The chemistry of weathering
| Autor: | Daniel Nahon, Jean-Jacques Trescases, Anicet Beauvais |
|---|---|
| Přispěvatelé: | Drever, J.I. (ed.) |
| Rok vydání: | 1985 |
| Předmět: |
Birnessite
ALTERATION Metamorphic rock Geochemistry GITOLOGIE Mineralogy Weathering engineering.material ROCHE METAMORPHIQUE COMPOSITION CHIMIQUE MINERALOGIE MANGANESE chemistry.chemical_compound LATERITISATION Todorokite chemistry GEOCHIMIE Laterite engineering Cryptomelane Parent rock Chlorite Geology |
| Zdroj: | The Chemistry of Weathering ISBN: 9789401088558 Scopus-Elsevier |
| DOI: | 10.1007/978-94-009-5333-8_16 |
| Popis: | Laterite profiles developed on manganiferous metamorphic rocks in the Ziemougoula area (North West Ivory Coast) permit the observation of chemical weathering of tephroites, manganocalci tes, chlorites and spessartite garnets. Several stages are observed in the progress of weathering. In the lower part of prof files, tephroites and manganocalcites alter f first into manganite, followed by chlorite into todorokite then by spessartites which weather into birnessite; the Al content of the parent garnet is leached out of the zone. Higher in the profile, garnets alter directly into lithiophorite; in this geochemical environment Al is no longer mobile. In such a layer, early-formed birnessite and manganite are transformed into nsutite along with minor cryptomelane. These later minerals can locally evolve into ramsdellite or pyrolusite. The associated nsutite and lithiophorite are the principal phases of the hard manganese crust capping the hill-rocks of the lateritic landscape of the Ziemougoula area. |
| Databáze: | OpenAIRE |
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