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Una dinamo temprana del núcleo lunar impulsada por la convección termoquímica del manto
Dave R Stegman1, A Mark Jellinek, Stephen A Zatman
1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA. dstegman@eps.berkeley.edu
Nature
|January 10, 2003
Resumen
Una dinamo lunar temprana, que genera el campo magnético de la Luna, puede haber sido alimentada por un aumento temporal en el flujo de calor del núcleo. Este aumento se debió a que una capa rica en radiactividad se volcó dentro del manto lunar.
Área de la Ciencia:
- Ciencias lunares La ciencia lunar es la ciencia lunar.
- La geofísica es la geofísica.
- La dinámica planetaria es una dinámica planetaria.
Sus antecedentes:
- Los datos paleomagnéticos y las muestras de Apolo sugieren que la Luna tenía un campo magnético de hace 3.900 a 3.600 millones de años, lo que implica una antigua dínamo lunar.
- Los modelos de evolución térmica existentes no explican el flujo de calor del núcleo suficiente para alimentar una dínamo después de hace 4.200 millones de años.
Objetivo del estudio:
- Para explicar la existencia y el momento de la dinamo lunar temprana.
- Para conciliar la evidencia paleomagnética con los modelos de evolución térmica.
Principales métodos:
- Utilizó un modelo tridimensional de convección esférica.
- Investigó el papel de un manto lunar estratificado con una capa basal enriquecida con radioactividad.
Principales resultados:
- Una densa y radiactiva "cobertura térmica" en la base del manto lunar inició inhibiendo el enfriamiento del núcleo y la acción de la dínamo.
- El calentamiento radiactivo posterior aumentó la flotabilidad de la manta, haciendo que se elevara y se volcara en el manto.
- El evento de volcado aumentó transitoriamente el flujo de calor del núcleo, suficiente para alimentar una dinamo lunar de corta duración.
Conclusiones:
- Un aumento transitorio en el flujo de calor del núcleo, impulsado por el vuelco del manto lunar, puede explicar la dinamo lunar temprana.
- Este evento de volcado también puede explicar la erupción de los basaltos de marea lunar ricos en torio y titanio.
- El mecanismo propuesto concilia las observaciones paleomagnéticas con la historia térmica lunar.
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