Mercury chemostratigraphy across the Cambrian Series 2 – Series 3 boundary: evidence for increased volcanic activity coincident with extinction?
Faggetter, L.E.; Wignall, P.B.; Pruss, S.B.; Jones, D.S.; Grasby, S.; Widdowson, M.; Newton, R.J.
Dr Mike Widdowson M.Widdowson@hull.ac.uk
Lecturer in Volcanology and Geochemistry
Flood basalt volcanism represented by the Kalkarindji Province(Australia) is temporally associated with a trilobite mass extinction at the Cambrian Series 2 – Series 3 boundary, providing one of the oldest potential links between volcanism and biotic crisis in the Phanerozoic. However, the relative timing of flood basalt volcanism (Kalkarindji Province, Australia) and the trilobite extinctions, first recorded in North America, is not known. Mercury (Hg) enrichment in the sedimentary record provides a potential proxy for volcanism which may facilitate improved chronologies of eruption and extinction. Here we report mercury records for three sections from mid-shelf strata of the Great Basin (western USA) that straddle the Series 2 – Series 3 boundary. One section (Oak Springs Summit, NV) features a Hg enrichment at the start of the extinction interval, but mercury anomalies are also present at lower levels. These older anomalies may record either earlier phases of Kalkarindji volcanism, eruptions in other locations, or may be the result of sedimentary and/or diagenetic processes affecting the Hg record. In the Carrara Formation at Emigrant Pass, CA, the precise extinction horizon is not well defined, but a carbon isotope anomaly (the Redlichiid-Olenellid Extinction Carbon isotope Event; ROECE) provides a stratigraphic tie point to the Oak Springs Summit section. At Emigrant Pass, Hg enrichments precede the ROECE interval and are absent in the inferred extinction zone. The Pioche Formation at Ruin Wash, NV, lacks Hg enrichment at the extinction horizon but contains older enrichments. The inconsistent Hg records between the three sections demonstrate that factors controlling Hg accumulation and preservation in marine sedimentary environments are not yet fully understood. The effects of redox fluctuations may complicate one-to-one association of sedimentary Hg enrichments and massive volcanism at the Cambrian Series 2 – Series 3 boundary and elsewhere in the geologic record.
Faggetter, L., Wignall, P., Pruss, S., Jones, D., Grasby, S., Widdowson, M., & Newton, R. (2019). Mercury chemostratigraphy across the Cambrian Series 2 – Series 3 boundary: evidence for increased volcanic activity coincident with extinction?. Chemical Geology, 510, 188-199. https://doi.org/10.1016/j.chemgeo.2019.02.006
|Journal Article Type||Article|
|Acceptance Date||Feb 5, 2019|
|Online Publication Date||Feb 18, 2019|
|Publication Date||Apr 5, 2019|
|Deposit Date||Mar 14, 2019|
|Publicly Available Date||Apr 24, 2019|
|Peer Reviewed||Peer Reviewed|
|Keywords||Geology; Geochemistry and Petrology|
|Additional Information||This article is maintained by: Elsevier; Article Title: Mercury chemostratigraphy across the Cambrian Series 2 – Series 3 boundary: evidence for increased volcanic activity coincident with extinction?; Journal Title: Chemical Geology; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.chemgeo.2019.02.006; Content Type: article; Copyright: © 2019 Elsevier B.V. All rights reserved.|
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