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Las clastas de mesosiderita con las anomalías de europium positivo más extremas entre las rocas del sistema solar
Science (New York, N.Y.)
|August 21, 1992
Resumen
Los gabros de plagioclase de pigeonita encontrados en mesosideritas exhiben fraccionamientos extremos de elementos de tierras raras (REE), incluidas anomalías significativas de europio. Estos hallazgos sugieren que procesos ígneos complejos y de múltiples etapas ocurrieron en los primeros asteroides del sistema solar.
Área de la Ciencia:
- * Ciencias planetarias Ciencias planetarias
- * La geoquímica.
- * Petrología * Petrología.
Sus antecedentes:
- * Las mesosideritas son meteoritos brecciados de piedra y hierro que contienen clastos de rocas ígneas.
- * Los gabros de plagioclase de pigeonita dentro de las mesosideritas muestran firmas geoquímicas inusuales.
- * Los patrones de fraccionamiento de los elementos de tierras raras (REE) proporcionan información sobre los procesos ígneos y metamórficos.
Objetivo del estudio:
- * Para analizar las fraccionamientos de elementos de tierras raras extremas (REE) en los clastos de gabbro de plagioclase de pigeonita de mesosideritas.
- * Para investigar los patrones REE de merrillite dentro de estos clastos y su relación con el equilibrio de silicato.
- * Para inferir los primeros procesos ígneos y metamórficos en los cuerpos padres de los asteroides.
Principales métodos:
- * Análisis geoquímico de las concentraciones de elementos de tierras raras (REE) en los clastos gabbroicos y la merrillita.
- * Comparación de los patrones observados de REE con las rocas ígneas y metamórficas conocidas de la Tierra, la Luna y otros cuerpos progenitores de meteoritos.
- * Interpretación de los datos REE en el contexto de los primeros procesos del sistema solar.
Principales resultados:
- * Los clastos de Gabbro muestran fraccionamientos extremos de REE con mayores anomalías positivas de europio que las rocas ígneas conocidas anteriormente.
- * Los REE ligeros se agotan significativamente en relación con los REE pesados, superando los agotamientos en gabros acumulados comparables.
- * La merillita dentro de un clast muestra agotamiento de REE ligero y una gran anomalía positiva de europium debido al equilibrio metamórfico.
Conclusiones:
- * Las proporciones extremas de REE en los clastos de mesosiderita indican procesos ígneos en múltiples etapas en los primeros asteroides del sistema solar.
- * El derretimiento a gran escala de la corteza terrestre, potencialmente provocado por impactos o inducción solar, probablemente impulsó estos procesos.
- * Estos hallazgos desafían los modelos existentes de la evolución temprana de los asteroides y la formación de la corteza.
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