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Las estrías crípticas en el manto superior reveladas por los isótopos de hafnio en los basaltos de la cordillera
D W Graham1, J Blichert-Toft, C J Russo
1College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA. dgraham@coas.oregonstate.edu
Nature
|March 10, 2006
Resumen
Existen antiguas rayas de composición en el manto superior de la Tierra, reveladas por una distribución isotópica bimodal de hafnio en los basaltos de las cordilleras del sureste de la India. Estas rayas del manto tienen aproximadamente 40 km de espesor.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La geofísica es la geofísica.
- Dinámica del manto dinámica del manto
Sus antecedentes:
- El manto de la Tierra exhibe heterogeneidad isotópica en varias escalas.
- La convección del manto y la tectónica de placas influyen en esta heterogeneidad.
- Comprender la composición del manto es clave para descifrar la evolución de la Tierra.
Objetivo del estudio:
- Para investigar la composición isotópica del manto superior del Océano Índico.
- Para identificar el origen y la distribución de la heterogeneidad del manto.
- Para analizar las implicaciones de la heterogeneidad observada para la dinámica del manto.
Principales métodos:
- Análisis de basaltos de la cresta oceánica media (MORB) de la cresta del sureste de la India (SEIR).
- Medición de las distribuciones isotópicas de hafnio (Hf) en muestras de basalto.
- Análisis estadístico de los datos isotópicos para determinar las características de las rachas.
Principales resultados:
- Se observó una distribución isotópica bimodal del hafnio en los basaltos SEIR.
- Esta bimodalidad indica la presencia de antiguas rayas de composición en el manto superior.
- La densidad numérica de las rayas sigue una distribución de Poisson, con un espesor promedio de ~40 km.
Conclusiones:
- La distribución de rayas observada apoya los modelos de un manto superior bien agitado.
- El reciclaje tectónico de placas y el flujo viscoso son procesos clave que mantienen la heterogeneidad del manto.
- Las estructuras compositivas antiguas persisten a pesar de la convección del manto.
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