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Beyond Earthly Skies

Life and the Formation of Continents

19 Jul 2014, 22:00 UTC
Life and the Formation of Continents
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On Earth, the presence of life plays a major role in determining the chemistry of the atmosphere and oceans. A study by D. Höning et al. (2014) suggests that the presence of life may play an even deeper role in influencing the planet’s evolution. In particular, the presence of life can enhance continental weathering rates, thereby increasing the rates at which sediments wash into and settle on the bottom of the oceans. These sedimentary layers hold within them a significant amount of water and hydrated minerals. Along convergent plate boundaries, the oceanic crust gets subducted into the Earth’s mantle, bringing along the water-rich sedimentary layers. As the subducting oceanic crust dives deeper, the increasing lithostatic pressure squeezes free water out from the sedimentary layers in a process known as shallow dewatering.The enhanced continental weathering rates due to the presence of life would lead to thicker sedimentary layers, and consequently, increase the amount of water being subducted. In addition, the enhanced continental weathering rates would reduce the amount of shallow dewatering due to a greater abundance of low-permeability deposits such as clay-rich deposits in the sedimentary layers. These low-permeability deposits effectively ‘seal off’ water entailed in the sedimentary layers from being ...

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