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Estructuras termoquímicas bajo África y el Océano Pacífico
Allen K McNamara1, Shijie Zhong
1Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA. allen.mcnamara@asu.edu
Nature
|October 21, 2005
Resumen
La historia de subducción de la Tierra da forma a las estructuras del manto profundo. Los modelos numéricos muestran que los movimientos pasados de las placas crean densos montones termoquímicos debajo de África y el Pacífico, coincidiendo con las observaciones sísmicas.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología.
- Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- Existen grandes anomalías sísmicas de baja velocidad en el manto inferior debajo de África y el Pacífico.
- Estas anomalías no se explican completamente solo por las variaciones de temperatura.
- Los modelos anteriores sugerían pilas termoquímicas densas, pero carecían de validación geométrica.
Objetivo del estudio:
- Para investigar si la historia de subducción de la Tierra puede generar estructuras termoquímicas del manto inferior que coincidan con las observaciones sísmicas.
- Para conciliar inferencias sismológicas con modelos de convección del manto.
Principales métodos:
- Modelado numérico de la convección termoquímica.
- Utilizó una geometría esférica tridimensional.
- Velocidades de las placas incorporadas de los últimos 119 millones de años.
Principales resultados:
- La historia de subducción genera con éxito estructuras termoquímicas similares en forma a las anomalías sísmicas observadas.
- El material denso se concentra en un montón de forma de cresta debajo de África.
- Una pila más redondeada de material denso se forma bajo el Océano Pacífico.
Conclusiones:
- La historia de subducción de la Tierra es un factor clave en la formación de estructuras de manto inferior a gran escala.
- Los modelos se alinean con los datos sismológicos, explicando las distintas morfologías de las anomalías de África y el Pacífico.
- Esto proporciona un mecanismo para la formación de pilas termoquímicas del manto profundo.
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