Evidence for volcanism and weathering during the Permian-Triassic mass extinction from Meishan (South China) osmium isotope record

The Permian–Triassic mass extinction event is the most severe biotic crisis during the Phanerozoic. The trigger of this event has been widely linked with massive volcanic activity associated with the Siberian Traps Large Igneous Province. However, the direct link is still lacking to fully understand the event. In this study, we apply osmium isotope (187Os/188Os, or Osi) stratigraphy across the Permian–Triassic boundary interval in the Meishan section of South China. The Os isotope stratigraphy reveals multiple shifts to more unradiogenic 187Os/188Os composition that are interpreted to reflect pulses of volcanism across the mass extinction interval. Additionally, a shift to a more radiogenic 187Os/188Os composition is also found immediately above the mass extinction interval, which is taken to reflect the enhanced weathering of the continental crust in response to greenhouse gas release into the atmosphere and the associated hyperthermal. •Presented is Os isotope stratigraphy of the Meishan Permian–Triassic interval.•Multiple unradiogenic Os isotope shifts are suggested to reflect pulses of volcanism.•A radiogenic Os isotope excursion is found above the mass extinction interval.•The radiogenic Os isotope shift may indicate enhanced weathering of the continent.