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Restricciones sismológicas sobre una posible raíz de penacho en el límite núcleo-manto
Sebastian Rost1, Edward J Garnero, Quentin Williams
1Department of Geological Sciences, Arizona State University, Box 871404, Tempe , Arizona 85287-1404, USA. srost@asu.edu
Nature
|June 3, 2005
Resumen
El análisis de ondas sísmicas revela una bolsa densa y parcialmente fundida en el límite entre el núcleo y el manto de la Tierra, al este de Australia. Esta estructura compleja, a diferencia de la fusión pura, sugiere cristales atrapados y puede indicar una zona profunda de raíces de pluma.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología Sismología.
- Ciencias de la Tierra Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- El límite entre el núcleo y el manto de la Tierra exhibe estructuras complejas, no una simple interfaz.
- Las reducciones de la velocidad de las ondas sísmicas sugieren complejidades localizadas en el manto más bajo.
Objetivo del estudio:
- Para presentar evidencia de un bolsillo de material específico, denso y parcialmente fundido en el límite núcleo-manto.
- Para caracterizar las propiedades sísmicas y las implicaciones de esta anomalía.
Principales métodos:
- Análisis de conjuntos de precursores de ondas sísmicas anómalas (ScP, por sus siglas en inglés).
- Cálculo de las velocidades de compresión y de onda de corte y los cambios de densidad.
Principales resultados:
- Descubrimiento de una bolsa de material denso y parcialmente fundido de 8,5 km de espesor y 50 km de ancho al este de Australia.
- Se observaron reducciones de la velocidad sísmica (8% de compresión, 25% de cizallamiento) y un aumento de la densidad del 10%.
- Los datos sísmicos indican una composición de fusión no pura que requiere un mecanismo de captura de fusión.
Conclusiones:
- La anomalía es probablemente una estructura acumulada formada por la fusión atrapada, posiblemente de una región caliente superpuesta.
- Esta estructura puede representar la zona de raíz de una pluma ascendente del manto.
- Los hallazgos ponen de relieve la intrincada naturaleza del límite núcleo-manto.
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