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TitleClimate/ocean dynamics and possible atmospheric mercury depletion events during the Late Sturtian deglaciation
AuthorSun, R; Grasby, S EORCID logo; Shen, J; Xiao, J; Yin, R
SourceChemical Geology vol. 598, 120830, 2022 p. 1-6,
Alt SeriesNatural Resources Canada, Contribution Series 20220032
Mediapaper; digital; on-line
File formatpdf; html
SubjectsScience and Technology; Nature and Environment; Precambrian
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic, Pearya Terrane, North Ellesmere
Released2022 03 26
AbstractLate Sturtian deglaciation, resulting in development of oxic conditions and deposition of banded iron formations (BIFs), was a pivotal period in evolution of global ocean chemistry. The driving forces behind these Neoproterozoic BIFs and climatic/oceanic changes remain controversial, however. Here we use mercury (Hg) to elucidate the cause(s) of these dramatic changes to earth biogeochemical cycles. In the Guandong section, South China, we observe anomalously low Hg concentrations and Hg to total organic carbon (Hg/TOC) ratios in the Late Sturtian BIFs, suggesting a period of limited continental volcanism during the Late Sturtian deglaciation. We hypothesize that instead of a major LIP event, long-lasting and subdued submarine volcanism slowly increased atmospheric CO2 to trigger the greenhouse climate that caused deglaciation. Negative shifts of ?199Hg in the studied section suggest that deglaciation was accompanied by atmospheric mercury depletion events (AMDEs). Extremely low TOC levels in the studied section may suggest low oceanic productivity, and this may support a non-biological cause of oceanic oxygenation during the Late Sturtian glaciation, through the release of photochemically produced H2O2 in melting glaciers.
Summary(Plain Language Summary, not published)
As part of GEM research a novel method of tracing the paleo-environmental mercury cycle has been developed. This has brought broad interest in applying these techniques to different major climate events through earth history. This paper examines the process of ocean oxidation towards the end of the PreCambrian that lead to evolution of modern life through tracing changes in the mercury cycle. Results provide new insight into the origin of life as we know it.

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