The Neoarchean (/ˌniːoʊ.ɑːrˈkiːən/ NEE-oh-ar-KEE-ən; also spelled Neoarchaean) is the last geologic era in the Archean Eon that spans from 2800 to 2500 million years ago—the period being defined chronometrically and not referencing a specific level in a rock section on Earth. The era is marked by major developments in complex life and continental formation.
>>>PUT SHARE BUTTONS HERE<<<
👉 Neoarchean in the context of Geological history of oxygen
Although oxygen is the most abundant element in Earth's crust, due to its high reactivity it mostly exists in compound (oxide) forms such as water, carbon dioxide, iron oxides and silicates. Before photosynthesis evolved, Earth's atmosphere had little free diatomic elemental oxygen (O2). Small quantities of oxygen were released by geological and biological processes, but did not build up in the reducing atmosphere due to reactions with then-abundant reducing gases such as atmospheric methane and hydrogen sulfide and surface reductants such as ferrous iron.
Oxygen began building up in the prebiotic atmosphere at approximately 2.45 Ga during the Neoarchean-Paleoproterozoic boundary, a paleogeological event known as the Great Oxygenation Event (GOE). The concentrations of O2 attained were less than 10% of today's and probably fluctuated greatly. Around 500Mya a second event known as the Neoproterozoic Oxygenation Event lead to oxygen levels similar or even higher than the present. The increase in oxygen concentrations had wide-ranging and significant impacts on Earth's geochemistry and biosphere. Detailed connections between oxygen and evolution remain elusive.
In this Dossier
Neoarchean in the context of Neoproterozoic oxygenation event
The Neoproterozoic Oxygenation Event (NOE), also called the Second Great Oxidation Event, was a geologic time interval between around 850 and 540 million years ago during the Neoproterozoic era, during which the oxygen concentration in Earth's atmosphere and oceans rose significantly. Taking place after the end to the Boring Billion, a euxinic period of extremely low atmospheric oxygen spanning from the Statherian period of the Paleoproterozoic era to the Tonian period of the Neoproterozoic era, the NOE was the second major increase in atmospheric and oceanic oxygen concentration on Earth, though it was not as prominent as the Great Oxidation Event (GOE) of the Neoarchean-Paleoproterozoic boundary. Unlike the GOE, it is unclear whether the NOE was a synchronous, global event or a series of asynchronous, regional oxygenation intervals with unrelated causes.
Neoarchean in the context of Eratosthenian
The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface that is not significantly eroded by subsequent impacts, but which also does not possess a ray system. The massive basaltic volcanism of the Imbrian period tapered off and ceased during this long span of lunar time. The youngest lunar lava flows identified from orbital images are tentatively placed near the end of this period.
Its equivalent on Earth consists of most of the Mesoarchean and Neoarchean eras (Archean eon), Paleoproterozoic and Mesoproterozoic eras (Proterozoic eon).