The Neoarchean (/ˌnɑːrˈkən/; also spelled Neoarchaean) is a geologic era within the Archaean Eon.

2800 – 2500 Ma
Neoarchean Graphical Timeline
-2800 —
-2780 —
-2760 —
-2740 —
-2720 —
-2700 —
-2680 —
-2660 —
-2640 —
-2620 —
-2600 —
-2580 —
-2560 —
-2540 —
-2520 —
-2500 —
Prokaryotic Microbes appeared on land
Events of the Neoarchean.
Axis scale: millions of years ago.
Proposed redefinition(s)2780–2420 Ma
Gradstein et al., 2012
Proposed subdivisionsMethanian Period, 2780–2630 Ma

Gradstein et al., 2012
Siderian Period, 2630–2420

Gradstein et al., 2012
Name formalityFormal
Alternate spelling(s)Neoarchaean
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Chronological unitEra
Stratigraphic unitErathem
Time span formalityFormal
Lower boundary definitionDefined Chronometrically
Lower boundary GSSPN/A
GSSP ratifiedN/A
Upper boundary definitionDefined Chronometrically
Upper boundary GSSPN/A
GSSP ratifiedN/A

The Neoarchean spans the period from 2,800 to 2,500 million years ago— the period being defined chronometrically and not referenced to a specific level in a rock section on Earth.

Complex lifeEdit

During this era, oxygenic photosynthesis first evolved, releasing an abundance of oxygen, that first reacted with minerals and afterward was free to react with greenhouse gases of the atmosphere, leaving the Earth's surface free to radiate its energy to space. This is known as the oxygen catastrophe which was to happen later in the Paleoproterozoic from a poisonous buildup of oxygen in the atmosphere, released by these oxygen-producing photoautotrophs, which evolved earlier in the Neoarchean.

Continental formationEdit

During this era, the supercontinent Kenorland formed at about 2,720 million years ago.[1]:316


  1. ^ Bozhko, N. A. (2011). "On Two Types of Supercontinental Cyclicity". Moscow University Geology Bulletin. 66: 313–322.

External linksEdit