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Las restricciones del isótopo de renio-osmio en la edad de los meteoritos de hierro
Science (New York, N.Y.)
|February 28, 1992
Resumen
Las edades de los meteoritos de hierro revelan un rápido enfriamiento de sus cuerpos madre, con hierros IIA solidificándose dentro de los 100 millones de años de formación del sistema solar. Otros grupos de meteoritos de hierro muestran historias de enfriamiento posteriores.
Área de la Ciencia:
- Cosmoquímica es la cosmoquímica.
- Ciencias planetarias Ciencias planetarias.
- Geocronología Geocronología.
Sus antecedentes:
- Los meteoritos de hierro proporcionan información crucial sobre los primeros procesos del sistema solar.
- Comprender sus edades de formación y enfriamiento ayuda a limitar las líneas de tiempo de la evolución planetaria.
Objetivo del estudio:
- Para determinar las edades de renio-osmio (Re-Os) y las composiciones isotópicas de osmio de los meteoritos de hierro.
- Establecer cronogramas precisos de formación y enfriamiento para diferentes grupos de meteoritos de hierro.
Principales métodos:
- Se empleó la espectrometría de masas de ionización térmica negativa (NTIMS).
- El análisis se centró en las concentraciones de renio y osmio y las composiciones isotópicas de osmio.
Principales resultados:
- Los meteoritos de hierro IIA dan una edad isocrónica de aproximadamente 4500 millones de años, con una incertidumbre de +/-31 millones de años.
- La edad mínima permitida para los meteoritos de hierro IIA es de 4460 millones de años.
- Otros grupos de meteoritos de hierro se ubican por encima del isocrón IIA, lo que sugiere un enfriamiento posterior.
Conclusiones:
- El cuerpo madre de los hierros magmáticos del IIAB se derritió y se enfrió rápidamente, dentro de los 100 millones de años de la formación de la condrita.
- Los cuerpos planetarios de otros grupos de meteoritos de hierro probablemente experimentaron fases de enfriamiento significativamente posteriores en comparación con los hierros IIA.
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