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| Patagonian Craton | |
|---|---|
| Name | Patagonian Craton |
| Type | Craton |
| Location | Patagonia, Argentina, Chile |
| Coordinates | 49°S 71°W |
| Age | Paleoarchean to Neoproterozoic |
| Lithology | Metamorphic basement, granitoids, greenstone belts |
| Notable exposures | North Patagonian Massif, Deseado Massif, Chonos Fold Belt margins |
Patagonian Craton
The Patagonian Craton is an ancient Precambrian continental block exposed in southern Argentina and Chile, forming a coherent basement massif beneath parts of Patagonia and contributing to the geology of the Southern Andes, the Falkland Islands continental fragment, and the southwestern margin of Gondwana. It records Archean to Neoproterozoic crustal growth and stabilization and has been studied in relation to major events such as the Grenville orogeny, the Pan-African orogeny, and the assembly of Pangea and Gondwana.
The craton comprises a mosaic of high-grade metamorphic terranes, granitoid plutons, and reworked greenstone sequences exposed in regions including the North Patagonian Massif, the Deseado Massif, and parts of the Chubut and Santa Cruz provinces. Research on the craton intersects work by institutions such as the Consejo Nacional de Investigaciones Científicas y Técnicas, the Universidad Nacional de La Plata, the Universidad de Buenos Aires, the Universidad de Chile, and international teams from the United States Geological Survey and the British Geological Survey.
The craton underlies a significant portion of southern South America and links to continental fragments studied in the Falkland Islands and offshore basins adjacent to the South Atlantic Ocean. Surface exposures include the North Patagonian Massif, the Deseado Massif, and relicts within the Chonos Fold Belt and the Aysén Region. Boundaries are defined by sutures that interact with terranes correlated to the Río de la Plata Craton, the São Francisco Craton, and the Antarctic Peninsula, and by Phanerozoic orogens like the Andean orogeny and the Sierra de la Ventana belt.
Basement lithologies record metamorphic and igneous assemblages comparable to those in the Kaapvaal Craton, the Yilgarn Craton, and the Superior Province with granitoids, gneisses, amphibolites, and greenstone remnants. Key structural domains include high-strain shear zones, crustal-scale fault systems, and deep seismic reflectors imaged by studies from groups at the Lamont–Doherty Earth Observatory, the GFZ German Research Centre for Geosciences, and the Institut de Physique du Globe de Paris. The crustal thickness and lithospheric mantle geometries have been constrained by seismic tomography and receiver function studies conducted by collaborations involving the IRIS Consortium, the Universidad de Concepción, and the CONICET.
Tectonic evolution spans Archean crustal accretion, Proterozoic reworking during the Brasiliano orogeny and possible links to the Rodinia supercontinent cycle, to Phanerozoic margin development during the Paleozoic and Mesozoic including interactions with the Famatinian orogeny, the Achalian orogeny, and later convergence associated with the Andean orogeny. Models invoke amalgamation through arc accretion, continent–continent collision, and extensional collapse related to breakup events leading to the opening of the South Atlantic Ocean. Paleomagnetic data from teams at the Instituto de Geofísica de México and the Scripps Institution of Oceanography have been used to test reconstructions involving the Gondwanaland assembly and dispersal.
The craton hosts mineral provinces including epithermal gold–silver systems in the Deseado Massif, porphyry copper–gold prospects related to Andean magmatism, and potential base metal and iron ore occurrences correlated with Proterozoic supracrustal packages. Exploration by companies such as Yamana Gold, Barrick Gold, Anglo American, Antofagasta plc, and the local arm of BHP has targeted mineralization along shear zones and intrusive contacts. Economic studies reference metallogenic models developed in comparison with deposits of the Sierra Madre Occidental, the Carajás Mineral Province, and the Kalahari Craton.
U–Pb zircon geochronology, Sm–Nd whole-rock isotopes, Lu–Hf zircon analyses, and Re–Os sulfide dating have constrained the timing of magmatism, metamorphism, and mineralization; key datasets come from laboratories at the Isotope Geochemistry Laboratory, University of Arizona, the University of Bern, and the Centro de Instrumentación Científica (CIC) of the Universidad de La Plata. Ages document Archean to Neoproterozoic basement formation, Mesoproterozoic reworking, and Paleozoic to Mesozoic magmatic events contemporaneous with regional provinces like the Sierras Pampeanas and the Patagonian Andes. Isotopic signatures have been compared against the Río de la Plata Craton and the Amazonian Craton to evaluate crustal growth versus reworking scenarios.
The craton’s margins record suturing with accreted terranes comparable to the Chilenia Block, the Sarmiento Metamorphic Complex, and correlations with the Precordillera Terrane. Its interactions with the Famatinian orogeny, the Paso del Sapo terrane accretion events, and the later Andean orogeny have influenced sedimentary basin development in the Neuquén Basin, the Magallanes Basin, and offshore hydrocarbon provinces targeted by energy companies like YPF and Shell. Comparative tectonics draw on analogs from the Caledonian orogeny and the Alleghanian orogeny to frame continental assembly and dispersal processes.
Category:Cratons Category:Geology of Argentina Category:Geology of Chile