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Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
Published on: August 31, 2017
La sistemática de isótopos Pt-Re-Os enriquecidos en las lavas de pluma explicada por los sulfuros metasomáticos
Ambre Luguet1, D Graham Pearson, Geoff M Nowell
1Northern Centre for Isotopic and Elemental Tracing, Department of Earth Sciences, University of Durham, South Road, Durham DH1 3LE, UK. ambre.luguet@durham.ac.uk
Science (New York, N.Y.)
|January 26, 2008
Resumen
Las elevadas firmas isotópicas de osmio en los basaltos oceánicos pueden explicarse por procesos del manto, no por intercambio núcleo-manto. Los sulfuros metasomáticos en la fuente del manto proporcionan un mecanismo viable para estas distintas firmas de isótopos de osmio.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología de Isótopos Geología de Isótopos.
- Petrología Petrología.
Sus antecedentes:
- Los basaltos oceánicos exhiben elevadas firmas de isótopos de osmio (186Os-187Os), anteriormente atribuidas al intercambio núcleo-manto.
- La hipótesis de intercambio núcleo-manto presenta desafíos con las limitaciones de la historia térmica y dinámica de la Tierra.
- Comprender el origen de estas firmas isotópicas es crucial para descifrar la evolución del manto y los procesos profundos de la Tierra.
Objetivo del estudio:
- Investigar mecanismos alternativos para las elevadas firmas de 186Os-187Os en los basaltos oceánicos.
- Probar la necesidad del intercambio núcleo-manto para explicar las variaciones isotópicas de osmio observadas.
- Para identificar componentes específicos del manto responsables de generar diversas firmas de isótopos de osmio en las fuentes de basalto.
Principales métodos:
- Análisis de elementos altamente siderófilos en piroxenitas y eclogitas, incluidos sus sulfuros asociados.
- Medición de las proporciones de isótopos de osmio (186Os/188Os) en piroxenitas y aleaciones ricas en platino.
- Modelado geoquímico para evaluar la contribución de diferentes materiales del manto a las firmas de isótopos de osmio basáltico.
Principales resultados:
- La participación de piroxenita a granel en la fuente del manto puede explicar las firmas observadas de 186Os-187Os.
- Los sulfuros metasomáticos, derivados de piroxenita o peridotita fundidos, son una explicación más probable para las firmas isotópicas.
- Estos materiales derivados del manto replican efectivamente las características del isótopo de osmio de los basaltos oceánicos.
Conclusiones:
- El intercambio de núcleo y manto no es necesario para explicar las elevadas firmas de 186Os-187Os en los basaltos oceánicos.
- Los sulfuros metasomáticos dentro del manto proporcionan un mecanismo robusto para generar una diversidad significativa de isótopos de osmio.
- Este hallazgo ofrece una nueva perspectiva sobre la heterogeneidad del manto y los procesos que dan forma a la geoquímica del basalto.
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