Abstract Supergene lateritic deposits have played an important role in the global mineral resource economy for over 50 years, with lateritic Al, Fe, Ni, and Au deposits having a significant input to global metal production and reserves. Significant scientific research started in the 1970s, focusing initially on bauxites and, subsequently, on Ni laterites. In the 1980s, attention turned to Au, Fe, and Mn deposits with most research efforts focused on supergene Au deposits, because this also had implications for exploration of primary mineralization. Most recently, research has focused on the formation of lateritic P-Nb deposits. This paper reviews the knowledge acquired, mostly during the past two decades, on the processes of metal enrichment during lateritization. The first section deals with lateritic bauxite deposits. Three type of bauxitic profiles are distinguished: (1) orthobauxites, the product of a single weathering phase; (2) metabauxites, which are very aluminous and result from the transformation of orthobauxites due to a change to less humid conditions; and (3) cryptobauxites, which are bauxites concealed by a clay-rich cover, typical of highly humid Amazonian conditions. The bedrock and geomorphology also influence the formation of bauxite deposits. The second section presents a classification of Ni lateritic deposits, describing three principal types: (1) oxide deposits dominated by Fe oxyhydroxides, with Ni mainly hosted in goethite; (2) hydrous Mg silicate deposits, dominated by the Mg-Ni silicates “garnierite”in the saprolite; and (3) clay silicate deposits, dominated by Ni-rich smectites. Clay silicate deposits represent 5 to 10 percent of global resources, with the remainder divided about equally between hydrous Mg silicates and oxides. Controls on the formation of Ni lateritic deposits include bedrock lithology, tectonic setting, age of weathering, paleoclimatic history, and the geomorphology. Lateritic iron deposits can be divided in two subtypes: (1) residual lateritic iron ores, developed normally on banded iron formation but submitted to a lateritic weathering that increased the goethite content; and (2) the channel iron deposits. The latter formed by the accumulation of fluvial sediments, during the Tertiary, in paleochannels incised into a ferruginized surface of Precambrian bedrock. Lateritic gold deposits can be classified according to the distribution of Au in the profile, which is generally dependent on the paleoclimatic history of the regolith. In savanna environments, Au has mainly accumulated residually, although it is partly leached in the ferruginous duricrust. Most deposits appear to have been initially of this type but have been modified following climatic changes. In humid tropical rain forest regions, the duricrust becomes degraded and Au may be enriched in the upper ferruginous horizons of the saprolite. In semiarid environments, postlateritic remobilization has occurred through the dissolution of Au by acid and saline ground waters, resulting in Au enrichment deeper in the profile. Lateritic phosphate and niobium deposits form from apatite-rich carbonate rocks. There are two types, depending upon the bedrock, namely, sedimentary phosphate, developed from mainly marine carbonates; and igneous phosphates, derived essentially from carbonatites. The dissolution of carbonates under humid tropical climates causes a large volume reduction and residual accumulation of less soluble elements, forming very specific weathering profiles. Given the long time frames under which the deposits have formed and evolved and their wide distribution, the mechanisms of formation of lateritic deposits must be considered in a global perspective. This paper addresses the main features of the deposits and the lithological, geomorphological, and paleoclimatological processes that have led to their formation.

Abstract Current models for the tectonic evolution of northeastern South America invoke a Palaeogene phase of inter-American convergence, followed by diachronous dextral oblique collision with the Caribbean Plate, becoming strongly transcurrent in the Late Miocene. Heavy mineral analysis of Cretaceous to Pleistocene rocks from eastern Venezuela, Barbados and Trinidad allow us to define six primary clastic domains, refine our palaeogeographic maps, and relate them to distinct stages of tectonic development: (1) Cretaceous passive margin of northern South America; (2) Palaeogene clastics related to the dynamics of the Proto-Caribbean Inversion Zone before collision with the Caribbean Plate; (3) Late Eocene–Oligocene southward-transgressive clastic sediments fringing the Caribbean foredeep during initial collision; (4) Oligocene–Middle Miocene axial fill of the Caribbean foredeep; (5) Late Eocene–Middle Miocene northern proximal sedimentary fringe of the Caribbean thrustfront; and (6) Late Miocene–Recent deltaic sediments flowing parallel to the orogen during its post-collisional, mainly transcurrent stage. Domain 1–3 sediments are highly mature, comprising primary Guayana Shield-derived sediment or recycled sediment of shield origin eroded from regional Palaeogene unconformities. In Trinidad, palinspastic restoration of Neogene deformation indicates that facies changes once interpreted as north to south are in fact west to east, reflecting progradation from the Maturín Basin into central Trinidad across the NW–SE trending Bohordal marginal offset, distorted by about 70 km of dextral shear through Trinidad. There is no mineralogical indication of a northern or northwestern erosional sediment source until Oligocene onset of Domain 4 sedimentation. Paleocene–Middle Eocene rocks of the Scotland Formation sandstones in Barbados do show an immature orogenic signature, in contrast to Venezuela–Trinidad Domain 2 sediments, this requires: (1) at least a bathymetric difference, if not a tectonic barrier, between them; and (2) that the Barbados deep-water depocentre was within turbidite transport distance of the Early Palaeogene orogenic source areas of western Venezuela and/or Colombia. Domains 4–6 (from Late Oligocene) show a strong direct or recycled influence of Caribbean Orogen igneous and metamorphic terranes in addition to substantial input from the shield areas to the south. The delay in the appearance of common Caribbean detritus in the east, relative to the Paleocene and Eocene appearance of Caribbean-influenced sands in the west, reflects the diachronous, eastward migration of Caribbean foredeep subsidence and sedimentation as a response to eastward-younging collision of the Caribbean Plate and the South American margin. Supplementary material: Location maps and detailed heavy mineral data tables are available at http://www.geolsoc.org.uk/SUP18365.

Within the Amazonian Craton, Archean crust is restricted to the Carajás granite-greenstone terrain. The younger Maroni-Itacaiunas province, including supra-crustal sequences and associated calc-alkaline granitoids, is linked with the Birimian system in West Africa, making up a large Paleoproterozoic cratonic nucleus. Beginning at ca. 2.0 Ga, accretionary belts formed along the southwestern margin of this nucleus, giving rise to the Ventuari-Tapajós (2000–1800 Ma), Rio Negro–Juruena (1780–1550 Ma), and Rondonian–San Ignacio (1500–1300 Ma) tectonic provinces. Continued soft-collision/accretion processes driven by subduction produced a very large “basement” in which granitoid rocks predominate, many of them with juvenile-like Nd isotopic signatures. Felsic volcanics are also widespread; however, there is no evidence of Archean basement inliers, and regions with high-grade metamorphics are restricted. The Sunsas-Aguapeí (1250–1000 Ma) orogenic belt, at the southwestern end of the craton, was originated in an extensional environment, later deformed during the Grenvillian collision between Amazonia and Laurentia. Over the cratonic area, a widespread anorogenic granitic magmatism (1000–970 Ma) is a reflection of this orogeny over the stable foreland. After the termination of the Sunsas orogeny, continental fragmentation affected the eastern margin of the Amazonian Craton. The intra-oceanic Goiás magmatic arc, closely associated with the Transbrasiliano megasuture, is the evidence of a large oceanic domain that started its consumption between 900 and 800 Ma, giving rise to juvenile material represented by calc-alkaline orthogneisses. Later, these units were deformed during the Brasiliano orogeny (700–500 Ma), in the process of amalgamation of Gondwana.