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About 3.4 Ga ago voluminous calc-alkaline magmas represented by the granitoid gneisses of southern India were emplaced into a now poorly preserved non-continental crust. Unstable ensialic basins, initiated at about 3.0 Ga, were filled with volcanic and sedimentary rocks up to about 2.6 Ga. This basement-cover sequence was deformed at the close of the Archaean, first by northward accretion and thickening of several crustal slabs formerly separated by prisms of stable shelf sediments. Structures produced by this episode were refolded and dislocated by large N-S strike-slip shear belts, to impart intense, steep planar fabrics to large volumes of the crust. Fluids rich in CO₂, possibly derived from sedimentary material driven beneath the crustal slabs by the thickening mechanism, purged the deep crust of H₂O to form granulites. Upward migration of hot H₂O-rich fluids encouraged partial melting at intermediate crustal levels. These late-Archaean tectonic and thermal events began soon after the close of basin filling and extended possibly to 2.5 Ga. The close spatial and temporal relationships between immense dyke swarms and 1.7 to 1.2 Ga sedimentary basins are believed to reflect protracted thermal disturbance beneath the Archaean craton in the mid- to late-Proterozoic. Late-Proterozoic tectonism resulted in westward overthrusting and thermal reworking of Archaean crust and transcurrent shear belts which juxtaposed dissimilar Archaean blocks.