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Historia del impacto lunar desde (40) Ar/(39) Ar datación de las esferas de vidrio
1Department of Geology and Geophysics, Department of Physics, University of California, Berkeley, CA 94720, USA. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, U.
Science (New York, N.Y.)
|March 10, 2000
Resumen
El análisis de las esferulas lunares revela que las tasas de cráteres de impacto fluctuaron durante 3.500 millones de años. Los aumentos recientes en los impactos lunares se correlacionan con la Tierra.
Área de la Ciencia:
- Geología lunar y estudios de cráteres de impacto.
- Datación radiométrica y geocronología.
- Ciencia planetaria y evolución del sistema Tierra-Luna.
Sus antecedentes:
- Las esféricas lunares son cuentas de vidrio formadas por impactos de meteoritos en la Luna.
- La técnica isocrónica Argon-Argon (40Ar/39Ar) fecha estos eventos de impacto.
- Comprender la historia del impacto lunar proporciona información sobre la evolución del sistema solar.
Objetivo del estudio:
- Para analizar la distribución por edades de las esférulas lunares del suelo del Apolo 14.
- Para reconstruir la tasa de cráteres lunares en los últimos 3.500 millones de años.
- Investigar correlaciones potenciales entre la historia de los impactos lunares y la evolución biológica de la Tierra.
Principales métodos:
- Aislamiento de 155 esferulas lunares de 1 gramo de regolito del Apolo 14.
- La datación de las esferulas mediante la técnica de isocrón Argon-Argon (40Ar/39Ar).
- Análisis estadístico de las edades de impacto para determinar las variaciones de la tasa de cráteres.
Principales resultados:
- La tasa de cráteres lunares disminuyó de 2 a 3 veces en los últimos 3.500 millones de años.
- Se observó una tasa mínima de cráteres hace 500-600 millones de años.
- La tasa de formación de cráteres aumentó 3,7 ± 1,2 veces en los últimos 400 millones de años.
Conclusiones:
- El flujo de impacto lunar no ha sido constante, mostrando fluctuaciones significativas.
- El reciente aumento en los impactos lunares coincide con un período de rápida radiación evolutiva en la Tierra.
- Se necesita más investigación para establecer la causalidad entre los impactos lunares y los cambios bióticos terrestres.
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