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TitleMercury spikes suggest volcanic driver of the Ordovician-Silurian mass extinction
AuthorGong, Q; Wang, X; Zhao, L; Grasby, S E; Chen, Z Q; Zhang, L; Li, Y; Cao, L; Li, Z
SourceScientific Reports vol. 7, 5304, 2017, 7 pages,
Alt SeriesNatural Resources Canada, Contribution Series 20170079
Mediapaper; on-line; digital
File formatpdf
AreaYichang; China
Lat/Long WENS 100.0000 120.0000 32.0000 25.0000
Subjectsextinctions, biotic; mercury; marine sediments; volcanism; organic carbon; O-S extinction; Ordovician
Illustrationslocation maps; geological sketch maps; plots; stratigraphic charts
ProgramPearya Terrane, North Ellesmere, GEM2: Geo-mapping for Energy and Minerals
AbstractThe second largest Phanerozoic mass extinction occurred at the Ordovician-Silurian (O-S) boundary. However, unlike the other major mass extinction events, the driver for the O-S extinction remains uncertain. The abundance of mercury (Hg) and total organic carbon (TOC) of Ordovician and early Silurian marine sediments were analyzed from four sections (Huanghuachang, Chenjiahe, Wangjiawan and Dingjiapo) in the Yichang area, South China, as a test for evidence of massive volcanism associated with the O-S event. Our results indicate the Hg concentrations generally vary in parallel with TOC, and that the Hg/TOC ratios remain low and steady state through the Early and Middle Ordovician. However, Hg concentrations and the Hg/TOC ratio increased rapidly in the Late Katian, and have a second peak during the Late Hirnantian (Late Ordovician) that was temporally coincident with two main pulses of mass extinction. Hg isotope data display little to no variation associated with the Hg spikes during the extinction intervals, indicating that the observed Hg spikes are from a volcanic source. These results suggest intense volcanism occurred during the Late Ordovician, and as in other Phanerozoic extinctions, likely played an important role in the O-S event.
Summary(Plain Language Summary, not published)
As part of GEM research, GSC Scientists developed the use of mercury and mercury isotopes as a novel tool to trace major volcanic eruptions in the geologic past. This was applied to examine the cause of the second largest mass extinction in earth history (Late Ordovician Mass Extinction), which had no obvious driver. Results showed evidence for a major volcanic eruption at that time that is confirmed by stable isotope data showing large mercury spikes are derived from a volcanic source. This suggests that dramatic climate change driving by volcanic eruption was the overall driver for the mass extinction.