Arcaico: Diferenzas entre revisións

By the end of the Archaean c. 2600 Mya, plate tectonic activity may have been similar to that of the modern Earth. There are well-preserved sedimentary basins, and evidence of [[volcanic arc]]s, intracontinental [[rift]]s, continent-continent collisions and widespread globe-spanning [[Orogeny|orogenic events]] suggesting the assembly and destruction of one and perhaps several [[supercontinent]]s. Liquid water was prevalent, and deep oceanic basins are known to have existed by the presence of [[banded iron formation]]s, [[chert]] beds, chemical sediments and pillow basalts.

 

Although a few mineral grains are known that are Hadean, the oldest rock formations exposed on the surface of the [[Earth]] are Archean or slightly older. Archean rocks are known from [[Greenland]], the [[Canadian Shield]], the [[Baltic shield]], [[Geology of Scotland|Scotland]], [[Geological history of India|India]], [[Brazil]], western [[Geology of Australia|Australia]], and southern [[Africa]]. Although the first [[continents]] formed during this eon, rock of this age makes up only 7% of the world's current [[craton]]s; even allowing for erosion and destruction of past formations, evidence suggests that continental [[crust]] equivalent to only 5-40% of the present amount formed during the Archean.<ref>Stanley, pp. 301-2</ref>