Estimates of atmospheric O2 in the Paleoproterozoic from paleosols

Kanzaki, Yoshiki; Murakami, Takashi

doi:10.1016/j.gca.2015.11.022

Cited by 23 publications

(15 citation statements)

References 115 publications

(228 reference statements)

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“…By embedding our estimates of O 2 production in a global redox balance framework (see Supporting information Methods), we can estimate the reductant fluxes from Earth's interior required to balance the global O 2 cycle across the range of parameters explored here (Table 2). We use a previously published parameterization for O 2 consumption associated with the oxidative weathering of organic matter (Daines, Mills, & Lenton, 2017;Lasaga & Ohmoto, 2002) (Supporting information equation S44) and ferrous iron (Kanzaki & Murakami, 2016;Yokota, Kanzaki, & Murakami, 2013) year −1 . Given that even the modern solid Earth reductant flux cannot be constrained with a precision better than ~1 Tmol O 2 equivalents year −1 , it is clear that our "Low O 2 " retrieval is fully consistent with a closed, stable redox balance.…”

Section: A Global Redox Budget For the Mid-proterozoicmentioning

confidence: 99%

“…Kanzaki & Murakami, 2016; Yokota,Kanzaki, & Murakami, 2013) (Supporting information equation S45) (see Supporting information Methods), combined with the O 2 production fluxes derived above, to estimate that an external reductant flux of 2.75 Tmol O 2 equivalents year −1 is required to satisfy global redox balance under the mid-Proterozoic Earth system state retrieved by our model for our "Low O 2 " scenario (Figure 5a). This can be compared to a modern reductant flux to Earth's surface from volcanism, hydrothermal systems and geologic/thermogenic CH 4 production of 1.5−2.1 Tmol O 2 equivalents…”

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confidence: 99%

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A sluggish mid‐Proterozoic biosphere and its effect on Earth's redox balance

2018

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The possibility of low but nontrivial atmospheric oxygen (O 2 ) levels during the mid‐Proterozoic (between 1.8 and 0.8 billion years ago, Ga) has important ramifications for understanding Earth's O 2 cycle, the evolution of complex life and evolving climate stability. However, the regulatory mechanisms and redox fluxes required to stabilize these O 2 levels in the face of continued biological oxygen production remain uncertain. Here, we develop a biogeochemical model of the C‐N‐P‐O 2 ‐S cycles and use it to constrain global redox balance in the mid‐Proterozoic ocean–atmosphere system. By employing a Monte Carlo approach bounded by observations from the geologic record, we infer that the rate of net biospheric O 2 production was Tmol year −1 (1σ), or ~25% of today's value, owing largely to phosphorus scarcity in the ocean interior. Pyrite burial in marine sediments would have represented a comparable or more significant O 2 source than organic carbon burial, implying a potentially important role for Earth's sulphur cycle in balancing the oxygen cycle and regulating atmospheric O 2 levels. Our statistical approach provides a uniquely comprehensive view of Earth system biogeochemistry and global O 2 cycling during mid‐Proterozoic time and implicates severe P biolimitation as the backdrop for Precambrian geochemical and biological evolution.

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Section: A Global Redox Budget For the Mid-proterozoicmentioning

confidence: 99%

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confidence: 99%

A sluggish mid‐Proterozoic biosphere and its effect on Earth's redox balance

2018

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“…In the case of Archaean paleosols formed prior to the GOE, more carefully addressing whether the high magnitude of Fe(II) loss or mobility observed is pedogenic or the result of post-depositional disturbance (Rye & Holland, 1998) (Kanzaki & Murakami, 2015;Kasting, 1987;Sheldon, 2006;Sleep & Zahnle, 2001…”

Section: Comparison With Other Weathering Profiles: a Role For Cr(imentioning

confidence: 99%

Chromium geochemistry of the ca. 1.85 Ga Flin Flon paleosol

2016

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Fractionation of stable Cr isotopes has been measured in Archaean paleosols and marine sedimentary rocks and interpreted to record the terrestrial oxidation of Cr(III) to Cr(VI), providing possible indirect evidence for the emergence of oxygenic photosynthesis. However, these fractionations occur amidst evidence from other geochemical proxies for a pervasively anoxic atmosphere. This study examined the Cr geochemistry of the ca. 1.85 Ga Flin Flon paleosol, which developed under an atmosphere unambiguously oxidising enough to quantitatively convert Fe(II) to Fe(III) during pedogenesis. The paleosol shows an extreme range in Cr isotope composition of 2.76 ‰ δ Cr. The protolith greenstone (δ Cr: -0.23 ‰), the deepest weathering horizon (δ Cr: -0.15 to -0.23 ‰) and a residual corestone in the upper paleosol (δ Cr: -0.01 ‰) all exhibit Cr isotopic compositions comparable to unaltered igneous rocks. The most significant isotopic fractionation is preserved in the areas influenced by oxidative subaerial weathering (i.e. increase in Fe(III)/Fe(II)) and the greatest loss of mobile elements. The uppermost paleosol horizon is both Cr and Mn depleted and offset to significantly Cr-enriched compositions (δ Cr values between +1.50 and +2.38 ‰), which is not easily modelled with the oxidation of Cr(III) and loss of isotopically heavy Cr(VI). Instead, the currently preferred model for these data invokes the open-system removal of isotopically light aqueous Cr(III) during either pedogenesis or subsequent hydrothermal/metamorphic alteration. The Cr enrichment would then represent the preferential dissolution or complexation of isotopically light aqueous Cr(III) species (enhanced by lower pH conditions and possibly the presence of complexing ligands) and/or the residual signature from preferential adsorption of isotopically heavy Cr(III). Both scenarios would contradict the widely held assumption that only redox reactions of Cr can generate large magnitude isotopic fractionations and, if substantiated, non-redox isotope effects would complicate the conclusive fingerprinting of ancient atmospheric O from Cr isotope data alone.

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“…Paleosols are formed as continental sediments at the Earth's surface and yield valuable information about the ambient environment, climate, and ecosystems at the time of formation (Retallack, ; Sayyed, ; Sheldon & Tabor, ; Tabor & Myers, ) and thus are long‐term recorders of the critical zone (Ashley, Beverly, Sikes, & Driese, ; Brantley, Goldhaber, & Ragnarsdottir, ; Nordt & Driese, ). A wide range of paleosol‐based approaches used for reconstruction of terrestrial paleoclimatic conditions and paleoatmospheric chemistry in paleosols include the stable isotopic composition of paleosol carbonates (Gao et al, ; Huang, Retallack, & Wang, ; Huang, Retallack, Wang, & Huang, ; Hyland & Sheldon, ), pedogenic magnetic minerals (e.g., goethite/hematite) ratios in the B horizons of paleosols (Hyland, Sheldon, Voo, Badgley, & Abrajevitch, ), depth to Bk horizons beneath paleosols surfaces (Pan & Huang, ; Retallack, ), depth to horizons enriched in pedogenic gypsum (Retallack & Huang, ), and bulk geochemical analysis/Fe contents of paleosols or iron–manganese nodules in paleo‐Vertisols (Gallagher & Sheldon, ; Huang & Gong, ; Kanzaki & Murakami, ; Nordt & Driese, ; Opluštil, Lojka, Rosenau, Strnad, & Sýkorová, ). Clumped isotope thermometry of pedogenic carbonates, which indicates the temperature formation of paleosol carbonate, is increasingly employed in paleotemperature estimate (Eiler, ; Ghosh et al, ; Quade, Eiler, Daeron, & Achyuthan, ).…”

Section: Introductionmentioning

confidence: 99%

Lower and upper Cretaceous paleosols in the western Sichuan Basin, China: Implications for regional paleoclimate

Wen

Huang

2018

Geological Journal

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Pedogenic features of paleosols preserved in the lower and upper Cretaceous sedimentary strata of the western Sichuan Basin, China, were described and examined in terms of their macromorphology and micromorphology, mineralogy, and geochemistry. These Cretaceous paleosols (entisols, inceptisols, and aridisols) are analogous to modern soil orders based on soil taxonomy (Soil Survey Staff, 2014). A quantitative reconstruction of paleoclimates inferred from the geochemical composition of paleosol horizons, depth to carbonate nodules, and the stable oxygen isotopic composition of pedogenic carbonates in paleosols indicates that a cool-arid climate associated with short-term subhumid fluctuations prevailed in the early Cretaceous (Hauterivian) and a cool-arid climate regime existed in the late Cretaceous (Maastrichtian) of the Sichuan Basin. Atmospheric CO 2 concentrations estimated from the paleosol barometer indicated values between 156 ± 138 and 753 ± 339 ppmv for the Hauterivian and between 110 ± 71 and 235 ± 77 ppmv for the middle-lateMaastrichtian. An overall coupling between atmospheric pCO 2 and paleotemperature occurred in the Sichuan Basin, while the covariations are likely linked to global cooling events in the Maastrichtian and/or are likely associated with the Faraoni oceanic anoxic event (F-OAE) during the late Hauterivian. Paleoclimate variations in the Sichuan Basin were controlled by regional paleogeography, the prevalence of subtropical high-pressure systems, monsoonal circulation, and the atmospheric CO 2 level in the early and late Cretaceous.

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Estimates of atmospheric O2 in the Paleoproterozoic from paleosols

Cited by 23 publications

References 115 publications

A sluggish mid‐Proterozoic biosphere and its effect on Earth's redox balance

A sluggish mid‐Proterozoic biosphere and its effect on Earth's redox balance

Chromium geochemistry of the ca. 1.85 Ga Flin Flon paleosol

Lower and upper Cretaceous paleosols in the western Sichuan Basin, China: Implications for regional paleoclimate

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