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Elasticidad de (Mg,Fe) O a través de la transición de espín del hierro en el manto inferior
J C Crowhurst1, J M Brown, A F Goncharov
1Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA. crowhurst1@llnl.gov
Science (New York, N.Y.)
|January 26, 2008
Resumen
El hierro de hierro de hierro.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Ciencias de la Alta Presión Ciencias de la Alta Presión
Sus antecedentes:
- La configuración electrónica del hierro cambia a altas presiones.
- Estos cambios afectan la velocidad sísmica en el manto inferior de la Tierra.
- La ferropericlasa y la perovskita de silicato son minerales huéspedes clave.
Objetivo del estudio:
- Medir el tensor elástico de ferropericlase a través de la transición de espín del hierro.
- Investigar la influencia de las transiciones de espín del hierro en las propiedades sísmicas.
- Correlación de la elasticidad mineral con la estructura de la velocidad sísmica.
Principales métodos:
- Experimentos de alta presión para medir el tensor elástico.
- Experimentos de compresión en ferropericlase ((Mg(1-x),Fe(x)) O) con x = 0,06.
- Análisis del ablandamiento de los módulos elásticos en un rango de presión de 40-60 gigapascales.
Principales resultados:
- Los módulos elásticos se ablandaron hasta un 25% durante la transición de espín de hierro.
- La magnitud del ablandamiento aumenta con el contenido de hierro (hasta x = 0,20).
- Los resultados se alinean con las descripciones termodinámicas de la transición de espín.
Conclusiones:
- La transición de espín del hierro en (Mg,Fe) O es demasiado amplia para discontinuidades sísmicas abruptas.
- Se predice una anomalía negativa correlacionada en las velocidades de compresión y corte.
- Esta anomalía abarca la mayor parte del manto inferior de la Tierra.
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