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Acreción rápida y diferenciación temprana de Marte indicada por 142Nd/144Nd en los meteoritos SNC
C L Harper1, L E Nyquist, B Bansal
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138.
Science (New York, N.Y.)
|January 13, 1995
Resumen
Las anomalías del isótopo de neodimio en el meteorito de Nakhla revelan la diferenciación temprana del manto marciano. Esto sugiere que Marte evitó impactos gigantes dentro de los 27 millones de años del origen del sistema solar.
Área de la Ciencia:
- Ciencias planetarias Ciencias planetarias.
- La geoquímica es la geoquímica.
- Cosmoquímica es la cosmoquímica.
Sus antecedentes:
- Pequeñas variaciones en las proporciones de neodimio-142 a neodimio-144 en los cuerpos planetarios indican una diferenciación temprana.
- Estas variaciones son el resultado de la desintegración del samario-146, un radionúclido extinto.
- Tales anomalías isotópicas proporcionan información sobre las escalas de tiempo de acreción planetaria.
Objetivo del estudio:
- Para investigar la diferenciación planetaria temprana utilizando isótopos de neodimio.
- Para restringir el tiempo de diferenciación temprana y acreción en Marte.
- Para evaluar el historial de impactos de Marte basado en evidencia isotópica.
Principales métodos:
- Análisis de las proporciones de isótopos de neodimio (neodimio-142 al neodimio-144) en el meteorito marciano Nakhla.
- Utilizando la desintegración del samario-146 como un cronómetro para los primeros eventos del sistema solar.
- Comparando las firmas isotópicas en Nakhla con las del neodimio normal.
Principales resultados:
- El meteorito de Nakhla muestra un exceso de 59 +/- 13 ppm en el neodimio-142 al neodimio-144.
- Esta anomalía indica que la diferenciación ocurrió en el manto marciano antes de hace 4.539.000 millones de años.
- Los hallazgos implican que Marte no experimentó impactos gigantes más tarde de 27 millones de años después de la formación del sistema solar.
Conclusiones:
- Las anomalías del isótopo de neodimio en los meteoritos son herramientas poderosas para comprender la evolución planetaria temprana.
- Marte sufrió una diferenciación significativa del manto muy temprano en su historia.
- La historia temprana de Marte, particularmente su registro de impactos, se puede descifrar a través del análisis isotópico de muestras devueltas.
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