Periodic oceanic euxinia and terrestrial fluxes linked to astronomical forcing during the Late Devonian Frasnian–Famennian mass extinction

Oceanic anoxia is considered as the immediate cause of Frasnian–Famennian mass extinction, yet frequency and associated environmental modulators remains unknown. Here, we demonstrate that astronomical forcing paced oceanic anoxic episodes by mediating land-ocean interactions during Upper Kellwasser (UKW) Event, using an ultra-high-resolution (one centimeter spacing), multi-proxy geochemical profile a UKW interval from Devonian Chattanooga Shale Tennessee, USA. Organic inorganic indices for anoxia/euxinia, marine primary productivity, terrestrial plant/soil inputs, clastic sediment inputs show synchronous fluctuations were Earth's orbital precession. This study provides first mechanistic evidence linking periodicity Late euxinia to identifies terrestrial-to-marine organic fluxes driver this linkage. These results suggest modulated expression stressors led extinction.