Significance Mass extinctions are major drivers of macroevolutionary change and mark fundamental transitions in the history of life, yet the feedbacks between environmental perturbation and biological response, which occur on submillennial timescales, are poorly understood. We present a high-precision age model for the end-Permian mass extinction, which was the most severe loss of marine and terrestrial biota in the last 542 My, that allows exploration of the sequence of events at millennial to decamillenial timescales 252 Mya. This record is critical for a better understanding of the punctuated nature and duration of the extinction, the reorganization of the carbon cycle, and a refined evaluation of potential trigger and kill mechanisms.

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High-precision geochronology confirms voluminous magmatism before, during, and after Earth’s most severe mass extinction.

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Mass extinction events are short-lived and characterized by catastrophic biosphere collapse and subsequent reorganization. Their abrupt nature necessitates a similarly short-lived trigger, and large igneous province magmatism is often implicated. However, large igneous provinces are long-lived compared to mass extinctions. Therefore, if large igneous provinces are an effective trigger, a subinterval of magmatism must be responsible for driving deleterious environmental effects. The onset of Earth’s most severe extinction, the end-Permian, coincided with an abrupt change in the emplacement style of the contemporaneous Siberian Traps large igneous province, from dominantly flood lavas to sill intrusions. Here we identify the initial emplacement pulse of laterally extensive sills as the critical deadly interval. Heat from these sills exposed untapped volatile-fertile sediments to contact metamorphism, likely liberating the massive greenhouse gas volumes needed to drive extinction. These observations suggest that large igneous provinces characterized by sill complexes are more likely to trigger catastrophic global environmental change than their flood basalt- and/or dike-dominated counterparts.