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TitleAnomalous fractionation of mercury isotopes in the Late Archean atmosphere
AuthorZerkle, A L; Yin, R; Chen, C; Li, X; Izon, G J; Grasby, S EORCID logo
SourceNature Communications vol. 11, issue 1, 1709, 2020 p. 1-9, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200064
PublisherNature Research
Mediapaper; on-line; digital
File formatpdf; html
Subjectsenvironmental geology; Nature and Environment; Science and Technology; mercury; isotopes; Archean; atmospheric geochemistry; sediments; sedimentary rocks; Precambrian
Illustrationsplots; figures
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic, Pearya Terrane, North Ellesmere
Released2020 04 06
AbstractEarth's surface underwent a dramatic transition ~2.3 billion years ago when atmospheric oxygen first accumulated during the Great Oxidation Event, but the detailed composition of the reducing early atmosphere is not well known. Here we develop mercury (Hg) stable isotopes as a proxy for paleoatmospheric chemistry and use Hg isotope data from 2.5 billion-year-old sedimentary rocks to examine changes in the Late Archean atmosphere immediately prior to the Great Oxidation Event. These sediments preserve evidence of strong photochemical transformations of mercury in the absence of molecular oxygen. In addition, these geochemical records combined with previously published multi-proxy data support a vital role for methane in Earth's early atmosphere.
Summary(Plain Language Summary, not published)
This paper uses novel tools developed at NRCan to examine the most significant event in Earth history, the transition from and anoxic to the modern oxic world we live in. While earlier work has tracked this change through the marine environment, how this occurred in the atmosphere is less certain. Results in this study show that the oxygenation of the planet was a complex stepped process.

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