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Granite-greenstone terrains represent the main process by which continental crust was formed in the Archaean; the same process has continued since, at a diminishing rate. Granite plutonism added a layer about ten kilometres thick under the greenstones. From Early Archaean to Late Proterozoic, there was a progressive change in the volcanics; komatiites decreased from the Early Archaean, while the proportion of andesites and felsic volcanics increased. Continent-derived sediments, rare or absent from the Early Archaean, increased through time.
Tectonic deformation in the greenstone belts is separable into pre-diapiric, diapiric and post-diapiric. The first deformations were translational, mainly flat thrusts, the second compressional without crustal shortening, the third involved crustal shortening. Only the diapiric structures are an essential element of greenstone belt evolution but the others are generally important. The pre-diapiric and diapiric structures are related to subduction; the post-diapiric structures may be accretionary or collisional. Granite-greenstone terrains show only minor crustal thickening. Some adjacent high-grade terrains were intensely deformed, and the crust greatly thickened, by continent-continent collision.
