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Registro geológico y geoquímico de impactos de meteoritos terrestres de hace 3400 millones de años
Science (New York, N.Y.)
|September 1, 1989
Resumen
Las antiguas esférulas encontradas en Sudáfrica proporcionan evidencia de grandes impactos de meteoritos en la Tierra primitiva. Estas formaciones geológicas, ricas en elementos del grupo del platino, sugieren orígenes extraterrestres para los eventos geológicos de Archean.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Paleontología Paleontología.
- Ciencias planetarias Ciencias planetarias.
Sus antecedentes:
- El grupo de árboles de higuera en el cinturón de Barberton Greenstone de Sudáfrica contiene antiguas capas de esferulas.
- Estas esférulas se encuentran en varios entornos de deposición de aguas poco profundas a profundas.
Objetivo del estudio:
- Para investigar el origen y la composición de las esferulas del tamaño de arena en el grupo de los árboles de higuera.
- Para determinar si estas esferulas son productos de la actividad volcánica o de impactos de meteoritos.
Principales métodos:
- Análisis geoquímico de la composición de las esferulas, centrado en la abundancia de elementos inmóviles.
- Comparación de la composición de las esferulas con modelos que incluyen basalto, komatiita y condritas carbonáceas.
- Evaluación del contexto geológico, incluyendo la extensión regional y la ausencia de escombros volcánicos.
Principales resultados:
- Las capas esféricas están muy extendidas y son composicionalmente complejas, carecen de escombros volcánicos, lo que sugiere un origen no volcánico.
- Las esférulas están significativamente enriquecidas en iridio y otros elementos del grupo del platino en proporciones condríticas.
- El modelado geoquímico indica que la composición de las esferas es una mezcla de basalto, komatiita y condrita carbonácea CI.
Conclusiones:
- Las esféricas se interpretan como el producto de gotas de silicato líquido apagado de grandes impactos de meteoritos.
- Estos hallazgos proporcionan evidencia de eventos significativos de impacto de meteoritos en la Tierra Arca.
- El estudio refina nuestra comprensión de las interacciones geológicas y extraterrestres de la Tierra primitiva.
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