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TitleMajor volcanic eruptions linked to the Late Ordovician mass extinction: evidence from mercury enrichment and Hg isotopes
AuthorHu, D; Li, M; Chen, J; Luo, Q; Grasby, S EORCID logo; Zhang, T; Yuan, S; Xu, Y; Finney, S C; Sun, L; Shen, Y
SourceGlobal and Planetary Change vol. 196, 103374, 2020 p. 1-13,
Alt SeriesNatural Resources Canada, Contribution Series 20200593
Mediapaper; on-line; digital
File formatpdf; html
AreaNevada; Vinini Creek; Roberts Mountains; Eureka; Chongqing; Guiyang; Changsha; United States of America; China
Lat/Long WENS 109.1567 109.1572 28.5275 28.5269
Lat/Long WENS-116.2597 -116.2597 39.8758 39.8753
Subjectsgeochemistry; tectonics; environmental geology; Science and Technology; Nature and Environment; Upper Ordovician; extinctions, biotic; mercury geochemistry; isotopic studies; mercury; sulphur geochemistry; organic carbon; volcanism; paleoenvironment; paleogeography; bedrock geology; lithology; sedimentary rocks; limestones; black shales; geochemical anomalies; paleoclimates; Late Ordovician Mass Extinction; Laurentia; Phanerozoic; Paleozoic; Ordovician
Illustrationsdiagrams; tables; stratigraphic columns
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic, Pearya Terrane, North Ellesmere
Released2020 11 12
AbstractThe Late Ordovician mass extinction (LOME) was the second most severe Phanerozoic biodiversity crisis. While environmental deterioration and oceanographic changes associated with the Hirnantian glaciation have been frequently invoked as potential extinction drivers, recent evidence for a large igneous province eruption at that time has challenged this prevailing view. As such, the triggering and killing mechanisms of the LOME remain debated. Here we report mercury (Hg) concentrations, isotopic compositions, Hg/total sulfur (Hg/TS), and Hg/total organic carbon (Hg/TOC) in Late Ordovician limestone/black shale alternations from two successions in South China and Laurentia that straddled the paleoequator. Our results, in both areas, show multiple Hg enrichments before and during the LOME, suggesting a global, or at least a widespread increase in environmental Hg loading. The initial Hg enrichments occur in the mid-upper Katian units and are followed by additional Hg anomalies in the lower Hirnantian strata that coincide temporally with the first pulse of the LOME. Extremely high levels of Hg, Hg/TS, and Hg/TOC, with maximum values of 737 ng g-1, 633 ng g-1 Hg/wt% TS, and 167 ng g-1 Hg/wt% TOC, respectively, represent ~3-13 × background values, indicating increased Hg input to the ocean. The absence of mass-independent fractionation of Hg isotopes in the Hg-enriched intervals suggests a volcanic source for the observed Hg anomalies. The temporal coincidence of Hg anomalies with the extinction horizon in both continents suggests that extensive and widespread volcanism may have had global climatic and ecological impact, and was a primary trigger for prolonged and synergetic deterioration of Late Ordovician environment such as climate changes, ocean acidification, and anoxia, causing the LOME.
Summary(Plain Language Summary, not published)
This paper examines evidence for volcanism and associated climate warming as a driver for the Late Ordovician mass extinction.

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