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| Amazon Craton | |
|---|---|
| Name | Amazon Craton |
| Location | South America |
| Area | ~3,000,000 km2 |
| Period | Archean–Proterozoic |
| Lithology | granitoids, greenstone belts, metasediments |
| Namedfor | Amazon Basin |
Amazon Craton is a major Precambrian craton occupying large parts of Brazil, Bolivia, Peru, Colombia, Venezuela and Guyana. It underlies the modern Amazon River drainage basin and hosts Archean and Paleoproterozoic terranes that have been studied in the contexts of Plate tectonics, Supercontinent cycle, and South American geological evolution. Research on the craton integrates work by institutions such as the Brazilian Geological Service, US Geological Survey, University of São Paulo, Smithsonian Institution, and international collaborations involving the Geological Society of America and International Union of Geological Sciences.
The craton comprises ancient granitoid and gneiss complexes, greenstone belts, and metasedimentary sequences juxtaposed with mafic to ultramafic intrusions, ophiolitic remnants, and volcanic successions documented in field campaigns by teams from Universidade Federal do Pará, Universidade Federal de Ouro Preto, Carnegie Institution for Science, and Imperial College London. Exposed lithologies include tonalite–trondhjemite–granodiorite suites, calc-alkaline volcanics, komatiites, and banded iron formations that are comparable to assemblages in the Kaapvaal Craton, Pilbara Craton, Superior Province, and Laurentia. Structural fabrics record multiple deformational events correlated with shear zones, thrust belts, and granitoid emplacement associated with regional features like the Trans-Amazonian Orogeny and local provinces such as the Tapajós Province and Rio Negro-Juruena Province.
Models for assembly involve successive Archean nucleus growth and Paleoproterozoic orogenic accretion during the Transamazonian orogeny, the Sunsás Orogeny, and suturing events coeval with the assembly of Columbia and later Rodinia reconstructions proposed by researchers at Carnegie Institution and ETH Zurich. Tectonic scenarios invoke subduction, arc accretion, continental collision, and intracratonic reworking linked to neighboring shields such as the São Francisco Craton, the Guiana Shield, and the Congo Craton. Geodynamic interpretations reference plate reconstructions by groups at University of Texas at Austin, PaleoMAP Project, and Geoscience Australia.
Stratigraphic frameworks divide the craton into basement provinces and cover sequences including the Rondonian-San Ignacio Province, Rio Negro-Juruena Province, Southeast Amazonian Province, and the Guiana Shield margins, with Phanerozoic sedimentary overlays forming the Solimões Basin, Marajó Basin, and intracratonic basins studied by the Petrobras exploration teams and the Brazilian National Petroleum Agency. Correlation of metavolcano-sedimentary cycles, detrital zircon populations, and unconformities uses comparative datasets from the Piedmont Province, Mogok Metamorphic Belt, and basin studies undertaken by BP and TotalEnergies in Amazonian frontiers.
The craton hosts world-class mineralization including orogenic gold in the Tapajós Gold Province, iron ores in banded iron formations analogous to deposits in the Hamersley Province, manganese, copper porphyries, nickel sulfides, and significant bauxite, kaolinite, and phosphate occurrences exploited by companies such as Vale S.A., Anglo American, Kinross Gold, and Bechtel. Hydrocarbon potential in the craton-margin basins has attracted exploration by Petrobras, Repsol, and ExxonMobil, while gem deposits and alluvial diamonds have been examined in reports from the United Nations Development Programme and the World Bank.
U–Pb zircon, Sm–Nd, Lu–Hf isotopic studies, and Ar–Ar thermochronology by laboratories at University of Arizona, University of Cambridge, and Universidade Estadual de Campinas reveal Archean zircon cores (>3.4 Ga) and Paleoproterozoic overgrowths (2.2–1.8 Ga) related to magmatic pulses tied to the Trans-Amazonian Orogeny and later reworking during the Brasiliano orogeny. Metamorphic grades range from greenschist to granulite facies with high-pressure granulite and amphibolite facies metamorphism recorded in the Serrinha Block and Juruena Complex, constrained by multigrain and single-zircon analyses. Isotopic signatures inform crustal growth models and mantle-crust interaction comparable with studies on the Yilgarn Craton and Wopmay Orogen.
Paleogeographic reconstructions position the craton within supercontinents such as Kenorland, Columbia, Rodinia, and Gondwana, connecting to shields like the West Africa Craton, the Laurentia, and the Baltica during various Proterozoic episodes. Paleomagnetic, detrital zircon, and fossil distribution data from collaborations involving Paleomap Project, Smithsonian Institution, and Natural History Museum, London constrain southward drift, cratonic rotations, and margins that influenced Neoproterozoic glaciations recorded in peripheral basins and correlated with events like the Sturtian glaciation.
Exploration began with 19th-century surveys by expeditions linked to institutions such as the British Museum (Natural History), expanded through 20th-century mapping by the Brazilian Geological Service and multinational companies, and accelerated by modern airborne geophysics, detrital zircon geochronology, and geochemical mapping from teams at GEOTEM, CSIRO, USGS, and the European Space Agency. Contemporary research integrates remote sensing from Landsat, Sentinel-2, and geophysical datasets processed by centers including INPE and universities like Universidade Federal do Pará and Federal University of Goiás to advance mineral exploration and Earth-history reconstructions.