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Implicaciones para el flujo plástico en el manto profundo del modelado de las dislocaciones en minerales MgSiO3
Philippe Carrez1, Denise Ferré, Patrick Cordier
1Laboratoire de Structure et Propriétés de l'Etat Solide, UMR 8008 CNRS/Université de Lille 1, 59655 Villeneuve d'Ascq Cedex, France.
Nature
|March 3, 2007
Resumen
La convección del manto impulsa la dinámica interior de la Tierra. Nuevos modelos revelan cómo las dislocaciones en las fases de perovskita y postperovskita de MgSiO3 influyen en la deformación plástica y la anisotropía sísmica en el manto profundo.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- La convección del manto, impulsada por el transporte de calor, gobierna la dinámica interior de la Tierra.
- El flujo de alta temperatura de la perovskita MgSiO3 domina el flujo profundo del manto.
- Las propiedades mecánicas de la perovskita MgSiO3 y su fase posterior a la perovskita son cruciales para comprender el manto más bajo, pero siguen siendo en gran medida desconocidas.
Objetivo del estudio:
- Investigar las propiedades mecánicas de las fases de perovskita y postperovskita de MgSiO3 bajo alta presión.
- Comprender el papel de las dislocaciones en la deformación plástica de estos minerales.
- Explorar las implicaciones para la anisotropía sísmica en el manto más bajo de la Tierra.
Principales métodos:
- Desarrollo de modelos básicos de dislocación basados en el marco Peierls-Nabarro.
- Modelado de MgSiO3 perovskita a 100 GPa y después de la perovskita a 120 GPa.
- Análisis de la deformación plástica influenciada por las distorsiones de la célula unitaria y la disociación del núcleo de dislocación.
Principales resultados:
- La deformación plástica en la perovskita se ve afectada significativamente por las distorsiones de las células unitarias ortorrómbicas.
- En la postperovskita de silicato, las dislocaciones se relajan a través de la disociación del núcleo.
- Estos hallazgos proporcionan información sobre el comportamiento mecánico de los minerales en las profundidades de la Tierra.
Conclusiones:
- El estudio proporciona un nuevo enfoque para modelar el comportamiento de dislocación en los minerales del manto de alta presión.
- Los modelos propuestos ofrecen explicaciones para la anisotropía sísmica observada en el manto más bajo.
- Comprender estas dinámicas de dislocación es esencial para modelos geodinámicos precisos del interior de la Tierra.
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