Potassium-argon ages of alkaline rocks from southern Brazil

Amaral, Guilherme; Bushee, Jonathan; Cordani, Umberto G.; Kawashita, Koji; Reynolds, J. H.

doi:10.1016/s0016-7037(67)80041-3

Cited by 157 publications

(100 citation statements)

References 15 publications

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“…A Late Cretaceous age (85.0 ± 0.9 Ma) was obtained for syenites by Amaral et al (1967;recalculated by Sonoki and Garda, 1988). Eby and Mariano (1992) determined an age of 114 Ma using fission track analysis in apatite.…”

Section: Geological Settingmentioning

confidence: 92%

Gorceixite from Catalão, Goiás, Brazil: rietveld crystal structure refinement

Ferrari

Toledo

Atencio

2007

Geol. USP, Sér. cient.

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Gorceixite is an abundant aluminum phosphate in Brazilian laterite phosphate ores and is one of the most important gangue minerals. Catalão I mine, Goiás, Brazil, one of the biggest phosphate mines in Brazil, contains great amounts of gorceixite, whose structural formula, as suggested by microprobe analysis, is (Ba 0.76 6.02 . Its crystal structure, rich in Ca, Sr, and Fe, was refined by the Rietveld method applied to X-ray powder diffraction data for trigonal and monoclinic structural models. The statistical parameters for the two models are so similar that they do not allow clear distinction of which is the better structural model for gorceixite. The cell parameters obtained for the trigonal model, space group R3m, are a = 7.0791 (3) Palavras-chave: gorceixita, estrutura cristalina, refinamento Rietveld, difração de raios X. RESUMOGorceixita é o mais abundante dos fosfatos aluminosos encontrados nos minérios fosfáticos lateríticos brasileiros, sendo um dos principais minerais de ganga destes minérios oxidados. A jazida de Catalão I (GO), uma das maiores do Brasil, contém grande quantidade de gorceixita, cuja fórmula estrutural sugerida pelos resultados de análises por microssonda eletrônica é (Ba 0,76 6,02 . Sua estrutura cristalina, rica em Ca, Sr, e Fe, foi refinada pelo método de Rietveld aplicado aos dados de difração de raios X, considerando tanto a estrutura monoclínica, quanto a trigonal. Os parâmetros estatísticos para ambos os modelos são muito similares e não permitem discriminar qual o melhor modelo de estrutura. Os resultados dos parâmetros de cela para o modelo trigonal, grupo espacial R3m, são: a = 7,0791(3) Å, c = 17,089(1) Å, V = 741,68(7) Å , Z = 2. A gorceixita de Catalão apresenta Fe substituindo Al na posição do sítio X e pequenas distorções nos diferentes sítios cristalinos. Estas características podem alterar as propriedades físico-químicas dos minerais que as contêm, como densidade e capacidade de fixação de metais pesados.

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Section: Geological Settingmentioning

confidence: 92%

Gorceixite from Catalão, Goiás, Brazil: rietveld crystal structure refinement

Ferrari

Toledo

Atencio

2007

Geol. USP, Sér. cient.

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“…Based on the integration of paleontological data (Gobbo-Rodrigues, 2001;Dias-Brito et al, 2001;Santucci & Bertini, 2001;Martinelli et al, 2011;Fragoso et al, 2013), stratigraphic information (Batezelli, 2015), as well as correlations with tectonic and magmatic events (Amaral et al, 1967;Hasui & Cordani, 1968;Sonoki & Garda, 1988;Machado Junior, 1992) that occurred in the northern and northeastern portions of the Bauru Basin, a Maastrichtian age is admitted for the Marília Formation. The outcrops of the Marilia Formation are densely bioturbated and cemented, resulting in the almost total obliteration of many sedimentary structures.…”

Section: Geological Settingmentioning

confidence: 99%

Freshwater Decapoda trace fossils in floodplain paleosols of Marilia Formation in Minas Gerais State (SE Brazil)

Nascimento¹,

Batezelli²,

Ladeira³

2017

Rev. bras. paleontol.

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-The Marilia Formation (Bauru Group, Bauru Basin) is an important record of the Upper Cretaceous in Brazil, and hosts an important fossil content. However, works regarding continental ichnology in this unit are still scarce. In order to improve this knowledge, the present work describes the occurrence of Camborygma litonomos in paleosols developed from floodplain deposits of the Marilia Formation in the Minas Gerais State. This trace fossil is associated with the activity of freshwater crayfishes, digging the soil looking for protection and to avoid the carapace dryness. Crayfish body fossils have not yet been described in deposits of the Bauru Group, thus, the trace fossil here recorded is the exclusive evidence of this organism, which is of great importance to the knowledge of the invertebrates paleodiversity of the Marilia Formation during the Late Cretaceous.

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“…Por outro lado, os corpos alcalinos reconhecidamente do Cretáceo Superior, como Cananéia (Amaral et al, 1967;Sonoki e Garda, 1988;Spinelli et al, 2001), Barra do Teixeira e Mato Preto (Amaral et al, 1967;Sonoki e Garda, 1988), ainda que dentro da área geográfica do Arco de Ponta Grossa, foram incluídas por Riccomini et al (2005) dentro do chamado "setor central" da Província da Serra do Mar, enquanto o complexo de Lages (integrando a então Província de Santa Catarina de Almeida, 1983) colocado junto ao seu "setor meridional".…”

Section: Série Científicaunclassified