| 1/ Because the amount of radiogenic heat-elements (Uranium, Potassium, and Thorium) was 2 to 6 times larger in the Archaean.
2/ Phanaerozoic:400-600ºC, Archaean 700-1000ºC.
3/ A warmer geotherm makes the lithosphere mechanically weaker.
4/ Laterial variation in density causes horizontal gravitational forces?
5/ Because the lithospheric mantle was less dense therefore more buoyant than present day lithospheric mantle.
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6/ It spread in a direction perpendicular to convergence. This limits the amount of thickening and therefore the topography.
7/ The heat is trapped in the crust and the temperature increases. This is called the blanket effect.
8/ Because greenstones are in average more dense (2910 kg.m-3) that granites (2650 kg.m-3).
9/ Granites in domes, and greenstones (volcanic rocks) in basins.
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