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| Arequipa-Antofalla | |
|---|---|
| Name | Arequipa-Antofalla |
| Type | Geological province |
| Region | Andes |
| Country | Peru, Bolivia, Argentina, Chile |
| Period | Neoproterozoic, Paleozoic, Mesozoic |
| Lithology | granitic rock, metasedimentary rock, volcanic rock |
| Namedfor | Arequipa, Antofagasta |
Arequipa-Antofalla is a regional cratonic and orogenic domain in the central Andes spanning parts of Peru, Bolivia, Argentina, and Chile. The province links major tectonic elements such as the Altiplano, the Central Volcanic Zone, and the Puna de Atacama and is bounded by suture zones associated with episodes recorded during the Pan-African orogeny, the Famatinian orogeny, and the Andean orogeny. It has been the focus of multidisciplinary studies involving researchers connected to institutions like the Smithsonian Institution, the U.S. Geological Survey, and the Consejo Nacional de Investigaciones Científicas y Técnicas.
The Arequipa-Antofalla domain comprises a mosaic of Precambrian to Mesozoic terranes that include craton fragments, continental margin sequences, and accreted island-arc remnants linked to events such as the Gondwana assembly and breakup, the Cuyania terrane accretion, and the closure of the Paleotethys Ocean. Major cities and research centers proximate to the province include Arequipa, Antofagasta, La Paz, and Salta, and regional infrastructure such as the Transandean Railway and the Pan-American Highway traverse its periphery. The domain's tectonostratigraphic architecture influences active magmatism in the Central Volcanic Zone and mineralization associated with belts like the Bolivian Tin Belt and the Peruvian Metallogenic Province.
Arequipa-Antofalla occupies a key position between the eastern Amazonian craton and the western Orogenic belt of the Andean orogeny, interfacing with notable structures such as the Cusco fold-and-thrust belt, the Coastal Cordillera, and the Sub-Andean foreland basins. The region records subduction-related processes linked to the Nazca Plate and the South American Plate convergence and archives signatures of plate reorganizations contemporaneous with the Paleo-Pacific Plate motions and the opening of the South Atlantic Ocean. Tectonic maps commonly show sutures comparable to the Pampean orogeny and terrane boundaries analogous to the Chilenia terrane and the Peruvian terrane.
Stratigraphic columns in the province contain sequences from the Neoproterozoic to the Mesozoic including metasedimentary successions correlated with the Belt Supergroup-style sequences, bimodal volcanic assemblages comparable to the Columbia River Basalt Group in scale analogues, and coeval plutonic suites reminiscent of the Sierra Nevada batholith. Dominant lithologies include high-grade mylonite, migmatite, and granodiorite bodies intruding pelitic-schist and psammitic units, with localized evaporite horizons and carbonate platforms that are comparable to Punta del Este Formation facies. Aeromagnetic and gravity surveys delineate intrusive complexes similar to the Maggie Hayes pluton and metamorphic domes akin to the Sierra de Córdoba.
The province's history begins with Neoproterozoic rifting and passive-margin sedimentation during events associated with the breakup of Rodinia and the assembly of Gondwana, followed by Ordovician-Silurian deformation during the Famatinian orogeny and later reworking during the Hercynian-equivalent episodes. Mesozoic extension related to the opening of the South Atlantic Ocean and westward subduction culminated in the development of the Andean magmatic arc and uplift during the Cenozoic Andean orogeny, producing modern topography shared with the Altiplano-Puna volcanic complex and influencing Neogene basins such as the Salta Basin. Episodes of crustal shortening are recorded in thrust systems analogous to the Sierras Pampeanas and in strike-slip faulting comparable to the Liquiñe-Ofqui Fault Zone.
Arequipa-Antofalla hosts significant mineralization types including high-sulfidation epithermal systems reminiscent of deposits in Yanacocha, porphyry copper-gold systems paralleling Escondida and Chuquicamata, and tin-polymetallic deposits analogous to the Bolivian Tin Belt occurrences in the Oruro region. Metallogenic processes are linked to magmatic arcs and hydrothermal circulation influenced by structures comparable to the Atacama Fault System and the Vicuña-Puquios Fault. Economic geology exploration often involves companies such as Barrick Gold, Newmont, BHP, and national entities like Servicio Nacional de Geología y Minería.
Fossil assemblages in sedimentary basins associated with the province document Neoproterozoic microbial mats comparable to Ediacaran biota, Paleozoic trilobite and brachiopod faunas akin to collections from the Famatina and Precordillera regions, and Mesozoic vertebrate remains paralleling finds from the Neuquén Basin and the Ischigualasto Formation. Trace fossils and ichnofabrics occur in shallow-marine carbonate sequences related to global events such as the Great Ordovician Biodiversification Event and Permian mass extinction intervals recognized in the Karoo Basin.
Scientific investigation of the Arequipa-Antofalla province has involved collaborations among institutions including the Universidad Nacional de San Agustín de Arequipa, Universidad de Chile, Instituto de Geología y Recursos Minerales, and international groups from the British Geological Survey and Institut de Physique du Globe de Paris. Mapping campaigns have produced regional maps comparable in scope to projects by the Geological Survey of Argentina and the USGS and have incorporated methods such as U–Pb zircon geochronology, detrital zircon provenance studies analogous to work on the Laurentia-to-Gondwana connections, isotopic systems like Sr–Nd–Pb tracing, and seismic imaging parallel to studies across the Andean Seismic Belt.