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Anisotropía de corte elástico de ferropericlase en el manto inferior de la Tierra
Hauke Marquardt1, Sergio Speziale, Hans J Reichmann
1GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany. hama@gfz-potsdam.de
Science (New York, N.Y.)
|April 11, 2009
Resumen
La ferropericlase mejora significativamente la anisotropía de corte sísmico en el manto inferior, especialmente después del hierro.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Sismología Sismología Sismología.
Sus antecedentes:
- La anisotropía de cizallamiento sísmico en el manto más bajo de la Tierra se atribuye principalmente a la anisotropía de cizallamiento elástico y la orientación preferida de la rejilla de los minerales constituyentes.
- Minerales como la perovskita, la posperovskita y la ferropericlasa son componentes clave que influyen en la propagación de las ondas sísmicas.
Objetivo del estudio:
- Para investigar la anisotropía de corte elástico del monocristal (Mg0.9Fe0.1) O bajo alta presión.
- Para determinar la influencia del contenido de hierro y las transiciones de espín inducidas por la presión en la anisotropía sísmica.
- Para evaluar la contribución de la ferropericlase a la anisotropía sísmica global de corte en el manto inferior.
Principales métodos:
- Mediciones de alta presión de la anisotropía de corte elástico utilizando un solo cristal (Mg0.9Fe0.1) O.
- Análisis de los cambios de anisotropía a través del rango de presión de transición de espín de hierro (40 60 GPa).
Principales resultados:
- La anisotropía de corte elástico de (Mg0.9Fe0.1) O aumentó significativamente a través de la transición de giro inducida por presión del hierro.
- El mayor contenido de hierro amplificó aún más la anisotropía de corte elástico.
- (Mg,Fe) O exhibe una anisotropía de corte elástico al menos un 50% más fuerte en comparación con MgO.
Conclusiones:
- La ferropericlase es el mineral dominante responsable de la anisotropía de corte sísmico en el manto inferior de la Tierra.
- Los hallazgos requieren modelos geodinámicos revisados que tengan en cuenta la anisotropía mejorada de ferropericlase.
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