The Siberian Traps and the End-Permian mass extinction: A critical review

The association between the Siberian Traps, the largest continental flood basalt province, and the largest-known mass extinction event at the end of the Permian period, has been strengthened by recently- published high-precision [superscript 40]Ar/[superscript 39]Ar dates from widespread localities across the Siberian province[1]. We argue that the impact of the volcanism was amplified by the prevailing late Permian environmental conditions—in particular, the hothouse climate, with sluggish oceanic circulation, that was leading to widespread oceanic anoxia. Volcanism released large masses of sulphate aerosols and carbon dioxide, the former triggering short-duration volcanic winters, the latter leading to long-term warming. Whilst the mass of CO[subscript 2] released from individual eruptions was small compared with the total mass of carbon in the atmosphere-ocean system, the long ‘mean lifetime’ of atmospheric CO[subscript 2], compared with the eruption flux and duration, meant that significant accumulation could occur over periods of 10[superscript 5] years. Compromise of the carbon sequestration systems (by curtailment of photosynthesis, destruction of biomass, and warming and acidification of the oceans) probably led to rapid atmospheric CO[subscript 2] build-up, warming, and shallow-water anoxia, leading ultimately to mass extinction.