Proxy evidence from the Gartnerkofel-1 core (Carnic Alps, Austria) for hypoxic conditions in the western Tethys during the end-Permian mass-extinction event

The most severe mass extinction in the Phanerozoic in the latest Permian Period (251.9 Ma), has been attributed to environmental effects related to the massive coeval Siberian flood-basalt eruptions. A potential causal link between the eruptions and the marine extinctions arises from lethal global warming from greenhouse-gas emissions and the resulting development of widespread hypoxic conditions in the warm oceans. The 331-m Gartnerkofel-1 core (Carnic Alps, Austria) penetrated the Permian-Triassic boundary interval in a western Tethys shallow carbonate-ramp setting. We calculated U/Th ratios and element-enrichment factors (for U, Cr, V, Co, and Ni) using the previously published raw elemental data from the core. These redox-sensitive proxy calculations provide evidence for an ~60-ky long episode of anoxic to euxinic ocean conditions in the shallow western Tethys at the time of the abrupt end-Permian mass extinction (EPME). Subsequent fluctuating dysoxic conditions were coincident with a negative excursion of δ¹³C_carb that is estimated to have lasted ~450 ky in the earliest Triassic at the GK-1 site. These findings in a high-deposition-rate section support previous reports of widespread anoxia in the western Tethys, and in the oceans in general, coincident with the EPME and its aftermath.