Characteristics of the carbon cycle in late Mesoproterozoic: Evidence from carbon isotope composition of paired carbonate and organic matter of the Shennongjia Group in South China

Li, Dongdong; Luo, Genming; Yang, Hao; She, Zhenbing; Papineau, Dominic; Li, Chao

doi:10.1016/j.precamres.2022.106726

Cited by 7 publications

(8 citation statements)

References 146 publications

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“…Furthermore, the δ 13 C org data exhibit no correlation with total organic carbon contents (Supplementary Figure 1), whereas alteration would have predicted an inverse correlation. 15 Thus, diagenetic alteration can be largely ruled out and both the carbonate and organic carbon isotope results are deemed to be reliable.…”

Section: Resultsmentioning

confidence: 99%

“…-it is quite possible different mechanisms played more important roles at different times. Following the decoupled Majiatun anomaly, there were not one, 2 but two isotopic anomalies that were both coupled, the Bitter Springs 2 and the Islay (a.k.a Garvellach) 15 anomalies. The duration for shrinking the initial DOC pool following the boring billion in between the decoupled Majiatun anomaly and the coupled Bitter Springs anomaly was ~130 million years.…”

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confidence: 99%

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Carbonate�Corganic decoupling during the first Neoproterozoic carbon isotope excursion

Mitchell,

Feng,

Zhang

et al. 2023

TIG

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The Neoproterozoic Era (1000�C539 Ma) experienced repeated negative carbon isotope excursions, representing the largest negative excursions in Earth history and their origins remain enigmatic. One salient observation is that unlike younger Phanerozoic carbon isotope excursions that almost exclusively exhibit covariation in the carbon isotopes of carbonate and organic carbon, about half of Neoproterozoic excursions are expressed in carbonate carbon isotopes (��13Ccarb) but their organic carbon isotopes (��13Corg) lack the same anomaly. Documenting which excursions exhibit carbonate�Corganic coupling or decoupling may provide a possible clue as to the enigmatic dynamics of the anomalous Neoproterozoic carbon cycle. We report here that a newly recognized and the first Neoproterozoic carbon isotope anomaly also exhibits decoupling. Thus, the ca. 940 Ma Majiatun anomaly now represents the oldest-known decoupled Neoproterozoic excursion��300 m.y. earlier than previously thought. Ruling out altogether or mostly merely localized artifacts such as diagenesis, changes in water depth, and contamination of detrital organic matter, we interpret this new evidence of carbonate�Corganic ��13C decoupling in the context of other anomalies through time. Although the remineralization of a large pool of dissolved organic carbon (DOC) was proposed to explain late Neoproterozoic ��13C decoupled anomalies, our earlier evidence of decoupling suggests this pool was much more ancient. Our new data also require the temporal oscillation between decoupling and coupling of the Neoproterozoic carbon cycle, implying a dynamic diminution of the large Precambrian DOC pool reflective of the rising but equally variable oxygenation of the oceans and rise of animal life at this time.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Carbonate�Corganic decoupling during the first Neoproterozoic carbon isotope excursion

Mitchell,

Feng,

Zhang

et al. 2023

TIG

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“…Approximately 5 to 50 g of homogeneous rock powder were decarbonated with 10% HCl at room temperature for 24 hours under episodic agitation ( 68 ). The pH of the supernatant was measured before washing with HCl.…”

Section: Methodsmentioning

confidence: 99%

Distinctive volcanic ash–rich lacustrine shale deposition related to chemical weathering intensity during the Late Triassic: Evidence from lithium contents and isotopes

Liu,

Li,

Jiang

et al. 2024

Sci. Adv.

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The Late Triassic Carnian Pluvial Episode (CPE) witnessed enormous climate change closely associated with volcanic activity. However, the coupling relationship between volcanic activity and climate change, which may be linked to chemical weathering, has not yet been fully uncovered. We used lithium contents and isotopes of volcanic ash (VA)–bearing lacustrine shale to constrain their deposition pathways and response to climate changes, i.e., weathering intensity, during the Late Triassic era. Elevated δ 7 Li (i.e., >2.5‰) and low Li contents (i.e., <65 microgram per gram) in shale likely document the direct depositing of volcanic lithium from airborne VA, which mainly inherited Earth’s interior δ 7 Li signal. By contrast, shale yields markedly high lithium contents (i.e., >135 microgram per gram), alongside relatively low δ 7 Li (i.e., <0‰), likely implying waterborne VA dominated by intensified weathering under a super humidity climate. Hence, this study provides evidence for the differential VA-rich shale deposition model related to chemical weathering states synchronous with climate changes during the CPE period.

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“…It means the reconstruction may be valid in first order despite the Luanshigou pole may have a 35-myr age uncertainty. Li et al, 2022;Tian et al, 2018;Zou et al, 2019) and coeval strata from Laurentia and Siberia (Bartley et al, 2007;Frank et al, 2003;Whelan et al, 1990). Abbreviations: NYB = northern Yangtze subblock; DWK = Dawokeng Formation; KSS = Kuangshishan Formation; Fm = Formation; Gp = Group; Sp = Supergroup.…”

Section: Connection Between the Nyb And Sw Laurentia In Late Mesoprot...mentioning

confidence: 99%

“…Figure 11. δ 13 C carb correlations of the Lower Shennongjia Group (D Li et al, 2022;Tian et al, 2018;Zou et al, 2019). and coeval strata from Laurentia and Siberia(Bartley et al, 2007;Frank et al, 2003;Whelan et al, 1990).…”

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confidence: 99%

New Paleomagnetic Results From the Late Mesoproterozoic Luanshigou Formation, Shennongjia Group in South China and Their Implications for the Pre‐Grenvillian Connections Between South China Blocks and Southwestern Laurentia

Liu,

Zhang,

et al. 2024

JGR Solid Earth

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The identification of the Grenvillian‐age ophiolite suites in the Yangtze block in recent years suggested that the northern Yangtze subblock (NYB) and the southern Yangtze subblock (SYB) were once separated by an ocean in late Mesoproterozoic. Although some paleogeographic models advocated the Pre‐Grenvillian connections between the south China blocks and Laurentia, none of them has been paleomagnetically tested. Here we report the new paleomagnetic results obtained from the ∼1,270 Ma purplish‐red muddy dolomite beds of the Luanshigou Formation, Shennongjia Group, NYB, providing new constraints for reconstructing the paleogeographic positions of the south China blocks in late Mesoproterozoic. A total of 447 samples underwent stepwise thermal demagnetization. Two components were identified. The low‐temperature component is interpreted as the recent viscous remnant magnetization. The high‐temperature component was obtained from 64 samples below 580°C and from 177 samples below 690°C, directed northeast‐up or southwest‐down, antipodally, positioning the paleomagnetic pole at 18.5°S, 74.4°E (dm/dp = 2.5/1.6°). Rock magnetic results demonstrate that the magnetic carriers in purplish‐red dolomite and pale‐pink dolomite are predominated by hematite and magnetite, respectively. The data quality is supported by an inverse baked contact test, a B‐class reversal test, and the paleomagnetic pole is distinct from any younger poles of the region. Based on the paleomagnetic results, aided by geological evidence, we propose a reconstruction in which the NYB was juxtaposed to southwestern Laurentia in the late Mesoproterozoic and suggest that the late Mesoproterozoic Miaowan‐Shimian ophiolite zone in the Yangtze block was likely an extension of the Grenville belt of Laurentia.

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Characteristics of the carbon cycle in late Mesoproterozoic: Evidence from carbon isotope composition of paired carbonate and organic matter of the Shennongjia Group in South China

Cited by 7 publications

References 146 publications

Carbonate�Corganic decoupling during the first Neoproterozoic carbon isotope excursion

Carbonate�Corganic decoupling during the first Neoproterozoic carbon isotope excursion

Distinctive volcanic ash–rich lacustrine shale deposition related to chemical weathering intensity during the Late Triassic: Evidence from lithium contents and isotopes

New Paleomagnetic Results From the Late Mesoproterozoic Luanshigou Formation, Shennongjia Group in South China and Their Implications for the Pre‐Grenvillian Connections Between South China Blocks and Southwestern Laurentia

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