Congruent Permian-Triassic δ238U records at Panthalassic and Tethyan sites: Confirmation of global-oceanic anoxia and validation of the U-isotope paleoredox proxy

Zhang, Feifei; Algeo, Thomas J.; Romaniello, Stephen J.; Cui, Ying; Zhao, Laishi; Chen, Zhong‐Qiang; Anbar, Ariel D.

doi:10.1130/g39695.1

Cited by 116 publications

(93 citation statements)

References 28 publications

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“…The spike‐sample mixtures were evaporated to dryness and taken up in 3N HNO 3 . Uranium was purified using the UTEVA method for isotopic analysis (Brennecka et al, ; Chen et al, ; Kendall et al, ; Romaniello et al, ; Weyer et al, ; Zhang, Algeo, Cui, et al, ; Zhang, Algeo, Romaniello, et al, ; Zhang, Romaniello, et al, ; Zhang, Xiao, et al, ). All samples were put through UTEVA resin twice in order to completely remove matrix ions.…”

Section: Methodsmentioning

confidence: 99%

“…However, subsequent work by Chen et al () and Tissot et al (), who revisited the dolomitization question with a larger sample set from several cores through the Bahamian carbonate platform, shows no statistically significant differences between calcite and dolomite. There are now δ 238 U data from seven widely spaced carbonate sections spanning the Permian–Triassic boundary [the Dajiang (Lau et al, ), Guandao (Lau et al, ), Dawen (Brennecka et al, ), and Daxiakou (Elrick et al, ) sections in South China; the Taşkent section in Turkey (Lau et al, ); the Zal section in Iran (Zhang, Romaniello, et al, ); and the Kamura section in Japan (Zhang, Algeo, Romaniello, et al, )]. All of these sections show strikingly similar trends in δ 238 U across the Permian–Triassic boundary, which is remarkable because they span 1,000s of km—even in different ocean basins—and have experienced very different diagenetic histories, including dolomitization.…”

Section: Evidence For Primary Oceanographic Signalsmentioning

confidence: 99%

“…Marine carbonate sediments have been demonstrated to record the δ 238 U of seawater, subject to a 0.2‰–0.4‰ offset, which likely reflects incorporation of U(IV) into shallow sediments from anoxic porewaters (Chen et al, ; Romaniello, Herrmann, & Anbar, ; Tissot et al, ). Studies comparing the trends and absolute values of δ 238 U in coeval Permian–Triassic carbonate sediments from around the world have shown excellent agreement, demonstrating that carbonates may provide a robust record of variations in seawater δ 238 U (Brennecka et al, ; Elrick et al, ; Lau et al, ; Zhang, Algeo, Romaniello, et al, ; Zhang, Romaniello, et al, ).…”

Section: Introductionmentioning

confidence: 97%

“…The U isotope system ( 238 U/ 235 U, denoted as δ 238 U) measured in carbonate sedimentary rocks is a more direct probe of global ocean redox conditions and can be used to place quantitative constraints on the extent of global redox changes (Brennecka, Herrmann, Algeo, & Anbar, ; Clarkson et al, ; Elrick et al, ; Lau et al, ; Tostevin et al, ; Wei et al, ; Zhang, Algeo, Cui, et al, ; Zhang, Algeo, Romaniello, et al, ; Zhang, Romaniello, et al, ; Zhang, Xiao, et al, ). The power of U isotopes as a global proxy derives from the fact that in the modern ocean U has a long residence time, ~500 kyr (Dunk, Mills, & Jenkins, ), and hence, δ 238 U is uniform in the open ocean (e.g., Tissot & Dauphas, ).…”

Section: Introductionmentioning

confidence: 99%

“…The power of U isotopes as a global proxy derives from the fact that in the modern ocean U has a long residence time, ~500 kyr (Dunk, Mills, & Jenkins, ), and hence, δ 238 U is uniform in the open ocean (e.g., Tissot & Dauphas, ). Although the concentration and residence time of U in seawater would both be reduced during times of expanded marine anoxia, studies suggest that the U isotope composition of open ocean seawater was likely uniform even during periods of expanded anoxia (Clarkson et al, ; Zhang, Algeo, Romaniello, et al, ; Zhang, Xiao, et al, ). Seawater δ 238 U varies with redox conditions because the reduction of dissolved U(VI) to U(IV), which is immobilized in anoxic sediments, results in a large and detectable change in δ 238 U (0.6‰–0.85‰), favoring the 238 U over 235 U in the reduced species (Andersen et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Global marine redox changes drove the rise and fall of the Ediacara biota

et al. 2019

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The role of O2 in the evolution of early animals, as represented by some members of the Ediacara biota, has been heavily debated because current geochemical evidence paints a conflicting picture regarding global marine O2 levels during key intervals of the rise and fall of the Ediacara biota. Fossil evidence indicates that the diversification the Ediacara biota occurred during or shortly after the Ediacaran Shuram negative C‐isotope Excursion (SE), which is often interpreted to reflect ocean oxygenation. However, there is conflicting evidence regarding ocean oxygen levels during the SE and the middle Ediacaran Period. To help resolve this debate, we examined U isotope variations (δ238U) in three carbonate sections from South China, Siberia, and USA that record the SE. The δ238U data from all three sections are in excellent agreement and reveal the largest positive shift in δ238U ever reported in the geologic record (from ~ −0.74‰ to ~ −0.26‰). Quantitative modeling of these data suggests that the global ocean switched from a largely anoxic state (26%–100% of the seafloor overlain by anoxic waters) to near‐modern levels of ocean oxygenation during the SE. This episode of ocean oxygenation is broadly coincident with the rise of the Ediacara biota. Following this initial radiation, the Ediacara biota persisted until the terminal Ediacaran period, when recently published U isotope data indicate a return to more widespread ocean anoxia. Taken together, it appears that global marine redox changes drove the rise and fall of the Ediacara biota.

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Section: Methodsmentioning

confidence: 99%

Section: Evidence For Primary Oceanographic Signalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Global marine redox changes drove the rise and fall of the Ediacara biota

et al. 2019

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Assessing the Effect of Large Igneous Provinces on Global Oceanic Redox Conditions Using Non‐traditional Metal Isotopes (Molybdenum, Uranium, Thallium)

Kendall

Andersen

Owens

2021

Large Igneous Provinces

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During the past two decades, the isotope ratios of numerous redox-sensitive metals in sedimentary archives (particularly organic-rich mudrocks, carbonates, and iron formations) have emerged as valuable tools for constraining changes in global oceanic redox conditions. The long modern ocean residence times of Mo (~440 kyr; Miller et al., 2011), U (~450 kyr; Dunk et al., 2002), and Tl (~20 kyr;Nielsen et al., 2017) relative to ocean mixing times (~1-2 kyr; Sarmiento & Gruber, 2006), together with the distinctive isotope fractionations observed for metal removal into diverse marine sinks, means that the isotopic composition of these metals can serve as global oceanic redox tracers. Redox-sensitive metal isotopes have become an attractive tool with which to place constraints on the magnitude of oceanic anoxia associated with the emplacement of LIPs. The overarching approach is to use sedimentary rocks (organic-rich mudrocks for Mo, U, and Tl; carbonates for U) to infer the isotopic composition of coeval global seawater before, during, and after LIP emplacement, and employ isotopic mass

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Marine Anoxia and Ocean Acidification During the End‐Permian Extinction

Cui

Zhang

Wang

et al. 2021

Large Igneous Provinces

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The largest mass extinction event in the Phanerozoic, known as the end-Permian mass extinction (or EPME, ca. 252 Ma) is coincident with the main eruption phase of Siberian Traps volcanism (ca. 252 to 250 Ma), a large igneous province (LIP). This LIP is estimated to have a volume larger than 2 × 10 6 km 3 and to have released both mantle carbon dioxide (CO 2 ) through extrusions and thermogenic methane (CH 4 ) and carbon dioxide (CO 2 ) through intru sions. The climatic consequences of these greenhouse gases is detrimental to both marine and terrestrial life and may have delayed the recovery of ecosystems after the extinction. Quantitatively, the amount of CO 2 released can be estimated using global carbon (C) cycle model or plant and soil-based proxies with varying time resolution. In light of the recent advances in geochemical proxies of ocean anoxia and acidification, we review the latest uranium isotopes (δ 238 U) and calcium isotope (δ 44/40 Ca) records and Earth system modeling results to summarize the environ mental response to the forcing of increased atmospheric CO 2 concentrations. The extent of increase in oceanic anoxic area can be estimated by δ 238 U, and the δ 44/40 Ca records may be used to evaluate ocean acidification. This evidence suggests that excessive nutrient load in the ocean (decreased strength of meridional overturning circula tion) and ocean acidification in poorly buffered seawater (potentially triggered by the Siberian Traps LIP) worked together to create the most severe biological crisis and delayed recovery of life in the Earth's history.

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Congruent Permian-Triassic δ238U records at Panthalassic and Tethyan sites: Confirmation of global-oceanic anoxia and validation of the U-isotope paleoredox proxy

Cited by 116 publications

References 28 publications

Global marine redox changes drove the rise and fall of the Ediacara biota

Global marine redox changes drove the rise and fall of the Ediacara biota

Assessing the Effect of Large Igneous Provinces on Global Oceanic Redox Conditions Using Non‐traditional Metal Isotopes (Molybdenum, Uranium, Thallium)

Marine Anoxia and Ocean Acidification During the End‐Permian Extinction

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