Ontong Java Plateau eruption as a trigger for the early Aptian oceanic anoxic event

Abstract

The Early Cretaceous Ontong Java Plateau was emplaced at\nalmost the same time as marine biotic changes that culminated in oceanic\nanoxic event 1 (OAE1a). A causative link between these events\nhas been suggested, but direct evidence has been lacking until now.\nNew Os isotope measurements across the Lower Aptian “Selli Level”\nblack shale deposited during OAE1a in central Italy reveal two negative\nexcursions in marine 187Os/188Os ratios within a period of 2 Ma\nstarting above the Barremian-Aptian boundary and ending just above\nthe Selli Level horizon, suggesting an order-of-magnitude increase\nin the global fl ux of unradiogenic Os. The results are consistent with\nearly and major phases of eruption of the Ontong Java Plateau. The\nlatter phase is estimated to have been as short as ~1 Ma and may have\ninduced widespread oceanic stratifi cation that triggered OAE1a.