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La posperovskita rica en hierro y el origen de las zonas de velocidad ultrabaja
Wendy L Mao1, Ho-Kwang Mao, Wolfgang Sturhahn
1Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. wmao@lanl.gov
Science (New York, N.Y.)
|April 29, 2006
Resumen
Las regiones con velocidades sísmicas ultrabajas en el límite núcleo-manto pueden ser causadas por silicatos posperovskitas ricos en hierro. Estos silicatos son estables y se forman a través de reacciones núcleo-manto, acumulándose potencialmente en parches sísmicos observables.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Sismología Sismología Sismología.
Sus antecedentes:
- El límite entre el núcleo y el manto de la Tierra (CMB) exhibe regiones con velocidades sísmicas ultrabajas.
- Estas anomalías indican propiedades materiales inusuales en la base del manto inferior.
Objetivo del estudio:
- Investigar la composición y la estabilidad de los materiales responsables de las velocidades sísmicas ultrabajas en el CMB.
- Para vincular las observaciones experimentales con los datos sismológicos.
Principales métodos:
- Síntesis experimental y caracterización de las fases de silicato post-perovskita.
- Experimentos de alta presión y alta temperatura que simulan las condiciones del CMB.
- Análisis de las velocidades de las ondas sísmicas (compresión y cizallamiento) y la relación de Poisson.
Principales resultados:
- Las fases de silicato postperovskita con hasta 40 mol% de FeSiO3 son estables en condiciones de CMB.
- Estos silicatos ricos en hierro exhiben velocidades de onda de compresión y corte ultrabajas y una alta relación de Poisson.
- La formación de estas fases es posible a través de reacciones núcleo-manto.
Conclusiones:
- Los silicatos posperovskita ricos en hierro son una explicación plausible para las zonas de velocidad ultrabaja (ULVZ) observadas en el CMB.
- La dinámica del manto puede concentrar este material, creando parches detectables sísmicamente.
- Este hallazgo concilia los experimentos de física mineral con las observaciones sismológicas de las profundidades de la Tierra.
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