integrating all available data when attempting to reconstruct surface O dynamics based on rocks of any age.

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“…Although low O 2 levels have been suggested for the midProterozoic atmosphere-ocean system (<0.1-1.0% PAL; Canfield, 1998;Reinhard et al, 2013a;Planavsky et al, 2014;Liu et al, 2016;Tang et al, 2016;Hardisty et al, 2017), such conditions imply poorly buffered surface O 2 inventories and the potential for significant spatiotemporal variability Cole et al, 2016;Reinhard et al, 2016;Daines et al, 2017;Hardisty et al, 2017). Indeed, there has been much recent interest in the possibility of dynamic spatiotemporal variations in atmosphere-ocean redox conditions during this time (e.g., Sperling et al, 2014;Gilleaudeau and Kah, 2015;Gilleaudeau et al, 2016;Mukherjee and Large, 2016;Planavsky et al, 2016;Reinhard et al, 2016;Zhang et al, 2016) against a background of lower atmospheric pO 2 compared with today (e.g., Cole et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

Sheen

Kendall

Reinhard

et al. 2018

Geochimica et Cosmochimica Acta

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Emerging geochemical evidence suggests that the atmosphere-ocean system underwent a significant decrease in O 2 content following the Great Oxidation Event (GOE), leading to a mid-Proterozoic ocean (ca. 2.0-0.8 Ga) with oxygenated surface waters and predominantly anoxic deep waters. The extent of mid-Proterozoic seafloor anoxia has been recently estimated using mass-balance models based on molybdenum (Mo), uranium (U), and chromium (Cr) enrichments in organic-rich mudrocks (ORM). Here, we use a temporal compilation of concentrations for the redox-sensitive trace metal rhenium (Re) in ORM to provide an independent constraint on the global extent of mid-Proterozoic ocean anoxia and as a tool for more generally exploring how the marine geochemical cycle of Re has changed through time. The compilation reveals that mid-Proterozoic ORM are dominated by low Re concentrations that overall are only mildly higher than those of Archean ORM and significantly lower than many ORM deposited during the ca. 2.22-2.06 Ga Lomagundi Event and during the Phanerozoic Eon. These temporal trends are consistent with a decrease in the oceanic Re inventory in response to an expansion of anoxia after an interval of increased oxygenation during the Lomagundi Event. Mass-balance modeling of the marine Re geochemical cycle indicates that the mid-Proterozoic ORM with low Re enrichments are consistent with extensive seafloor anoxia. Beyond this agreement, these new data bring added value because Re, like the other metals, responds generally to lowoxygen conditions but has its own distinct sensitivity to the varying environmental controls. Thus, we can broaden our capacity to infer nuanced spatiotemporal patterns in ancient redox landscapes. For example, despite the still small number of data, some mid-Proterozoic ORM units have higher Re enrichments that may reflect a larger oceanic Re inventory during transient episodes of ocean oxygenation. An improved understanding of the modern oceanic Re cycle and a higher temporal resolution for the Re compilation will enable further tests of these hypotheses regarding changes in the surficial Re geochemical cycle in response to variations in atmosphere-ocean oxygenation. Nevertheless, the existing Re compilation and model results are in agreement with previous Cr, Mo, and U evidence for pervasively anoxic and ferruginous conditions in mid-Proterozoic oceans.

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Perspectives on Proterozoic surface ocean redox from iodine contents in ancient and recent carbonate

Cited by 180 publications

References 61 publications

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

What the ~1.4 Ga Xiamaling Formation can and cannot tell us about the mid‐Proterozoic ocean

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

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