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Fósiles mississippianos de rocas metamórficas del sur de los Apalaches y sus implicaciones para la evolución
Science (New York, N.Y.)
|October 29, 1993
Resumen
Los fósiles de Mississippian descubiertos en el cinturón de pizarra Talladega de Alabama indican que el metamorfismo ocurrió más tarde de lo que se pensaba. Este hallazgo requiere una reevaluación de la historia tectónica de los Apalaches del sur.
Área de la Ciencia:
- Paleontología y estratigrafía.
- Geología Estructural y Tectónica.
Sus antecedentes:
- Anteriormente se creía que el cinturón de pizarra de Talladega en Alabama, parte del cinturón occidental de Blue Ridge, había sufrido metamorfismo y deformación durante la orogenia acadiana.
- Las interpretaciones existentes sugerían que estos eventos geológicos ocurrieron antes del período Carbonífero Temprano.
Objetivo del estudio:
- Para establecer una edad más precisa para el metamorfismo y la deformación dentro del cinturón de pizarra de Talladega.
- Reevaluar la historia tectónica de las montañas más meridionales de los Apalaches basándose en nuevas evidencias fósiles.
Principales métodos:
- Recuperación e identificación de fósiles, específicamente Periastron reticulatum, de la pizarra de Erin.
- Análisis estratigráfico para determinar la edad geológica de las capas de roca que contienen fósiles.
Principales resultados:
- Fósiles de Periastron reticulatum Unger en su versión enmendada. Beck fueron recuperados, estableciendo una edad Mississippian (Kinderhookian-Tournaisian) para la pizarra de Erin.
- Esta edad indica que el metamorfismo y la deformación en el cinturón de pizarra de Talladega ocurrieron después del Carbonífero Temprano (Alleghaniano).
Conclusiones:
- Los nuevos datos fósiles contradicen las interpretaciones anteriores del momento de la orogenia acadiana en esta región.
- Se requiere una comprensión revisada de la evolución tectónica de los Montes Apalaches más meridionales, teniendo en cuenta los eventos metamórficos y deformacionales posteriores al Carbonífero Temprano.
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