Fortalecimento litosférico neoarqueano

quarta-feira, janeiro 21, 2009

Geology, August 2008, v. 36, no. 8, p. 635-638, doi:10.1130/G25031A.1;
© 2008 Geological Society of America

Neoarchean lithospheric strengthening and the coupling of Earth's geochemical reservoirs

Patrice F. Rey1 and Nicolas Coltice2

1 EarthByte Group, School of Geosciences, The University of Sydney, New South Wales 2006, Australia

2 Laboratoire des Sciences de la Terre, Ecole Normale Supérieure de Lyon, Université de Lyon, CNRS UMR 5570, 69364 Lyon Cedex 07, France

This paper explores the secular evolution of the height of an isostatically balanced collisional mountain belt in the context of ongoing convergence. We show that until the Neoarchean, continents were unable to sustain topography >2500 m. During the Neoarchean the continental lithosphere evolved through a rheological threshold, allowing for the development of significant topography. The consequence of the strengthening of the continental lithosphere is fundamental for the coupling of the Earth's geochemical reservoirs. The Neoarchean was a period of global changes during which exogenic envelopes recorded major shifts in composition toward modern values. We propose that during the Neoarchean the exogenic envelopes, which were until then coupled to the mantle through hydrothermal processes and volcanism, also became coupled to the continental crust through relief-generating tectonics processes and erosion, hence changing the balance between mantle versus crustal interaction with the exogenic Earth.

Keywords: Archean • tectonics • geochemistry • erosion • Earth evolution • modeling

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