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La evidencia isotópica de Re-Os para la heterogeneidad de larga duración y los procesos de equilibrio en el manto
Anders Meibom1, Norman H Sleep, C Page Chamberlain
1Geological and Environmental Sciences, 320 Lomita Mall, Stanford University, California 94305, USA. meibom@pangea.stanford.edu
Nature
|October 18, 2002
Resumen
El manto superior de la Tierra es altamente heterogéneo debido a miles de millones de años de extracción de fundición y reciclaje de la corteza. Los datos de los isótopos de renio-osmio (Re-Os) revelan una
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La geoquímica de los isótopos es la geoquímica de los isótopos.
- Petrología Petrología.
Sus antecedentes:
- La composición del manto superior de la Tierra refleja miles de millones de años de procesos geológicos.
- El sistema de isótopos de renio-osmio (Re-Os) es sensible a la extracción de la fusión y al reciclaje de la corteza.
Objetivo del estudio:
- Investigar la heterogeneidad geoquímica del manto superior.
- Extracción de trazas de fundición y reciclaje de material de la corteza terrestre utilizando isótopos Re-Os.
Principales métodos:
- Analizó las composiciones de isótopos de osmio de más de 700 aleaciones de elementos del grupo del platino ricas en osmio.
- Utilizó la sistemática de isótopos Re-Os para evaluar la evolución del manto.
Principales resultados:
- Los datos de isótopos de osmio muestran una amplia distribución gaussiana, lo que indica una extrema heterogeneidad del manto superior.
- Los dominios del manto empobrecidos y enriquecidos pueden permanecer desequilibrados durante miles de millones de años.
Conclusiones:
- Los altos grados de fusión parcial, como los de las crestas oceánicas medias, son necesarios para un equilibrio efectivo de Re-Os.
- La distribución del isótopo de osmio gaussiano sugiere un proceso de mezcla del manto de "puding de ciruela" en lugar de eventos discretos de agotamiento del derretimiento.
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