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Episodios tempranos de formación de núcleos de alta presión preservados en el manto de la pluma
Colin R M Jackson1,2, Neil R Bennett1, Zhixue Du1
1Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015, USA.
Nature
|January 26, 2018
Resumen
La Tierra temprana
Área de la Ciencia:
- Geoquímica
- Cosmoquímica
- Ciencias planetarias
Sus antecedentes:
- Las anomalías isotópicas de xenón (Xe) y tungsteno (W) en las rocas del manto proporcionan información sobre la formación de la Tierra.
- Las teorías anteriores vinculaban las anomalías Xe a la desgasificación, pero no podían explicar las anomalías W que ocurrían simultáneamente o su preservación.
Objetivo del estudio:
- Investigar el papel de la partición del yodo (I) y el plutonio (Pu) durante la formación del núcleo en la creación de anomalías isotópicas Xe.
- Para explicar la preservación a largo plazo de estas anomalías en el manto.
Principales métodos:
- Mediciones experimentales de la separación del yodo entre aleaciones líquidas de hierro y silicatos líquidos a alta presión y temperatura.
- Modelado de los primeros procesos de formación del núcleo de la Tierra.
Principales resultados:
- El yodo se vuelve más siderófilo (parecido al hierro) con el aumento de la presión.
- Los episodios de formación de núcleos a alta presión conducen a agotamientos significativos de I/Pu en el manto, independientemente de la volatilidad.
- Estas partes agotadas del manto son más densas, lo que ayuda a su preservación y explica su presencia en los depósitos profundos del manto.
Conclusiones:
- La formación temprana de núcleos a alta presión, no solo la desgasificación, es responsable de las anomalías isotópicas Xe y W en los basaltos derivados de la pluma.
- Estos hallazgos vinculan la diferenciación planetaria temprana con las firmas geoquímicas observables en la Tierra moderna.
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