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TitleX-ray diffraction and infrared characterization of oxisols from central and southeastern Brazil
AuthorNitzsche, R P; Percival, J BORCID logo; Torrance, J K; Stirling, J A R; Bowen, J T
SourceClay Minerals vol. 43, no. 4, 2008 p. 549-560,
Alt SeriesEarth Sciences Sector, Contribution Series 20080634
PublisherMineralogical Society
Mediapaper; on-line; digital
File formatpdf
AreaMinas Gerais; Goiás; Sãn Paulo; Brazil
Lat/Long WENS-49.2500 -43.0000 -18.4167 -23.0000
Subjectsgeochemistry; x-ray diffraction; x-ray diffraction analyses; magnetite; goethite; hematite; maghemite; infrared spectral analyses
Illustrationsgeochemical analyses
Released2018 07 09
AbstractEleven Oxisols with high clay contents, 2.6-59.7 wt.% Fe2O3, and containing hematite, goethite, magnetite and maghemite, from São Paulo, Minas Gerais and Goia´s, Brazil, were studied for the purpose of microwave remote sensing applications in the 0.3 to 300 GHz range. Of special interest are: the pseudosand effect caused by Fe oxide cementation of clusters of soil particles; the mineralogy; and whether the soil magnetic susceptibility affected by ferromagnetic magnetite and maghemite interferes with microwave propagation. Quantitative mineralogical analyses were conducted using X-ray diffraction with Rietveld refinement. Visible, near infrared and
short wave infrared spectroscopic analyses were used to characterize the samples qualitatively for comparison with published spectral radiometry results. Quartz (3-88%), hematite (2-36%) and gibbsite (1-40%) occurred in all soils, whereas kaolinite (2-70%) and anatase (2-13%) occurred in nine samples. Ilmenite (1-8%) was found in eight soils and goethite (2-39%) in seven. Of the ferromagnetic minerals, maghemite occurred in seven soils (1-13%) and three contained magnetite (<2%). These results will be applied to the interpretation of the effect of Fe oxides, particularly the ferromagnetic oxides, on microwave interaction with high-Fe soils, with ultimate application to the monitoring of soil water content by microwave remote sensing.

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