An anoxic event describes a period wherein large expanses of Earth's oceans were depleted of dissolved oxygen (O 2), creating toxic, euxinic (anoxic and sulfidic) waters. [1] Although anoxic events have not happened for millions of years, the geologic record shows that they happened many times in the past.

Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. [1] Anoxic waters can be contrasted with hypoxic waters, which

Dec 23, 2016 · Even today, the oceans are on the edge of anoxia: Every ocean basin has an oxygen minimum zone (OMZ) at a depth of a few hundred meters, where respiration consumes oxygen and depresses oxygen concentrations. Over large areas of the Eastern Pacific and the northern Indian Ocean, oxygen levels in the OMZ are close to zero.

Mar 9, 2010 · Oceanic anoxic events (OAEs) record profound changes in the climatic and paleoceanographic state of the planet and represent major disturbances in the global carbon cycle. OAEs that manifestly caused...

Nov 20, 2024 · The timing, tempo, and causative mechanisms of Ocean Anoxic Event 1a (OAE1a), one of several such abrupt perturbations of the Mesozoic global carbon cycle, remain uncertain. Mudstones interbedded with tuffs in Hokkaido, Japan preserve carbon and osmium isotope shifts recording OAE1a.

Oceanic anoxic events (OAEs) represent changes in global carbon cycle as well as biogeochemical cycles and are robust recorders of major changes brought in the ocean-atmosphere system of the Earth.

Jun 25, 2024 · Earth has endured multiple mass extinctions during its existence—the Toarcian Oceanic Anoxic Event (T-OAE), for example, decimated the planet’s marine ecosystems.

The second, larger pulse, the Toarcian Oceanic Anoxic Event (TOAE), was a global oceanic anoxic event, [9] representing possibly the most extreme case of widespread ocean deoxygenation in the entire Phanerozoic eon. [10] In addition to the PTo-E and TOAE, there were multiple other, smaller extinction pulses within this span of time. [8]

Jan 26, 2018 · During anoxic events, vast areas of the ocean become completely depleted of oxygen. Although humans have not experienced this phenomenon for millions of years, geological discoveries have established that our oceans have witnessed anoxic events multiple times.

Feb 13, 2023 · Here we present estimates of the global total anoxic and euxinic seafloor areas before and during the Toarcian Oceanic Anoxic Event based on rhenium and molybdenum enrichments, respectively,...