Journal of Geography (Chigaku Zasshi)
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
The 100s: Significant Exposures of the World (No. 1-3)
The Oldest Pillow Lavas, 3.8-3.7 Ga from the Isua Supracrustal Belt, SW Greenland
Plate Tectonics Had Already Begun by 3.8 Ga
Shigenori MARUYAMATsuyoshi KOMIYA
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2011 Volume 120 Issue 5 Pages 869-876


 The presence of pillow basalts in the 3.8-3.7 Ga Isua supracrustal belt, Southern West Greenland indicates the presence of liquid water on early Earth around 3.8-3.7 Ga. The total thickness of pillow basalts is up to 1.0 km for the thickest unit, suggesting an ocean depth of at least 1.0 km. The rigidity of the Early Archean oceanic lithosphere can be calculated from the petrologically estimated mantle potential temperature of 1450°C and ocean surface temperature below 100°C. The results show that the oceanic lithosphere was sufficiently rigid to operate modern-style plate tectonics only 0.7-0.8 Ga after the formation of the Earth.

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© 2011 Tokyo Geographical Society
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