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RETRACTADO: Una vida media más corta de 146Sm medida y las implicaciones para la cronología de 146Sm-142Nd en el
N Kinoshita1, M Paul, Y Kashiv
1Research Facility Center for Science and Technology, University of Tsukuba, Tsukuba, Japan.
Science (New York, N.Y.)
|March 31, 2012
Resumen
La vida media del samario-146 (146Sm), un isótopo clave para la datación de los primeros eventos del sistema solar, se ha revisado a 68 millones de años. Este hallazgo sugiere líneas de tiempo de diferenciación planetaria más tempranas y más cortas.
Área de la Ciencia:
- * Astrofísica y geoquímica nuclear.
- * Datación radiométrica y cosmoquímica.
- * Geología isotópica y ciencias planetarias.
Sus antecedentes:
- * El extinto radionucleido samario-146 (146Sm) es crucial para la datación de los primeros materiales del sistema solar a través de su producto hijo, el neodimio-142 (142Nd).
- * La vida media exacta y la abundancia inicial de 146Sm son esenciales para interpretaciones cronológicas precisas.
- * Las estimaciones anteriores de la semivida y la abundancia inicial de 146Sm han llevado a incertidumbres en las primeras cronologías del sistema solar.
Objetivo del estudio:
- * Para refinar la vida media del samario-146 (146Sm) utilizando mediciones de la actividad alfa y la proporción atómica.
- * Para recalcular la abundancia inicial de 146Sm en el sistema solar temprano.
- * Reevaluar el tiempo de los eventos de diferenciación del manto planetario utilizando los datos revisados de 146Sm.
Principales métodos:
- * Análisis de las relaciones de actividad alfa del samario-146 (146Sm) con el samario-147 (147Sm).
- * Determinación de las relaciones atómicas entre el samario-146 (146Sm) y el samario-144 (144Sm).
- * Aplicación del sistema isotópico 146Sm142Nd para fechar muestras terrestres, lunares y marcianas.
Principales resultados:
- * Se determinó que la vida media del samario-146 (146Sm) es de 68 ± 7 millones de años, significativamente más corta que el valor aceptado anteriormente.
- * La abundancia inicial de 146Sm en el sistema solar temprano, (146Sm/144Sm) ((0), se estima en 0,0094 ± 0,0005.5.
- * La datación de los eventos de diferenciación del manto de silicato planetario utilizando 146Sm142Nd indica períodos de tiempo más tempranos y más cortos.
Conclusiones:
- * La semivida revisada y la abundancia inicial de samario-146 (146Sm) requieren ajustes a las cronologías tempranas del sistema solar.
- * Los procesos de diferenciación planetaria ocurrieron en una escala de tiempo comprimida y más temprana de lo que se pensaba anteriormente.
- * Este estudio proporciona un cronómetro isotópico más preciso para comprender la evolución inicial de los planetas terrestres y el sistema solar.
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