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

Abstract

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 δ13Ccarb 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.