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TitleCryogenian interglacial greenhouse driven by enhanced volcanism: evidence from mercury records
AuthorZhu, T; Pan, X; Sun, R; Deng, C; Shen, J; Kwon, S Y; Grasby, S EORCID logo; Xiao, J; Yin, R
SourceEarth and Planetary Science Letters vol. 564, 116902, 2021 p. 1-7,
Alt SeriesNatural Resources Canada, Contribution Series 20210018
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS 100.0000 120.0000 30.0000 20.0000
Subjectsenvironmental geology; tectonics; geochemistry; Science and Technology; Nature and Environment; paleoenvironment; paleoclimatology; glacial history; glaciation; deglaciation; interglacial stages; volcanism; geochemical anomalies; mercury geochemistry; isotopes; organic carbon; carbon dioxide; atmospheric geochemistry; sea water geochemistry; sea sediment geochemistry; bedrock geology; lithology; sedimentary rocks; black shales; biogeochemistry; Neoproterozoic; Cryogenian; Sturtian Glaciation; Marinoan Glaciation; Greenhouse gases; Atmospheric emissions; Climate change; Precambrian; Proterozoic
Illustrationslocation maps; profiles; plots; schematic models
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic, Pearya Terrane, North Ellesmere
Released2021 04 06
AbstractAn ice-free greenhouse interval (ca. 660 ~ 650 Ma) occurred between the global Sturtian (ca. 717 Ma ~ 660 Ma) and Marinoan glaciation (ca. 650 Ma ~ 635 Ma) during the Cryogenian. While volcanic CO2 emissions have been suggested as a trigger for this ice-free interval, evidence for volcanism has been lacking. In this study, spikes in both Hg concentration (76 to 366 ppb) and Hg to total organic carbon ratio (Hg/TOC: 114 to 717 ppb/wt.%) were observed in the Wuhe section of South China, suggesting that extensive volcanic emissions of Hg occurred during the Cryogenian interglacial period. Positive Hg (0.02 to 0.18‰) values were observed in these Hg-rich shales, indicating that the volcanic Hg was cycling in the atmosphere, deposited in seawater, and sequestered to sediment via organic matter burial. Combined with other geochemical proxies (e.g., organic carbon isotope and chemical index of alteration), our results provide the first direct evidence that volcanism played a key role in forming the brief Cryogenian interglacial period.
Summary(Plain Language Summary, not published)
This paper uses a proxy for volcanism in deep time that was developed by researchers at the NRCan to test what caused a brief pause and warm period during a phase in Earth history known as Snow Ball Earth. The earth at this time was extensively (globally) ice covered. However there was a brief reprieve where glaciers retreated and global temperatures rapidly rose. This work demonstrates that this reprieve in ice conditions was related to extensive volcanism releasing CO2 driving global warming. Results show that in deep earth time that global warming occurred in rapid response to CO2 emissions.

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