Stratigraphic, isotopic, and geochronological record of a superposed proforeland basin in the eastern São Francisco craton during west Gondwana amalgamation.
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2020
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Resumo
The Três Marias Formation, a siliciclastic succession that occurs at the top of the Bambuí Group, has recorded the
filling of the Brasiliano foreland basin that developed on the São Francisco craton. At the eastern portion of this
craton, the Três Marias Formation outcrops in Gorutuba ridge, north of Minas Gerais, which area was investigated by using field work, stratigraphic analysis, and isotopic U–Pb and Lu–Hf analysis. In this area, the Três
Marias Formation includes molasse deposits composed mainly of arkoses and hybrid conglomerates. The arkose
sediments came into the basin through a fluvio–deltaic system located to the northeast and were reworked in a
siliciclastic shelf under the influence of waves, tides and storm currents. The paleocurrents indicate a coastline
around the NW and NE directions, with current flows reworking sediments parallel and transversal to the coast.
The detrital zircon grains indicate a 555 ± 17 Ma maximum age of the deposition for this unit, and its main
sources are related to granitoids from the pre-orogenic and pre-to syn-collisional stages of the Araçuaí orogen
(ca. 630–560 Ma). The filling of the foreland basin system created in response to the Araçuaí fold–thrust belt is
younger than the one existing in the occidental portion of Bambuí basin, which is related to the Brasília fold and
thrust belt. Therefore, the final filling of the Bambuí basin would have been controlled by the development of
these two-fold–thrust belts throughout the margins of the São Francisco craton during the assembly of West
Gondwana.
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Foreland basin, Bambuí group, Neoproterozoic
Citação
ROSSI, A. V. A. et al. Stratigraphic, isotopic, and geochronological record of a superposed proforeland basin in the eastern São Francisco craton during west Gondwana amalgamation. Journal of South American Earth Sciences, v. 97, p. 102406, jan. 2020. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0895981119304912>. Acesso em: 10 mar. 2020.