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Artigo
Síntese geológica e geocronológica do Cráton São Luís e do Cinturão Gurupi na região do Rio Gurupi (NE-Pará / NW-Maranhão)
The Gurupi region in northern Brazil has been divided into Paleoproterozoic (São Luís Craton) and Neoproterozoic (Gurupi Belt) geochronological domains based on Rb-Sr and K-Ar. Recent zircon (Pb evaporation) dating of most of the lithostratigraphic and lithodemic units, in addition to limited whole-...
Autor principal: | KLEIN, Evandro Luiz |
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Outros Autores: | MOURA, Candido Augusto Veloso |
Grau: | Artigo |
Idioma: | por |
Publicado em: |
2015
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Assuntos: | |
Acesso em linha: |
http://repositorio.ufpa.br/jspui/handle/2011/6438 |
Resumo: |
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The Gurupi region in northern Brazil has been divided into Paleoproterozoic (São Luís Craton) and Neoproterozoic (Gurupi Belt) geochronological domains based on Rb-Sr and K-Ar. Recent zircon (Pb evaporation) dating of most of the lithostratigraphic and lithodemic units, in addition to limited whole-rock Sm-Nd determinations, shows virtually all rock units (juvenile or reworked) formed between ~2.0 Ga and 2.2 Ga. A single granitoid shows a Neoproterozoic crystallization age (~0,55 Ga), and the Archean has been recorded only in inherited zircons and in protolith Sm-Nd model ages. The compositional, metamorphic, structural, geophysical and geochronological characteristics of the geological units supports the previous subdivision into two domains. However, they also reveal a common Paleoproterozoic evolution of both the Gurupi and São Luís domains. The Gurupi domain is characterized as a collisional orogen, whereas the São Luís domain shows accretionary characteristics, with both participating in the widespread Paleoproterozoic collage at 2.2 - 2.0 Ga. During the Neoproterozoic, the southern border of this region was affected by strong strike-slip shearing and very limited lithogenesis, reflecting the Brasiliano orogenic collage elsewhere and defining the presently observed relationship between the São Luís Craton and the Gurupi Belt. |