Efectos de alteración hidrotermal y meteorización en vulcanitas del Grupo Aguacate, Costa Rica
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| Autor: | |
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| Formato: | artículo original |
| Estado: | Versión publicada |
| Fecha de Publicación: | 2011 |
| Descripción: | The volcanic rocks of the Aguacate Group located at S and SW of the "Cordille-ra de Tilarán" represent an orogenic family principally composed by members of the tholeiític series and a few of the calc-alkaline series (sensu MIYASHIRO 1974). The main volcanic rocks of this Group are: uartz-latiandesite, latiandesite, andesite and tuffite. Three types of wall rock alteration can be found in these rocks: 1. Strong propylitization in direct relation to pyrite fractures and in rocks in which the clay phases chlorite, beidellite, kaolinite and illite have been developed; 2. Intermediate to advanced argillic alteration with the subzones: a) kaolinite, b) kaolinite, aluníte, e) kaolinite, pyrophyllite d) beidellíte, illite/beidellite; e) kaolinite, cristobalite; 3. Incipient sericitic alteration with quartz and pyrite. 25%. Probably alunite is formed by the reaction of sulfuric acid with illite: KA13Si3010(OH)2 + 4H + 2504 KA13(304)2(OH) + 35i02 The theoretical standard free energy of chis reaetion is -42.0 Kcal/mol by The limits between the different types of alterations are not elearly defined. Secondary minerals e.g. chlorite, disordered kaolinite (fire clay) and beide-Ilite are also formed by reasons of weathering in zones which are not affected by hidrothermal alteration. |
| País: | Portal de Revistas UCR |
| Institución: | Universidad de Costa Rica |
| Repositorio: | Portal de Revistas UCR |
| Lenguaje: | Español |
| OAI Identifier: | oai:portal.ucr.ac.cr:article/10466 |
| Acceso en línea: | https://revistas.ucr.ac.cr/index.php/geologica/article/view/10466 |