THE END-PERMIAN MASS EXTINCTION AND ITS AFTERMATH: INSIGHTS FROM NON-TRADITIONAL ISOTOPE SYSTEM

The end-Permian mass extinction (ca. 252 Mya) was by all measures the most severe biotic catastrophe in the history of animal life, marked by approximately 80% loss of marine animal genus diversity. The coincidence of mass extinction with Siberian Trap volcanism, carbon cycle perturbation, and ocean anoxia has been known for several decades. However, the magnitude and duration of environmental change and its role in shaping not only extinction but also subsequent reconstruction of marine ecosystems remain poorly quantified. Recently, the development of non-traditional isotope systems has enabled the development of new, high-resolution isotope proxy records that can be used to constrain and quantify the pattern and timing of changes in ocean redox and acid-base chemistry. Here we use evidence from calcium and uranium isotope measurements from marine stratigraphic sections in China and Turkey to demonstrate the global distribution of negative excursions in both δ⁴⁴Ca and δ²³⁸U across the end-Permian extinction horizon. Together, these observations place quantitative constraints on the magnitude and isotopic composition of carbon released into the exogenic carbon cycle during Siberian Trap volcanism as well as the extent and duration of resulting ocean anoxia. Moreover, continuing perturbation of the marine Ca and U isotope systems during Early Triassic time adds to existing evidence for influence of environmental change on the reconstruction of marine ecosystems. Coupled with increasingly precise geochronological evidence for synchrony between Siberian Traps volcanism and end-Permian extinctions, new constraints from non-traditional isotope proxies are helping us paint an increasingly detailed and quantitative picture of anoxic and temporarily acidified oceans during the biotic crisis. These findings suggest that the end-Permian mass extinction should be added to our growing catalogue of ancient analogs for 21^st and 22^nd century oceans.