abstract:Oceanic anoxic events or anoxic events occur when the Earth's oceans become completely depleted of oxygen (O2) below the surface levels. The similar term euxinia refers to anoxic conditions in the presence of hydrogen sulfide.
The black unit including a bioticextinction was caused byoceanicanoxicevent. Crisisthat deepwater keeled foraminifera encounteredrepresentsa ferociousanoxia in deepmarine environment .