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Evidencia isotópica de la partición del Cr en el núcleo de la Tierra
Frederic Moynier1, Qing-Zhu Yin, Edwin Schauble
1Department of Geology, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA. moynier@levee.wustl.edu
Science (New York, N.Y.)
|February 26, 2011
Resumen
El agotamiento del cromo (Cr) en el manto de silicato de la Tierra fue el resultado de la partición en el núcleo, evidenciado por el enriquecimiento de isótopos ligeros. Esta firma isotópica se formó en lo profundo de un océano de magma durante la acreción planetaria temprana y la oxidación.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Ciencias planetarias Ciencias planetarias.
- La geoquímica de los isótopos es la geoquímica de los isótopos.
Sus antecedentes:
- Los meteoritos primitivos (condritas) son la clave para comprender la formación de los planetas terrestres.
- Se debate el agotamiento de elementos como el cromo (Cr) en el manto de silicatos de la Tierra, con la volatilidad y la partición del núcleo como hipótesis principales.
Objetivo del estudio:
- Para investigar la causa del agotamiento del cromo en la Tierra de silicato a granel.
- Para determinar si la volatilidad o la partición del núcleo explica la distribución elemental e isotópica del cromo.
Principales métodos:
- Mediciones de alta precisión de los isótopos estables de cromo (Cr) en varios meteoritos.
- Comparación de las composiciones isotópicas de los meteoritos con la Tierra de silicato a granel.
- Cálculos teóricos desde el principio. cálculos teóricos.
Principales resultados:
- Los isótopos de meteorito Cr se desvían de los valores terrestres de silicato a granel hasta en ~0.4 por mil.
- El agotamiento de Cr en la Tierra de silicato se atribuye a la partición en el núcleo.
- Se identificó un enriquecimiento preferencial de isótopos ligeros de Cr en el núcleo.
Conclusiones:
- El agotamiento del cromo (Cr) en la porción de silicato de la Tierra se debe a su partición preferencial en el núcleo.
- La firma isotópica observada sugiere que la formación del núcleo ocurrió en las profundidades del manto medio dentro de un océano de magma.
- La acreción de la Tierra y el aumento de la oxidación jugaron un papel en el establecimiento de la composición isotópica de Cr.
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