Iron oxides in tropical soils on various parent materials
| Autor: | Anchalee Suddhiprakarn, Michael Smirk, Wanpen Wiriyakitnateekul, Robert Gilkes, Irb Kheoruenromne |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Basalt
Goethite Crystal chemistry Inorganic chemistry Oxide Mineralogy chemistry.chemical_element 020101 civil engineering 02 engineering and technology Hematite 010502 geochemistry & geophysics 01 natural sciences 0201 civil engineering chemistry.chemical_compound chemistry Geochemistry and Petrology Aluminium visual_art Soil water visual_art.visual_art_medium Crystallite Geology 0105 earth and related environmental sciences |
| Zdroj: | Clay Minerals. 42:437-451 |
| ISSN: | 1471-8030 0009-8558 |
| DOI: | 10.1180/claymin.2007.042.4.02 |
| Popis: | Twenty nine Fe oxide concentrates of Thai soils formed on basalt, sandstone, shale/limestone and granite were investigated. Goethite and hematite are relatively more abundant in granitic and basaltic soils, respectively. Values of Feo/Fedrange from 0.01 to 0.28 indicating that free Fe oxides are mostly crystalline.There are no systematic differences in unit-cell dimensions for goethite and hematite in soils on different parent materials. Mean crystallite dimensions calculated from the 110 reflections are greater for hematite than for goethite. Aluminium substitution varies from 8 to 24 mole% for goethite and from 4 to 17 mole% for hematite. The dehydroxylation temperature for goethite ranges from 285ºC to 320ºC. The goethite in basaltic soils has a smaller crystal size and Al substitution, as well as a lower dehydroxylation temperature, compared to soils on other parent materials. The dehydroxylation temperature of goethite is positively related to Al substitution (R= +0.58), MCD110 (R= +0.49) and Ald (R= +0.53). The Mn, Ni, Cr, V and P in these soils occur in Fe oxides rather than as discrete minerals. |
| Databáze: | OpenAIRE |
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