First record of the early Toarcian oceanic anoxic event from the Southern Hemisphere, Neuquén Basin, Argentina

The first record of the Early Toarcian Oceanic Anoxic Event (c. 183 Ma) from the Southern Hemisphere is described from the Neuquen Basin, Argentina, identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ13Corg) in bulk rock and fossil wood. The negative excursion of -6 per mil in bulk organic carbon (falling to -31.3 per mil) crosses the boundary of the tenuicostatum-hoelderi Andean ammonite Zones, equivalent to the tenuicostatum-falciferum/serpentinum zones of Europe. These data indicate that the Early Toarcian Oceanic Anoxic Event was a global phenomenon.