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Timing and provenance of volcanic fluxes around the Permian-Triassic Boundary Mass Extinction in South China: U-Pb zircon geochronology, volcanic ash geochemistry and mercury isotopes
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  • Oluwaseun Edward,
  • André N. Paul,
  • Hugo François Rudolf Bucher,
  • Christian Vérard,
  • Thierry Adatte,
  • Jeroen E. Sonke,
  • Urs Schaltegger,
  • Torsten Vennemann
Oluwaseun Edward
Institute of Earth Surface Dynamics, University of Lausanne

Corresponding Author:[email protected]

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André N. Paul
University of Geneva
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Hugo François Rudolf Bucher
Paläontologisches Institut der Universität Zürich
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Christian Vérard
University of Geneva
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Thierry Adatte
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Jeroen E. Sonke
Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université de Toulouse
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Urs Schaltegger
Université de Genève
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Torsten Vennemann
Universite de Lausanne
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Anomalous mercury (Hg) contents recorded near the Permian-Triassic boundary (PTB) are often linked to Siberian Traps Large Igneous Province (STLIP) volcanism and the Permian-Triassic boundary mass extinction (PTBME). However, mounting evidence indicates that the relation between STLIP volcanism and Hg “anomalies” is not straightforward. This study focuses on the timing and provenance of volcanic fluxes around the PTBME in South China. We constrain carbon isotope (δ13C) and Hg concentration and isotope records by utilizing high-precision U-Pb zircon ages from two expanded deep-water marine sections spanning the Late Permian to Early Triassic in the Nanpanjiang Basin. Results reveal two episodes of Hg enrichment. The oldest episode predates the onset of a large negative δ13C excursion, which is documented to be older than 252.07 ± 0.130 Ma. The second episode occurred between 251.822 ± 0.060 Ma and 251.589 ± 0.062 Ma, coinciding with the nadir of the δ13C excursion. Volcanic ash geochemistry and Hg isotope compositions suggest that mercury was sourced from subduction-related volcanic arc magmatism in the Tethys region, which peaked between 251.668 ± 0.079 Ma and 251.589 ± 0.052 Ma. These results are compatible with suggestions that regional arc volcanism contributed to the causes of the PTBME in South China and provide evidence that Hg anomalies close to the PTB are not a reliable stratigraphic marker for the PTB extinction event. This study demonstrates that the relations between volcanism, environmental perturbations and mass extinction during the Permian-Triassic transition are better resolved with the aid of high-precision U-Pb zircon ages.
14 Apr 2023Submitted to ESS Open Archive
16 Apr 2023Published in ESS Open Archive