Produção Nacional
Tectonic control of mesozoic mafic and alkaline bodies in the Amazon Craton (Brazil)
1991; Issue: 10 Linguagem: Inglês
10.11606/issn.2317-8078.v0i10p44-48
ISSN2317-8078
AutoresMário Ivan Cardoso De Lima, Pedro Édson Leal Bezerra,
Tópico(s)Geochemistry and Geologic Mapping
ResumoThe Amazon Craton unelerwent signiflcant tectonomagmatic activity during Mesozole time, markeel by dykes swarms, sllls, laecollths, anel flows of mafic volcanics and stocks of alkallne bodles.Thls event affecteel the entlre South American Platform anel is essentially relateel to tectonlc processes whlch resulteelln the formatlon of the Atlantlc Oceano A geotectonic scheme of the Amazon Craton (Brazilian portion), baseei on UMA (1984) is presenteei in Figure 1 anel shows the maflc dikes and alkallne magmatic aetivities of Mesozoic age.The Amazon Craton is a Brasiliano (Pan-African) entity, havlng been consolldated during the previous, Mlddle Proterozoic Uruaçuano Cycle.Truly Arehean nuclei crop out in southern Pará (Pau-d'Arco Nucleus) and northern Amapá (Oiapoque Nucleus).These terrains in the eastern Amazon region of Brazil were reworked during the Transamazonic Cycle due t~ the evo/ution of the Maroni-ltacalúnas (2,250-1,950 Ma) and Central Guyana (1,950-1,900 Ma) mobile belts, with NW-SE and NE-5W to ENE-WSW trends, respectively.Associated with these belts are shear zones with ultramy\onltes, my\onltes, pseudotachy\ltes, breceias and cataclasites, for example, the ltacaiúnas (ZBI), Tumucurnaque (ZBT), Mucajaf (ZBM), Anauá (ZBA), anel Parima (ZBP) shear zones.About 1,750-1,600 Ma ago the craton was affected by the evolution of the NW-SE orlenteel Rio Negro-Juruena mobile beIt wlth continental subductlon and collislon.Thls was followed 1,500-1,400 Ma ago (Uruaçuano Cycle) by development of the Rondoniano mobile belt and associated NW-5E orlented Jarnarl shear zone (ZBJ).Both of these geodynamic events were accompanied by
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