Argilominerais da porção basal da formação Corumbataí (Bacia do Paraná) na região de Rio Claro/SP
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Data
2008-03-28
Autores
Ibrahim, Liliane [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As rochas sedimentares da Formação Corumbataí (Neopermiano) afloram próximas à borda leste da Bacia do Paraná e na região de Rio Claro (SP) constituem importante fonte de matéria-prima para a indústria cerâmica regional. O objetivo deste trabalho foi estudar a gênese e a evolução dos argilominerais presentes nos litotipos de dois perfis posicionados estratigraficamente na porção basal da Formação Corumbataí. As amostras foram coletadas nas frentes de lavra das minerações Pieroni e Estrela Dalva, localizadas no Distrito de Assistência, município de Rio Claro (SP) e analisadas através de difração de raios X, espectrometria de fluorescência de raios X, microscopia ótica e granulometria por absorção de raios X. A aplicação de técnicas complementares na interpretação dos difratogramas, como decomposição de picos e elaboração de difratogramas calculados, permititu a identificação dos argilominerais individualizados e interestratificados e associá-los aos processos deposicional, diagenético, hidrotermal e intempérico que atuaram ao longo da evolução geológica da Bacia do Paraná. A assembléia dos argilominerais é constituída por illita 2M1, illita 1Md, clorita, illita/clorita, clorita/esmectita e esmectita. O politipo illita 2M1 dioctaédrico é predominante e constitui o único argilomineral detrítico. Os argilominerais illita 1Md, clorita e illita/clorita resultam de transformações provocadas pela atuação de fluidos termais originados a partir da intrusão dos magmas básicos na forma de diques e sills correlatos à Formação Serra Geral, de idade Eocretácea. O interestratificado clorita/esmectita constitui o registro do início da fase pós-hidrotermal.
Corumbataí Formation (Neopermian) sedimentary rocks arise near of the East edge of Parana Basin and in Rio Claro region (SP) constitute important raw material source for the regional ceramic industry. The aim of this work is to show genesis and evolution of clay minerals of the litotypes of two minings stratigraphycally located in Corumbatai Formation basal zone. The samples were collected from Pieroni and Estrela Dalva minings, in Assistencia District, Rio Claro city (SP) and analysed by techniques of X-ray diffraction, chemical analysis, optical microscopy and grain-size distribution. Aplicattion of complementary techniques in difratograms analysis as peak decomposition and calculated patterns difratograms allowed individualized and interstratified clay minerals identification and associate them with deposicional, diagenetic, hidrothermal and weathering processes during Parana Basin geological evolution. Clay minerals assemblage includes illite 2M1, illite 1Md, chlorite, illite/chlorite, chlorite/smectite and smectite. The polytipe illite 2M1dioctahedral is the predominant detritic clay mineral. Illite 1Md, chorite and illite/chlorite are the result of transformation due to basic magmas intrusions as sills and dykes associated to Serra Geral Formation (Eocretaceous). The presence of smectite at the top litotypes is due to weathering processes, conditioned for Cenozoic sediments that recover Corumbatai Formation rocks. The results suggest that the superimposed hidrothermalism on these pelitic rocks from the eocretaceous intrusions related to Serra Geral Formation constitutes the main geologic process during pelitic rocks evolution, changing the previous features and preparing all the posterior mechanisms, including the weathering alteration.
Corumbataí Formation (Neopermian) sedimentary rocks arise near of the East edge of Parana Basin and in Rio Claro region (SP) constitute important raw material source for the regional ceramic industry. The aim of this work is to show genesis and evolution of clay minerals of the litotypes of two minings stratigraphycally located in Corumbatai Formation basal zone. The samples were collected from Pieroni and Estrela Dalva minings, in Assistencia District, Rio Claro city (SP) and analysed by techniques of X-ray diffraction, chemical analysis, optical microscopy and grain-size distribution. Aplicattion of complementary techniques in difratograms analysis as peak decomposition and calculated patterns difratograms allowed individualized and interstratified clay minerals identification and associate them with deposicional, diagenetic, hidrothermal and weathering processes during Parana Basin geological evolution. Clay minerals assemblage includes illite 2M1, illite 1Md, chlorite, illite/chlorite, chlorite/smectite and smectite. The polytipe illite 2M1dioctahedral is the predominant detritic clay mineral. Illite 1Md, chorite and illite/chlorite are the result of transformation due to basic magmas intrusions as sills and dykes associated to Serra Geral Formation (Eocretaceous). The presence of smectite at the top litotypes is due to weathering processes, conditioned for Cenozoic sediments that recover Corumbatai Formation rocks. The results suggest that the superimposed hidrothermalism on these pelitic rocks from the eocretaceous intrusions related to Serra Geral Formation constitutes the main geologic process during pelitic rocks evolution, changing the previous features and preparing all the posterior mechanisms, including the weathering alteration.
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Palavras-chave
Mineralogia, Rochas sedimentares, Geoquimica, Raios X - Difração, Argilominerais, Hidrotermalismo, Clay minerals, Hidrothermalism, Weathering
Como citar
IBRAHIM, Liliane. Argilominerais da porção basal da formação Corumbataí (Bacia do Paraná) na região de Rio Claro/SP. 2008. 136 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Geociências e Ciências Exatas, 2008.