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| Paleozoic Famatinian Belt | |
|---|---|
| Name | Paleozoic Famatinian Belt |
| Region | Andes |
| Period | Paleozoic |
| Orogeny | Famatinian orogeny |
Paleozoic Famatinian Belt The Paleozoic Famatinian Belt is an extensive early Paleozoic orogenic belt in western Argentina associated with convergent margin processes during the Ordovician and Silurian, linked to the broader evolution of western Gondwana and the assembly of Pangea. This belt records interactions among microcontinents, oceanic basins, and magmatic arcs, and it preserves evidence for arc magmatism, sedimentary basins, and metalliferous systems that influenced later geological provinces such as the Sierras Pampeanas, Cordillera Oriental, and the Andes.
The Famatinian complex developed during the Cambrian–Devonian interval as part of plate-scale motions involving Laurentia, Baltica, Siberia, and the Gondwanan margin, with important ties to events like the Taconic orogeny and the Caledonian orogeny, and later overprinted during the Alleghanian orogeny and Variscan orogeny. Classic research by institutions such as the Servicio Geológico Minero Argentino and universities like the University of Buenos Aires and the National University of Córdoba integrated field mapping, geochronology from laboratories in Germany, United States, and France, and paleomagnetic studies from groups tied to NASA and CNRS projects.
The belt lies along the western margin of Gondwana adjacent to the Pampean orogeny domain and formed in response to subduction along an oceanic plate analogous to the paleogeographic Rheic Ocean, with plate interactions comparable to the later dynamics recorded in the Peruvian Andes and the Nazca Plate. Tectonic reconstructions involve comparisons to the Falkland Islands terrane, the Cuyania and Precordillera microcontinents, and connections proposed with the Oklahoma aulacogen and parts of Laurentia. Geochronological constraints using U–Pb dating, Ar–Ar dating, and isotopic work from IGME and international consortia place peak magmatism and deformation in the Ordovician, with regional metamorphism akin to episodes recorded in the Southern Alps.
Stratigraphic frameworks combine sedimentary successions of the Sierra de Famatina and adjacent ranges, including sequences of turbidites, limestones, shales, and volcaniclastic rocks correlated with the San Juan Formation and units studied by the Geological Society of America and the International Commission on Stratigraphy. Key lithologies include calc-alkaline volcanics, high-K granitoids, ophiolitic remnants comparable to exposures in the Seychelles and the High Atlas, and carbonate platforms resembling Ordovician deposits described in Morocco and Spain. Biostratigraphic ties use taxa documented by the Smithsonian Institution and regional museums to correlate trilobite and brachiopod assemblages with global stages.
Arc magmatism produced batholiths, volcanic centers, and porphyry systems investigated for links to metallogenic belts such as the Bolivian Tin Belt and the Cuyune Mining District, with ore studies by companies including BHP and Glencore and national agencies like Yacimientos Petrolíferos Fiscales. Metallogenic endowment includes important occurrences of polymetallic veins, porphyry-type copper, and associated gold, molybdenum, and silver mineralization, with deposit models drawing on comparisons to El Teniente, Chuquicamata, and the Rio Tinto district. Isotopic work (Sr–Nd–Pb) and fluid inclusion studies by teams from CSIC and SERNAGEOMIN elucidate magma sources and ore fluid evolution.
Structural analyses reveal fold-and-thrust belts, regional nappes, and penetrative fabrics mapped across the Sierras de Córdoba, Sierra de San Luis, and the Sierras Pampeanas, with kinematic studies referencing methods developed at ETH Zurich and Massachusetts Institute of Technology. Deformation phases include early arc-continent collision, middle crustal shortening producing thrust duplexes, and later reactivation during Andean transpressional events comparable to structures studied in California and the Japan Alps. Microstructural analyses, thermobarometry, and fabric studies by groups at University of Cambridge and University of Chile constrain pressure–temperature–time paths similar to those found in other Paleozoic belts.
Reconstructions place the belt on the western Gondwanan margin using data from paleomagnetic studies at Universidad Nacional de San Juan, paleobiogeographic ties to faunas in Antarctica and Australia, and correlations with tectonostratigraphic terranes like Peruvian Andes fragments. Models integrate evidence from the Gondwana Research community and tools developed at Paleomap Project and University of Texas at Austin to test scenarios linking the Precordillera to Laurentian elements and comparing the belt’s evolution to coeval systems in Avalonia and Armorica.
The belt hosts significant mineral resources that underpin mining in Argentina, attracting companies such as Barrick Gold, Pan American Silver, and national entities like Minera Alumbrera. Deposits include stratabound base-metal occurrences, structurally controlled gold-silver veins, and porphyry copper-molybdenum systems exploited in provinces including San Juan and La Rioja. Exploration and exploitation have economic ties to regional infrastructure projects funded by institutions like the Inter-American Development Bank and regulatory frameworks managed by the Secretariat of Mining.
Category:Geology of Argentina Category:Paleozoic orogenies