6. Environmental Context |
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| Authors: | Hervé Martin Philippe Claeys Muriel Gargaud Daniele Pinti Franck Selsis |
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| Institution: | (1) Laboratoire Magmas et Volcans, Université Blaise Pascal, Clermont-Ferrand, France;(2) DGLG-WE, Vrije Universiteit Brussel, Brussels, Belgium;(3) Observatoire Aquitain des Sciences de l’Univers, Université Bordeaux1, Bordeaux, France;(4) GEOTOP-UQAM-McGill, Université du Québec à Montréal, Quebec, Canada;(5) Centre de Recherche Astronomique de Lyon and Ecole Normale Supérieure de Lyon, Lyon, France |
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| Abstract: | On Earth, the Archaean aeon lasted from 4.0 to 2.5 Ga; it corresponds to a relatively stable period. Compared with today, internal Earth heat production was several times greater resulting in high geothermal flux that induced the genesis of rocks such as komatiites and TTG suites, which are no more generated on Earth since 2.5 Ga. Similarly, the details of plate tectonic modalities (plate size, plate motion rate, plate thickness, tectonic style, irregular crustal growth, etc...) were different of modern plate tectonics. Both atmosphere and ocean compositions have been progressively modified and the greater heat production favoured the development of hydrothermalism and therefore created niches potentially favourable for the development of some forms of life. Catastrophic events such as giant meteorite falls or world-sized glaciations drastically and suddenly changed the environment of Earth surface, thus being able to strongly affect development of life. Even if specialists still debate about the age of the oldest indubitable fossil trace of life, Archaean can be considered as having been extremely favourable for life development and diversification. |
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| Keywords: | Archaean continental growth atmosphere and ocean evolution meteoritic impacts glaciations young sun |
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