603-pp9 - Archean Eoarchean: 3.8 - 3.6 Ga Archean Oceans...

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1 Archean Oceans Orin Robinson Archean • Eoarchean: 3.8 - 3.6 Ga – oldest known terrestrial rocks – possible beginning of formation of first supercontinent • believed to have existed as far back as 3.6 Ga – debatable geochemical evidence for life • not widely accepted Archean • Paleoarchean: 3.6 - 3.2 Ga – evidence for the first stromatolites – formation of the first stable crusts • still being debated http://www.wmnh.com/wmel0000.htm Archean • Mesoarchean: 3.2 - 2.8 Ga – first widely accepted fossil evidence of life – banded iron formations www.amnh.org http://www.uwsp.edu/geo/faculty/hefferan/Geol106/ CLASS3/ARCHEAN%20LIFE.htm Archean • Neoarchean: 2.8 - 2.5 Ga – first large continental shields http://www.uwsp.edu/geo/faculty/hefferan/Geol106/CLASS3/archean_rocks.htm Archean Tectonics • Interior of the Earth was 3x hotter than today • Rapid formation and recycling of oceanic crusts • Many small plates and volcanic islands http://www.cotf.edu/ete/modules/msese/earthsysflr/cambrian.html
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This note was uploaded on 02/10/2012 for the course MAS 603 taught by Professor Haywick during the Fall '11 term at S. Alabama.

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603-pp9 - Archean Eoarchean: 3.8 - 3.6 Ga Archean Oceans...

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