The end-Triassic Mass Extinction (ETME, ~201.5 Ma) was driven by one of the most significant hyperthermal events of the Phanerozoic, likely linked to the emplacement of the Central Atlantic Magmatic Province (CAMP). Marine anoxia was suggested as the primary driver of the extinction. However, the geographic spread of low oxygen conditions and the precise temporal and mechanistic links between deoxygenation and extinction remain elusive. This study integrates new redox data from the Dove’s Nest borehole of the Cleveland Basin with data from other marine realms of the western Tethys. Our findings reveal that redox conditions were highly variable over time, as well as across different basins and water depths. Evidence of significant deoxygenation is observed across the Triassic-Jurassic boundary (2^nd extinction phase) at the majority of thereported sites in the western Tethys. Nonetheless, predominantly oxic conditions prevailed during the first phase of the ETME in the latest Rhaetian. These results suggest that driver of the initial phase of the ETME in certain European marginal seas were not solely the consequence of marine anoxia. Combined with results from climate modelling, our analyses further demonstrate that sea-level fluctuations and other climate-driven hydrological changes may have contributed to the earlier phase of the ETME.

marine redox changes, western Tethys, end-Triassic extinction