Análisis petrográfico y estratigráfico de las terrazas marinas de la Formación Tablazo provincia de Santa Elena-Ecuador
Fecha
2019
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Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
La Formación Tablazo se encuentra en discordancia sobre las rocas del cretácico-paleógenas de la Península de Santa Elena. La edad asignada para esta formación es el pleistoceno en un ambiente marino somero. Este estudio tiene como objetivo la descripción petrográfica de la Fm. Tablazo para su ubicar el ambiente sedimentario de la misma. Se utilizo la clasificación de Dunham (1962) para rocas carbonáticas y el método de Bernard (1967) para calcimetría. Se escogieron tres afloramientos para descripción macroscópica de las muestras de mano, su textura y tipo de cementación. Las rocas tienen en promedio 52% de composición de carbonato de calcio y corresponden a grainstones y packstones formadas por fragmentos de organismos (conchas, foraminíferos), para el primer caso el tipo de cemento es carbonático por lo observado en secciones delgadas y para el segundo se identificó en la matriz infiltraciones de microesparita. Los ambientes de alta energía se corresponden para los sitios estudiados.
The Tablazo Formation is in discordance with Cretoceous-Paleogene rocks from the Peninsula de Santa Elena. The age assigned is Pleistocene and a shallow marine depositional environment. This study is focused in the stratigraphic, sedimentary and petrographic description of the Tablazo Formation to detail the sedimentary environment. Three outcrops were chosen to macroscopic petrographic, texture and cementation type description from hand samples. The Dunham classification (1962) and the Bernard method (1967) for carbonate rocks were used, also calcimetry analysis. The rocks have an average of 52% of calcium carbonate composition and correspond to grainstones formed by fragments of organisms (bivalvos and foraminifera shells), and in a smaller proportion, other components were identified such as plagioclase and micas joined with carbonate cement, as observed in the thin sections, this cement corresponds to microesparite. Finally, the sites studied correspond to high-energy environemts.
The Tablazo Formation is in discordance with Cretoceous-Paleogene rocks from the Peninsula de Santa Elena. The age assigned is Pleistocene and a shallow marine depositional environment. This study is focused in the stratigraphic, sedimentary and petrographic description of the Tablazo Formation to detail the sedimentary environment. Three outcrops were chosen to macroscopic petrographic, texture and cementation type description from hand samples. The Dunham classification (1962) and the Bernard method (1967) for carbonate rocks were used, also calcimetry analysis. The rocks have an average of 52% of calcium carbonate composition and correspond to grainstones formed by fragments of organisms (bivalvos and foraminifera shells), and in a smaller proportion, other components were identified such as plagioclase and micas joined with carbonate cement, as observed in the thin sections, this cement corresponds to microesparite. Finally, the sites studied correspond to high-energy environemts.
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Palabras clave
FORMACIÓN TABLAZO, TERRAZAS MARINAS, PLEISTOCENO