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Potasio en las inclusiones de clinoproxeno de los diamantes
Science (New York, N.Y.)
|February 8, 1991
Resumen
Los minerales de clinopiroxeno, específicamente el diopside y la omfacita, pueden incorporar altos niveles de potasio (K) en su estructura cristalina, lo que desafía las suposiciones anteriores en mineralogía. Este descubrimiento sugiere que el clinopiroxeno puede ser un huésped clave para el potasio en el manto de la Tierra.
Área de la Ciencia:
- La mineralogía es la Mineralogía.
- La geoquímica es la geoquímica.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- La química tradicional de los cristales de piroxeno postula que el potasio (K) es demasiado grande para incorporarse a la estructura del piroxeno.
- Estudios anteriores no han reconocido al clinopiroxeno como un huésped significativo para K en el manto terrestre.
Objetivo del estudio:
- Investigar la presencia e implicaciones de un alto contenido de potasio en las inclusiones de clinopiroxeno que se encuentran dentro de los diamantes.
- Desafiar y refinar la comprensión establecida de la química de los cristales de piroxeno con respecto a la incorporación de K.
Principales métodos:
- Se empleó microscopía electrónica de transmisión analítica (TEM) para obtener imágenes de la estructura cristalina.
- Se utilizaron análisis de microsondas electrónicas (EMPA) para determinar la composición química, incluido el contenido de K.
- Los datos de difracción de rayos X monocristalino (XRD) proporcionaron información sobre los parámetros de la célula unitaria y la estructura cristalina.
Principales resultados:
- Se confirmaron altos contenidos de potasio (hasta 1,5 wt% K2O) en las inclusiones de diopside y omphacite de diamantes.
- Estos clinopiroxenos portadores de K exhiben un alto grado de perfección cristalina y volúmenes de células unitarias anormalmente grandes.
- Las imágenes TEM revelaron una estructura libre de defectos en regiones ricas en K, apoyando a K en una solución sólida.
Conclusiones:
- El clinopiroxeno, incluidos el diopside y la omfacita, puede acomodar cantidades significativas de K en solución sólida, contrariamente a lo que se creía anteriormente.
- El clinopiroxeno se identifica como un huésped potencialmente significativo para K dentro del manto de la Tierra.
- Los hallazgos sugieren que algunas inclusiones de diamantes y clinopiroxeno pueden haberse formado en un entorno de manto enriquecido con K.
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