Neoarchean Era

What happens during this time?

Geophysical

• Continents as we know them today, with continental plates and plate tectonics appear

  • Subduction zones, continental plates sliding over each other, and upwelling of lava to produce new crust where continental plates tore apart

  • Continents grow by getting lighter and tougher

    • Cyclic re-melting and reformation of rock through lava flows (igneous differentiation) gradually separates the lighter minerals and allows the development of felsic rocks from mafic rocks.

    • Lighter rocks are more buoyant and resist recycling by floating over the liquid mantle.

  • The supercontinent Kenorland formed during the beginning of this period (~2.7 Ga)

• Methane gas is prominent, and oxygen mostly absent from the atmosphere

  • Subduction zones could have been a vital factor in the early oxygenation of the Earth (Meng et al., 2022)

• Oceans were probably green from rust, a ferrous–ferric hydroxy salt (Halevy et al., 2017)

Biological

• Evidence for the origin of oxygen-forming photosynthesis

  • Cyanobacteria probably use manganese (not water) as an electron source (Fischer, 2012)

  • Prokaryotic microbes may have been present on land as early as 2.75 billion years ago (Catling & Buick, 2012).

• Sulfur and molybdenum levels increased in the oceans around this time

• The simultaneous increase of both indicates that microbes on land may have been breaking down rock, which washed into the sea.