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Las restricciones de isótopos de oxígeno sobre el origen de las gafas de impacto del límite cretáceo-terciario
Science (New York, N.Y.)
|August 21, 1992
Resumen
Los impactos de asteroides crearon esferas de vidrio en el límite entre el Cretácico y el Terciario. Los análisis de isótopos de oxígeno y de elementos principales revelan que estos vidrios son una mezcla de rocas carbonatadas y silicatadas fundidas, no de origen volcánico o de evaporación.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Análisis de Isótopos Análisis de Isótopos
- El cráter de impacto es el cráter de impacto.
Sus antecedentes:
- El límite entre el Cretácico y el Terciario (K-T) marca un evento significativo de extinción masiva.
- Comprender las firmas geológicas del límite K-T es crucial para reconstruir los cambios ambientales pasados.
Objetivo del estudio:
- Para analizar la composición de las esferas de vidrio encontradas en el límite K-T en Haití.
- Para determinar el origen y los procesos de formación de estas gafas de impacto.
Principales métodos:
- Análisis de isótopos de oxígeno por extracción láser de esferas de vidrio individuales.
- Análisis de los elementos principales de las esferas de vidrio.
- Interpretando las tendencias de mezcla geoquímica.
Principales resultados:
- Las esferas de vidrio exhiben una tendencia de mezcla entre composiciones de alto calcio (isótopo de oxígeno pesado) y alto silicio (isótopo de oxígeno ligero).
- Los datos isotópicos y elementales indican la fusión de rocas fuente heterogéneas.
- Los vidrios son una mezcla de rocas carbonatadas y silicatadas.
Conclusiones:
- La línea de mezcla observada es consistente con un evento de impacto de asteroides o cometas hace aproximadamente 65 millones de años.
- El impacto derritió una mezcla de rocas de carbonato y silicato.
- Los procesos volcánicos o mezclas que involucran evaporaciones ricas en sulfatos están excluidos como fuente de estos vidrios.
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