Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil
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| Formato: | Artículo científico |
| Lenguaje: | en |
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Academia Brasileira de Ciências
2006
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| _version_ | 1876466831010562048 |
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| author | Jackson D.S. Paz |
| author_facet | Jackson D.S. Paz |
| contents | Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil Jackson D.S. Paz Dilce de Fátima Rossetti Multidisciplinaria (Ciencias Naturales y Exactas) sabkha São Luís evaporite paleolake petrography An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposedin the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishingbetween primary and secondary evaporites, and reconstructing their post-depositional evolution. Sevenevaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gypsum or anhydrite; 3.fibrous to acicular gypsum; 4. mosaic gypsum; 5. brecciated gypsum or gypsarenite; 6. pseudo-nodularanhydrite or gypsum; and 7. rosettes of gypsum. The three first phases of gypsum display petrographiccharacteristics that conform to a primary nature. The fibrous to acicular and mosaic gypsum were formedby replacement of primary gypsum, but their origin took place during the eodiagenesis, still under influenceof the depositional setting. These gypsum morphologies are closely related to the laminated evaporites,serving to demonstrate that their formation was related to replacements that did not affect the primarysedimentary structures. The pseudo-nodular anhydrite or gypsum seems to have originated by mobilizationof sulfate-rich fluids during burial, probably related to halokinesis. The rosettes of gypsum, which interceptall the other gypsum varieties, represent the latest phase of evaporite formation in the study area, resultingfrom either intrastratal waters or surface waters during weathering. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778314 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.78 |
| format | Artículo científico |
| id | redalyc_32778314 |
| institution | Redalyc |
| language | en |
| publishDate | 2006 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil Jackson D.S. Paz Multidisciplinaria (Ciencias Naturales y Exactas) sabkha São Luís evaporite paleolake petrography Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil Jackson D.S. Paz Dilce de Fátima Rossetti Multidisciplinaria (Ciencias Naturales y Exactas) sabkha São Luís evaporite paleolake petrography An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposedin the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishingbetween primary and secondary evaporites, and reconstructing their post-depositional evolution. Sevenevaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gypsum or anhydrite; 3.fibrous to acicular gypsum; 4. mosaic gypsum; 5. brecciated gypsum or gypsarenite; 6. pseudo-nodularanhydrite or gypsum; and 7. rosettes of gypsum. The three first phases of gypsum display petrographiccharacteristics that conform to a primary nature. The fibrous to acicular and mosaic gypsum were formedby replacement of primary gypsum, but their origin took place during the eodiagenesis, still under influenceof the depositional setting. These gypsum morphologies are closely related to the laminated evaporites,serving to demonstrate that their formation was related to replacements that did not affect the primarysedimentary structures. The pseudo-nodular anhydrite or gypsum seems to have originated by mobilizationof sulfate-rich fluids during burial, probably related to halokinesis. The rosettes of gypsum, which interceptall the other gypsum varieties, represent the latest phase of evaporite formation in the study area, resultingfrom either intrastratal waters or surface waters during weathering. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778314 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.78 |
| title | Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) sabkha São Luís evaporite paleolake petrography |
| url | https://www.redalyc.org/articulo.oa?id=32778314 |