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Article dans une revue
Unusual phosphate concretions related to groundwater flow in a continental environment.
Abstract : Occurrence of phosphate cemented-sandstone concretions in alluvial sand containing archaeological layers implies that they have formed during the last 2000 years. Morphology and petrography of the concretions indicates a relationship with groundwater cementation. The phosphate cement of the concretions consists of concentric isopachous aureoles, about 10 mm thick, that wrap the detrital grains. Aureoles are formed of collophane, the cryptocrystalline or amorphous variety of hydroxyapatite. Geochemical modeling indicates that the apatite cement likely results from the leaching of a preexisting phosphate deposit (bones?) in an acidic soil environment and the precipitation of dissolved phosphate under pH control at the mixing zone of down-moving soil-water with the calcite-saturated groundwater.
https://hal-mines-paristech.archives-ouvertes.fr/hal-00646828
Contributeur : Médard Thiry <>
Soumis le : mercredi 30 novembre 2011 - 17:59:04
Dernière modification le : mercredi 14 octobre 2020 - 04:13:23
Contributeur : Médard Thiry <>
Soumis le : mercredi 30 novembre 2011 - 17:59:04
Dernière modification le : mercredi 14 octobre 2020 - 04:13:23