David Selby Paul C. Hackley Jeffrey Over Zeyang Liu 2020 <div class="article-section-wrapper js-article-section js-content-section "><p>The Devonian Period experienced significant fluctuations of atmospheric oxygen (O₂) levels (∼25–13%), for which the extent and timing are debated. Also characteristic of the Devonian Period, at the Frasnian–Famennian (F–F) boundary, is one of the “big five” mass extinction events of the Phanerozoic. Fossilized charcoal (inertinite) provides a record of wildfire events, which in turn can provide insight into the evolution of terrestrial ecosystems and the atmospheric composition. Here, we report organic petrology, programmed pyrolysis analysis, major and trace element analyses, and initial osmium isotope (Os_<i>i</i>) stratigraphy from five sections of Upper Devonian (F–F interval) from western New York, USA. These data are discussed to infer evidence of a wildfire event at the F–F boundary. Based on the evidence for a wildfire at the F–F boundary we also provide an estimate of atmospheric O₂<span>&nbsp;</span>levels of ∼23–25% at this interval, which is in agreement with the models that predict elevated<span>&nbsp;</span><i>p</i>O₂<span>&nbsp;</span>levels during the Late Devonian. This, coupled with our Os isotope records, support the currently published Os_<i>i</i><span>&nbsp;</span>data that lacks any evidence for an extra-terrestrial impact or volcanic event at the F–F interval, and therefore to act as a trigger for the F–F mass extinction. The elevated O₂<span>&nbsp;</span>level at the F–F interval inferred from this study supports the hypothesis that<span>&nbsp;</span><i>p</i>CO₂<span>&nbsp;</span>drawdown and associated climate cooling may have acted as a driving mechanism of the F–F mass extinction.</p></div> application/pdf 10.1130/B35457.1 en Geological Society of America Evidence of wildfires and elevated atmospheric oxygen at the Frasnian–Famennian boundary in New York (USA): Implications for the Late Devonian mass extinction article