Redox fluctuations during the Ediacaran-Cambrian transition, Nanhua Basin, South China: Insights from Cr isotope and REE+Y data

Frank, Anja B.; Klaebe, Robert; Xu, Li

doi:10.1016/j.chemgeo.2019.07.031

Cited by 27 publications

(15 citation statements)

References 82 publications

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“…These elevated δ 53 Cr values of the Yanjiahe and lower Shuijingtuo Formations correspond well with previously reported δ 53 Cr data for sediments deposited during the Ediacaran-early Cambrian transition from the Yangtze Block (Frank et al, 2019;Frei et al, 2020Frei et al, , 2021Wei, Frei, et al, 2020), suggesting that they are representative of the local water conditions at that time. The carbonates of the Zhujiaqing Formation, which is time equivalent to the Yanjiahe Formation, recorded a trend of decreasing δ 53 Cr auth values with increasing authigenic Cr concentrations (Wei, Frei, et al, 2020).…”

Section: Constraining Surface Redox Conditionssupporting

confidence: 90%

“…While the detrital component of marine sediments is expected to mirror the Cr isotope composition of its source materials, the authigenic mineral component is assumed to record the geochemistry of the ambient waters it precipitated from. Hence, one of the greatest challenges in applying Cr isotopes as a redox proxy is estimating the authigenic Cr isotope composition (Frank et al., 2019, 2020; Gilleaudeau et al., 2016; Reinhard et al., 2014). Until recently, the Cr isotope composition of bulk detrital sediment was generally assumed to fall within a narrow range typical for igneous rocks (δ 53 Cr det = −0.124 ± 0.101‰; Schoenberg et al., 2008), but recent studies have reported a wider range in δ 53 Cr det of up to 0.2‰ (Frank et al., 2019; Huang et al., 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Hence, one of the greatest challenges in applying Cr isotopes as a redox proxy is estimating the authigenic Cr isotope composition (Frank et al, 2019(Frank et al, , 2020Gilleaudeau et al, 2016;Reinhard et al, 2014). Until recently, the Cr isotope composition of bulk detrital sediment was generally assumed to fall within a narrow range typical for igneous rocks (δ 53 Cr det = −0.124 ± 0.101‰; Schoenberg et al, 2008), but recent studies have reported a wider range in δ 53 Cr det of up to 0.2‰ (Frank et al, 2019;Huang et al, 2018). The few Yanjiahe and Shuijingtuo samples characterized by EF Cr < 1 recorded bulk δ 53 Cr 0-0.14‰.…”

Section: Constraining the Authigenic δ 53 Cr Compositionmentioning

confidence: 99%

“…The Yangtze Block in South China is characterized by a well exposed marine sedimentary succession rendering it an ideal setting to study Earth surface redox fluctuations. Hence, it has been the target of many geochemical studies aiming to reconstruct seawater redox conditions during the Ediacaran‐Cambrian transition using various proxies such as rare earth elements (REE) (e.g., Ling et al., 2013; Zhai, Wu, Ye, Zhang, & An, 2018) or redox sensitive elements (e.g., Dong et al., 2019; Frank et al., 2019; Wei, Frei, et al., 2020; Wei, Planavsky, et al., 2020). Recent studies constraining the seawater redox condition of the Yangtze Block during this time period have increasingly relied on Cr isotopes in ancient marine sediments as a paleoredox proxy (e.g., Frank et al., 2019; Wei, Frei, et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Constraining Shallow Seawater Oxygenation for the Yangtze Platform During the Early Cambrian

Frank

Klaebe

2021

Paleoceanog and Paleoclimatol

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Section: Constraining Surface Redox Conditionssupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Constraining the Authigenic δ 53 Cr Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraining Shallow Seawater Oxygenation for the Yangtze Platform During the Early Cambrian

Frank

Klaebe

2021

Paleoceanog and Paleoclimatol

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“…For example, the modern seawater is characterized by a negative Ce anomaly in the REE abundance pattern because Ce(IV) is less soluble and has a shorter residence time than Ce(III) in natural water . The Ce anomaly (Ce/Ce*) in ancient marine sediments has been successfully used as a paleo-redox proxy. − Zhang et al proposed that the high Ce 4+ /Ce 3+ values in zircons reflected high oxygen fugacity in the magma, indicating that the amplitude of the Ce anomaly can be an oxybarometer. In the meanwhile, the chemical speciation and solubility of Ce in water were closely related to pH and Eh conditions. − Furthermore, Ce is a lithophile and highly incompatible element in magmatic systems, which preferentially remains in the melt.…”

Section: Introductionmentioning

confidence: 99%

Single-Stage Extraction Technique for Ce Stable Isotopes and Measurement by MC-ICP-MS

Liu

Zhang

et al. 2021

Anal. Chem.

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The separation of Ce from other rare earth elements has not been well established because of their similar geochemical properties. In this study, we report a single-stage extraction technique to purify Ce from natural samples with Eichrom DGA resin. This method separates Ce effectively from matrices and interfering elements, such as Ba, La, and Nd. The Ce elution curve would not drift with different Ce loading masses and rock types. The Ce isotope compositions were measured using a Thermo Scientific Neptune Plus multicollector (MC)-inductively coupled plasma (ICP)-mass spectrometry (MS) instrument. The instrumental mass bias of Ce isotopes was corrected with a sample-standard bracketing combined with a Sm-doping method. The δ142Ce values of standard solutions (CDUT-Ce and JMC304) relative to National Institute of Standards and Technology SRM 3110 measured were +0.128 ± 0.028‰ (2SD, N = 30) and 0.005 ± 0.038‰ (2SD, N = 30), respectively. The reproducibility for δ142Ce was better than 0.040‰. The Ce isotopic compositions of nine United States Geological Survey standard rocks, including carbonatite, basalt, andesite, quartz latite, dolerite, rhyolite, and granodiorite, were measured in this study. Our result showed that δ142Ce values of these rocks varied slightly, indicating that insignificant fractionation occurred during igneous processes. The technique proposed in this study is simple and time-efficient, which is beneficial for further studies on Ce isotope geochemistry.

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The record of sea water chemistry evolution during the Ediacaran–Cambrian from early marine cements

Xiong

Wood

Pichevin

2022

The Depositional Record

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The Ediacaran-Cambrian Radiation marks the widespread appearance of metazoans and calcareous biomineralised hard parts. These innovations occurred during an interval of dynamic changes in marine redox and sea water chemistry. Here, changing carbonate mineralogy, Mg/Ca ratios and rare earth element concentrations including the relative abundance of cerium (Ce anomaly: Ce anom ) are documented to track sea water oxygen levels, in well-preserved early marine cements from shallow marine reefs from Cambrian Stages 2-4 (ca 525-512 Ma). First, integrating the mineralogical data with published records, several shifts in dominant carbonate mineralogy are inferred: 'dolomite-aragonite seas' in the late Ediacaran; 'aragonite/high-Mg calcite seas' in Cambrian Stage 2; a temporary shift to a 'calcite sea' during early Cambrian Stage 3; an 'aragonite sea' between late Cambrian Stage 3 and late Cambrian Stage 4, then a gradual shift from mixed 'aragonite-calcite seas' during the middle and upper Cambrian towards a 'calcite sea' by the early Ordovician. Second, based on measured mMg/ Ca in early marine cements, calculated sea water mMg/Ca at 15 and 35°C ranges from 1.2 to 0.8 in Cambrian Stage 2, 0.7-0.4 in Stage 3 and 1.4-0.9 in Stage 4 respectively. Finally, analysed Ce anom data combined with existing Ce anom data suggest potentially three phases of global oxic expansion. First, a long-lived phase of progressive oxygenation during the late Ediacaran to Fortunian (ca 550-540 Ma; average Ce anom from 0.99 to 0.41), and possibly two shorter phases during early Cambrian Stage 3 (ca 519 Ma; average Ce anom from 0.91 to 0.40) and Stage 4 (ca 512 Ma; average Ce anom from 1.02 to 0.49), bounded by intervals of more dominant anoxia. Summarising, these data demonstrate that early marine cements offer an underused and high-resolution archive of shallow marine redox and sea water chemistry through this critical transition in Earth's evolution.

show abstract

Redox fluctuations during the Ediacaran-Cambrian transition, Nanhua Basin, South China: Insights from Cr isotope and REE+Y data

Cited by 27 publications

References 82 publications

Constraining Shallow Seawater Oxygenation for the Yangtze Platform During the Early Cambrian

Constraining Shallow Seawater Oxygenation for the Yangtze Platform During the Early Cambrian

Single-Stage Extraction Technique for Ce Stable Isotopes and Measurement by MC-ICP-MS

The record of sea water chemistry evolution during the Ediacaran–Cambrian from early marine cements

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