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Titre du document / Document title

Mineralogia das frações areia, silte e argila de sedimentos do grupo Barreiras no municipio de Aracruz, estado do Espirito Santo = Mineralogy of the sand, silt and clay fractions of Barreiras group sediments inaracruz, Espirito Santo state, Brazil

Auteur(s) / Author(s)

MELO V. F. (1) ; NOVAIS R. F. (2) ; SCHAEFER C. E. G. R. (2) ; FONTES M. P. F. (2) ; SINGH B. (3) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Departamento de Solos, Universidade Federal do Parana - UFPR. Rua dos Funcionários, 1540, Juvevê, CEP 80035-050 Curitiba (PR), BRESIL
(2) Departamento de Solos, Universidade Federal de Viçosa - UFV, CEP 36571-000 Viçosa (MG), BRESIL
(3) Department of Agricultural Chemistry and Soil Science. The University of Sydney, N.S.W. 2006, AUSTRALIE

Résumé / Abstract

To investigate the mineralogical variations with depth, 11 samples were collected down to 14 m, in an exposed sediment packet of the Barreiras Group in Aracruz, Espirito Santo, Brazil. The sand, silt and clay fractions were studied by X-ray diffraction, differential thermal analysis, thermogravimetry and electron microscopy. The total contents of Fe in the clay and silt fractions and Ti and Zr in the silt fraction were determined by ICP after fluoridric acid extraction. Clay and silt fractions were submitted to selective and sequential mineral extractions, to characterize and quantify their constituents. The sand fraction showed a uniform mineralogical composition, almost solely quartz, with small amounts of mica, anatase, kaolinite and iron aggregates. In the 2.1; 4.2 and 7.7 m depths, the occurrence of iron mottles with dark-red colour was observed. Silt fraction, as well, is constituted mainly by quartz, with stable kaolinite aggregates and hematite. The clay fraction showed a high proportion of kaolinite, reaching 950 g kg-1 at 14 m depth. The low contents ofFe in the sediments and the humid conditions of the Coastal Tablelands favored kaolinite concentration and removal of minerals, mainly Fe oxides. Contents of Goethite (main Fe oxide in the sediment) decreased with depth. The amount of low cristalinity material in the clay fraction is small, varying from 3.2 to 24.0 g kg-1 for ammonium oxalate extraction and from 0.6 to 3.5 g kg-1 for extraction with 0.5 mol L-1 NaOH, due to the high degree of development of the sediments. For the same reason, the mica contents in the clay and silt fractions were lower than 5.0 g kg-1. As observed for kaolinite, the mica content in the clay fraction increased with depth.

Revue / Journal Title

Revista brasileira de ciência do solo    ISSN  0100-0683   CODEN RBCSDP 

Source / Source

2002, vol. 26, no1, pp. 29-41 (1 p.1/4)

Langue / Language

Portugais

Editeur / Publisher

Sociedade Brasileira de Ciência do Solo, Campinas, BRESIL  (1977) (Revue)

Mots-clés anglais / English Keywords

oxides

;

silicates

;

sheet silicates

;

clay minerals

;

sedimentary rocks

;

clastic rocks

;

South America

;

soils

;

iron oxides

;

kaolinite

;

zirconium

;

titanium

;

iron

;

SEM data

;

thermogravimetric analysis

;

differential thermal analysis

;

X-ray diffraction

;

clay

;

silt

;

sand

;

Espirito Santo Brazil

;

Brazil

;

Mots-clés français / French Keywords

Oxyde

;

Silicate

;

Phyllosilicate

;

Argile minéral

;

Roche sédimentaire

;

Roche clastique

;

Amérique du Sud

;

Sol

;

Oxyde fer

;

Kaolinite

;

Zirconium

;

Titane

;

Fer

;

Donnée MEB

;

Analyse thermogravimétrique

;

Analyse thermique différentielle

;

Diffraction RX

;

Argile

;

Silt

;

Sable

;

Espirito Santo

;

Brésil

;

Mots-clés espagnols / Spanish Keywords

Óxido

;

Silicato

;

Filosilicato

;

Arcilla mineral

;

Roca sedimentaria

;

Roca clástica

;

America del sur

;

Suelo

;

Óxido de hierro

;

Caolinita

;

Zirconio

;

Titanio

;

Hierro

;

Dato MEB

;

Análisis térmico diferencial

;

Difracción RX

;

Arcilla

;

Limo

;

Arena

;

Espíritu Santo

;

Brasil

;

Localisation / Location

INIST-CNRS, Cote INIST : 18102, 35400010058189.0040

Nº notice refdoc (ud4) : 14155115



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