First record of the early Toarcian Oceanic Anoxic Event in the Hebrides Basin (UK) and implications for redox and weathering changes

The early Toarcian (~183 Ma) was characterized by a prominent volcanism-induced warming event associated with massive addition of 12C-enriched carbon to the ocean-atmosphere system. This likely contributed marked ocean deoxygenation during this time, giving its name: Oceanic Anoxic Event (T-OAE). Although T-OAE has been recognized globally, clear geographic differences in character and environmental effects have noted. Here we present new isotope, element abundance organic geochemical data from lower succession on Isle Raasay, Scotland (Hebrides Basin, Northwest European Shelf). These provide first evidence Scotland. is generally enriched matter through interval, though redox-sensitive trace indicate that oxic-suboxic bottom water conditions prevailed, potentially interspersed ephemeral anoxic episodes. Our elemental contrast for persistent anoxia/euxinia nearby basins, emphasize how spatially variable dependent depth basin hydrography. Similarly, anoxia not prerequisite deposition organic-rich lithologies T-OAE. Sedimentological evidence, coupled inorganic data, indicates increased coarse-grained detrital flux enhanced chemical weathering findings support emerging strengthening hydrological cycling storminess at tropical subtropical latitudes globally response global