Weathering evolution of the rich-phosphates lateritic mantle in Itacupim Island, Pará, Brazil - mineralogy, micromorphology, and geochemistry

Evolução do Manto de Intemperismo Laterítico Rico em Fosfatos na Ilha de Itacupim (PA) - Mineralogia, Micromorfologia e Geoquímica

dc.contributoren-US
dc.contributorpt-BR
dc.creatorDE TOLEDO, MARIA CRISTINA MOTTA
dc.creatorDE OLIVEIRA, SONIA BARROS
dc.creatorDA COSTA, MARCONDES LIMA
dc.creatorPASSOS, CAMILA
dc.creatorDE ALMEIDA, HENRIQUE DINIZ
dc.date2006-06-29
dc.date.accessioned2018-11-07T21:59:14Z
dc.date.available2018-11-07T21:59:14Z
dc.identifierhttps://seer.ufrgs.br/PesquisasemGeociencias/article/view/19520
dc.identifier10.22456/1807-9806.19520
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/2192294
dc.descriptionThe lateritic mantle overlying ultramafic rocks at Itacupim Island (state of Pará, northern Brazil) comprises 5 horizons. From bottom to top they are: (1) altered rock (hornblende, phlogopite, apatite, magnetite, fissural wavellite, and smaller amounts of smectite or kaolinite), (2) a smectitic saprolite (smectite, wavellite, goethite, and traces of hornblende), a kaolinitic saprolite (kaolinite, wavellite, goethite, and traces of phlogopite), a phosphatic duricrust (crandallite, goethite and hematite), and a ferruginous duricrust (hematite, goethite and crandallite). The mineralogical and chemical composition of the saprolitic and duricrust horizons indicate a discontinuity in the weathering evolution: the P-rich crandallitic duricrusts cannot be derived from the P-poor wavellitic saprolites. Most probably, the duricrusts developed during an earlier stage of the weathering evolution, under a drier climate, when the hypogene phosphates (wavellite and apatite) transformed into crandallite. Under subsequent more humid conditions, the weathering alteration of the parent rock led to the dissolution of the hypogene phosphates, resulting in the P-depleted saprolites.en-US
dc.descriptionThe lateritic mantle overlying ultramafic rocks at Itacupim Island (state of Pará, northern Brazil) comprises 5 horizons. From bottom to top they are: (1) altered rock (hornblende, phlogopite, apatite, magnetite, fissural wavellite, and smaller amounts of smectite or kaolinite), (2) a smectitic saprolite (smectite, wavellite, goethite, and traces of hornblende), a kaolinitic saprolite (kaolinite, wavellite, goethite, and traces of phlogopite), a phosphatic duricrust (crandallite, goethite and hematite), and a ferruginous duricrust (hematite, goethite and crandallite). The mineralogical and chemical composition of the saprolitic and duricrust horizons indicate a discontinuity in the weathering evolution: the P-rich crandallitic duricrusts cannot be derived from the P-poor wavellitic saprolites. Most probably, the duricrusts developed during an earlier stage of the weathering evolution, under a drier climate, when the hypogene phosphates (wavellite and apatite) transformed into crandallite. Under subsequent more humid conditions, the weathering alteration of the parent rock led to the dissolution of the hypogene phosphates, resulting in the P-depleted saprolites.pt-BR
dc.formatapplication/pdf
dc.languagepor
dc.publisherInstituto de Geociências /Universidade Federal do Rio Grande do Sulpt-BR
dc.relationhttps://seer.ufrgs.br/PesquisasemGeociencias/article/view/19520/pdf
dc.sourcePesquisas em Geociências; v. 33, n. 2 (2006): Pesquisas em Geociências; 109 - 122pt-BR
dc.source1807-9806
dc.source1518-2398
dc.subjecten-US
dc.subjectlateritization, ferruginous duricrust, phosphatic duricrust.en-US
dc.subjectpt-BR
dc.subjectpt-BR
dc.subjectGeociênciaspt-BR
dc.titleWeathering evolution of the rich-phosphates lateritic mantle in Itacupim Island, Pará, Brazil - mineralogy, micromorphology, and geochemistryen-US
dc.titleEvolução do Manto de Intemperismo Laterítico Rico em Fosfatos na Ilha de Itacupim (PA) - Mineralogia, Micromorfologia e Geoquímicapt-BR
dc.typeArtículos de revistas
dc.typeArtículos de revistas
dc.coverageIlha de Itacupim;Pará;Brasilpt-BR
dc.coveragept-BR
dc.coveragept-BR


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