A Toarcian Ocean Anoxic Event record from an open-ocean setting in the eastern Tethys: Implications for global climatic change and regional environmental perturbation

The Early Toarcian “Oceanic Anoxic Event” (T-OAE) is recorded by marked disruption to both the climate system and marine ecosystems. Here, we present intergraded high-resolution carbon-isotope data (δ13C), bulk geochemistry, mineral characterization from an open-ocean setting in the eastern Tethys. With these data, we (1) construct the high-resolution record of the T-OAE from an open-ocean setting in the eastern Tethys; (2) show that the T-OAE in the Sewa succession was marked by coarser-grained deposits associated with high-energy conditions within the otherwise low-energy claystone deposits that likely linked to a globally increased supply of clastic sediments into marginal and deeper marine basin; (3) propose that the low Corg:Ptotal ratios, in combination with bioturbated structure and depletion or slight enrichment in redox-sensitive trace elements of V, Mo, and U suggest a long-term oxygenation event throughout the T-OAE interval at the Sewa succession, and hence, anoxia may not play a fundamental role during the Toarcian negative CIE in this setting; (4) exhibit that a warming and more humid climate began at the start of the T-OAE, and many episodic changes in sediment provenance throughout the T-OAE interval occurred at this location; and (5) suggest that accumulation of organic-matter sediments during the T-OAE is generally controlled by global climatic changes, but a regional environmental perturbation also might influence the preservation of organic matter.