The Proterozoic basement of Suriname consists of a greenstone-tonalite-trondhjemite-granodiorite belt in the northeast of the country, two highgrade belts in the northwest and southwest, respectively, and a large granitoid-felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U-Pb and Pb-Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2-1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.

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The Amazonian Craton, the core of the South American continent, consists of: (i) Archean nuclei, including the Carajás-Amapá areas in the southeast and the Imataca area in the northwest (3.0-2.5 Ga); (ii) the 1500-km long Trans-Amazonian greenstone-tonalite belt with associated granulite belts along much of the northern coast of the Guianas and northern Brazil (2.2-2.0 Ga); (iii) a Grenvillian orogenic belt along the westernmost part in southwestern Brazil (1.3-1.0 Ga); and (iv) a vast central part in which Paleoproterozoic and Mesoproterozoic granitoid and low-grade metavolcanic rocks predominate. Granitoid magmatism continued here almost uninterrupted between 2.0 Ga and 1.0 Ga, although cratonization was largely completed by 1.75 Ga. We argue that previous continental accretion models based on progressively younger granite ages westwards have to be revised in view of new geochronological data. Little-deformed sandstone platforms unconformably overlying older basement are widespread, and have been deposited in different episodes of post-orogenic basin formation from the Archean down to the Phanerozoic. Mafi c dykes of Proterozoic to Permo-Triassic age testify to various phases of extension, rifting and basin formation, including the formation of the Paleozoic basin system and the later Amazon drainage basin itself. Uplift and denudation since Gondwana break-up greatly increased sediment fl uxes towards the surrounding basins from the Mesozoic onwards.

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