Crustal growth of the central-eastern Paleoproterozoic domain,SW Amazonian craton: Juvenile accretion vs. reworking |
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| Authors: | Moacir José Buenano Macambira Marcelo Lacerda Vasquez Daniela Cristina Costa da Silva Marco Antonio Galarza Carlos Eduardo de Mesquita Barros Julielson de Freitas Camelo |
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| Institution: | 1. Department of Earth and Environmental Sciences, BIUST, Botswana;2. Department of Geology, University of Johannesburg, South Africa;3. Korzhinskii Institute of Experimental Mineralogy RAS, Chernogolovka, Russia;4. Department of Petrology, Geological Faculty, Moscow State University, Russia;1. Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Sektion Geochronologie, GeoPlasma Lab, Königsbrücker Landstraße 159, 01109 Dresden, Germany;2. CEREGE, Aix-Marseille Université, Centre Saint-Charles, case 67, 3 place Victor Hugo, 13331, Marseille, France;3. Institut für Geowissenschaften, Mineralogie, Goethe Universität Frankfurt, Altenhoeferallee 1, 60438 Frankfurt, Germany;4. Department of Earth Sciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa;5. Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco;6. Centro de Geologia da Universidade de Lisboa (CeGUL), Faculdade de Ciências (FCUL), Departamento de Geologia (GeoFCUL), Campo Grande C6, 1749-016 Lisboa, Portugal;7. Directorate of Mining Development, Ministry of Energy, Mines, Water and Environment, Rabat, Morocco |
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| Abstract: | The Trans-Amazonian cycle was an important rock-forming event in South America, generating voluminous juvenile and reworked fractions of continental crust. The Bacajá domain, in the southern sector of the Maroni-Itacaiúnas Province in the Amazonian craton, is an example of the Trans-Amazonian terranes adjacent to the Archean Carajás block. Zircon Pb-evaporation and whole-rock Sm–Nd analyses were carried out on representative samples of six lithological units, and allowed the proposal of a comprehensive tectonic-magmatic evolutionary sequence for the central and eastern parts of this domain, from the Neoarchean to the Rhyacian. Gneisses with ages of ca. 2.67 and 2.44 Ga are the oldest rocks recorded in the region, and probably represent remnants of island and continental arcs. The Três Palmeiras succession, emplaced between 2.36 and 2.34 Ga, hosts gold deposits and represents the first record of Siderian supracrustal rocks in the Amazonian craton. It was probably part of an island arc/ocean floor accreted to a craton margin. Rhyacian granitogenesis lasted for ca. 140 My (2.22–2.08 Ga), marking different stages of the Trans-Amazonian cycle. The first stage is represented by continental arc granitoids formed by melting of Archean crust at 2.22–2.18 Ga. The second is characterized by the production of juvenile material between 2.16 and 2.13 Ga. The third and final stage at ca. 2.08 Ga is represented by a large volume of granitoids originated from either juvenile material or reworked crust during compressive stresses. Nd isotopes reveal that juvenile rocks dominated in the northern part of the domain, whereas those formed from reworked crust predominate in the south. The present-day configuration of the Bacajá domain results from collision against the Archean Carajás block at the end of the Trans-Amazonian cycle. |
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