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Determination of Aggregate Surface Morphology at the Interfacial Transition Zone ITZ
Published on: December 16, 2019
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Las firmas de isótopos de helio primordiales y reciclados en la zona de transición del manto
S Timmerman1, M Honda2, A D Burnham2
1Research School of Earth Sciences, Australian National University, 142 Mills Road, Acton, ACT 2601, Australia. suzette.timmerman@anu.edu.au.
Science (New York, N.Y.)
|August 17, 2019
Resumen
Las firmas de isótopos de helio del manto profundo se midieron en diamantes superprofundos. Una fuente de manto profundo de alto contenido de helio-3/helio-4 menos desgasificada se infiltra en la zona de transición, influyendo en las composiciones de basalto.
Área de la Ciencia:
- Geoquímica
- La geofísica
- Petrología
Sus antecedentes:
- Las composiciones de isótopos de basalto revelan las reservas químicas interiores de la Tierra.
- La medición directa de los isótopos de helio en el manto profundo es un desafío.
- Comprender el helio del manto profundo es crucial para interpretar las firmas de basalto en erupción.
Objetivo del estudio:
- Para medir las proporciones de isótopos de helio (He), estroncio (Sr) y plomo (Pb) en inclusiones de fluido de diamante superprofundas.
- Para investigar la firma del isótopo de helio en el manto profundo.
- Para entender el origen de la variabilidad isotópica en los basaltos de las islas oceánicas.
Principales métodos:
- Análisis de las proporciones de isótopos He-Sr-Pb en las inclusiones fluidas de diamantes originarios de la zona de transición (profundidad 410 × 660 km).
- Utilizando diamantes superprofundos como muestras prístinas, no afectadas por la desgasificación y la contaminación de la corteza.
Principales resultados:
- Se observó una variabilidad extrema del isótopo He-C-Pb-Sr.
- Se identificaron altas proporciones de 3He/4He correlacionadas con altas concentraciones de helio.
- Indicó la presencia de una fuente de manto profundo de 3He/4He menos desgasificada.
Conclusiones:
- Una fuente profunda del manto con alto 3He/4He se infiltra en la zona de transición.
- La interacción entre esta fuente profunda y los materiales reciclados en la zona de transición genera diversidad isotópica.
- Este proceso explica las diversas composiciones isotópicas que se encuentran en los basaltos de las islas oceánicas.
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