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Compresibilidades comparativas de las espinillas de silicato: Comportamiento anómalo de (Mg,Fe) 2SiO4
Science (New York, N.Y.)
|January 8, 1993
Resumen
La compresibilidad de los espineles de silicato revela un comportamiento químico distinto entre el hierro y el magnesio a altas presiones. Este hallazgo impacta la comprensión de la composición del interior profundo de la Tierra y la física de los minerales.
Área de la Ciencia:
- Física mineral Física de los minerales
- La geoquímica es la geoquímica.
- Ciencias de la Alta Presión Ciencias de la Alta Presión
Sus antecedentes:
- Los espineles de silicato son minerales clave en el manto de la Tierra.
- Comprender su compresibilidad es crucial para interpretar los datos sísmicos y la composición del manto.
- Estudios anteriores no han caracterizado completamente la compresibilidad de las espinillas ferromagnesianas.
Objetivo del estudio:
- Para determinar las compresividades de cinco espineles de silicato, incluidos los miembros finales y las composiciones ferromagnésicas.
- Para investigar el efecto del contenido de hierro en la compresibilidad de la espinela.
- Para evaluar las características químicas distintivas del hierro y el magnesio a altas presiones.
Principales métodos:
- Análisis cristalográfico de cinco espineles de silicato (gamma-Mg{2}SiO{4}), gamma-Fe{2}SiO{4}), Ni{2}SiO{4} y dos composiciones de ferromagnesio).
- Simultáneos experimentos de alta presión en todos los cristales.
- Medición del módulo de volumen y la compresibilidad.
Principales resultados:
- Se observó un aumento anómalo del 13% en el módulo de volumen con el aumento del contenido de hierro en espinelas de silicato ferromagnesiano.
- La compresibilidad varió significativamente con la composición, destacando las diferencias de composición.
- El Mg(2)SiO(4) tenía un módulo de masa de 184 GPa, mientras que el Fe(2)SiO(4) alcanzaba 207 GPa.
Conclusiones:
- El hierro ferroso y el magnesio exhiben un comportamiento químico más distinto a altas presiones del manto de lo que se suponía anteriormente.
- Esta distinción influye en la interpretación de las composiciones minerales en la zona de transición de la Tierra y el manto inferior.
- Los hallazgos requieren una reevaluación de los modelos para la mineralogía y la dinámica de la Tierra profunda.
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