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Los cristales de olivina se alinean durante el flujo de difusión del manto superior de la Tierra
Tomonori Miyazaki1, Kenta Sueyoshi, Takehiko Hiraga
1Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Nature
|October 18, 2013
Resumen
El flujo de difusión, no solo el flujo de dislocación, puede crear la alineación de los cristales de olivina. Este hallazgo impacta nuestra comprensión del flujo del manto y la anisotropía sísmica en el manto superior de la Tierra.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- La tectónica es la tectónica.
Sus antecedentes:
- La orientación preferida cristalográfica (CPO) en el olivino es crucial para comprender la anisotropía y el flujo del manto superior de la Tierra.
- El deslizamiento por dislocación es el mecanismo tradicionalmente aceptado para generar olivina CPO.
Objetivo del estudio:
- Investigar si el flujo de difusión también puede producir CPO en olivina.
- Para determinar la influencia de la temperatura y la fusión en el desarrollo de CPO durante el creep de difusión.
Principales métodos:
- Deformación experimental de olivino sin hierro (forsterita) bajo diferentes temperaturas y condiciones de fusión.
- Análisis de los patrones de orientación preferida cristalográfica (CPO) resultantes.
Principales resultados:
- El flujo de difusión genera CPO en forsterita, con patrones dependientes de la temperatura y la presencia de fusión.
- La intensidad de la CPO se correlaciona con la temperatura y la fusión, lo que influye en las características de los límites de los granos y el deslizamiento.
- Los patrones de anisotropía sísmica predichos se alinean con la anisotropía radial observada y las variaciones de velocidad sísmica en el manto superior.
Conclusiones:
- El flujo de difusión es un mecanismo significativo para generar olivina CPO y la anisotropía del manto.
- El modelo de arrastre de difusión propuesto explica las observaciones sísmicas a través de diferentes regímenes de temperatura del manto.
- Esto desafía la dependencia exclusiva del flujo de dislocación para interpretar el flujo del manto de la anisotropía sísmica.
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