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Formaciones de hierro con bandas subducidas como fuente de zonas de velocidad ultrabaja en el límite núcleo-manto
David P Dobson1, John P Brodholt
1Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK. d.dobson@ucl.ac.uk
Nature
|March 18, 2005
Resumen
Zonas de velocidad ultrabaja (ULVZ) en la Tierra.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Ciencias de la Tierra Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- Las zonas de velocidad ultrabaja (ULVZ) son regiones distintas en el límite núcleo-manto, caracterizadas por velocidades reducidas de ondas sísmicas y mayor densidad.
- Las hipótesis existentes para los orígenes de ULVZ incluyen estanques de fusión de silicatos, reacciones núcleo-manto y sedimentación del núcleo.
- Estas zonas, de aproximadamente 1-10 km de espesor, exhiben reducciones de la velocidad de la onda de compresión del 10-20% y reducciones de la velocidad de la onda de cizallamiento del 10-30%.
Objetivo del estudio:
- Proponer un nuevo origen para las zonas de velocidad ultrabaja (ULVZ).
- Investigar el potencial de las formaciones de hierro con bandas subducidas como fuente de ULVZs.
- Explicar las características sísmicas y de densidad observadas de las ZVUL.
Principales métodos:
- Formulación de hipótesis geológicas.
- Análisis de la composición y el entorno de deposición de las formaciones de hierro en bandas.
- Modelado de los procesos de subducción y el comportamiento de los materiales en el límite núcleo-manto.
Principales resultados:
- Las formaciones de hierro en bandas, compuestas de óxidos de hierro y sílice, se depositaron en los antiguos océanos.
- Estas formaciones, cuando se subducen, podrían alcanzar el límite núcleo-manto.
- Las propiedades de las formaciones de hierro con bandas de subducción se alinean con las características observadas de ULVZ.
Conclusiones:
- Las formaciones de hierro con bandas de subducción representan un origen plausible para las zonas de velocidad ultrabaja (ULVZ).
- Esta hipótesis explica potencialmente las anomalías sísmicas y de densidad observadas en las ZVUL.
- El mecanismo propuesto vincula los antiguos procesos de la Tierra con las estructuras actuales del manto profundo.
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