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Extinciones del Cretácico: evidencia de incendios forestales y búsqueda de material meteorítico
Science (New York, N.Y.)
|October 11, 1985
Resumen
Una capa de hollín en todo el mundo desde el límite Cretácico-Terciario, probablemente de incendios forestales provocados por un meteorito, amplificó significativamente el enfriamiento y oscurecimiento global, impactando las extinciones. Esta capa de hollín era más extensa que los escenarios de invierno nuclear.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Paleoclimatología Paleoclimatología
- El cráter de impacto es el cráter de impacto.
Sus antecedentes:
- El límite Cretácico-Terciario (K-T) marca un evento de extinción masiva.
- Las teorías anteriores sugieren que el polvo de impacto causó el enfriamiento global y el oscurecimiento.
Objetivo del estudio:
- Para analizar el carbono grafítico en muestras de arcilla límite K-T.
- Para determinar el origen y el impacto de esta capa de carbono en el clima de la Tierra y las extinciones.
Principales métodos:
- Análisis de muestras de arcilla de tres sitios del límite K-T.
- Caracterización del tamaño y abundancia de las partículas de carbono grafítico.
- Búsqueda de gases nobles meteoríticos y espinela.
Principales resultados:
- Identificó una capa de hollín en todo el mundo (0,36-0,58% de carbono grafítico) en los sitios del límite K-T.
- El tamaño de las partículas de hollín (0,1-0,5 micrómetros) sugiere el origen de los incendios forestales, posiblemente inducidos por meteoritos.
- La abundancia global de hollín (0,021 g/cm2) mejoró significativamente el enfriamiento por impacto.
- La eficiencia de la producción de hollín en incendios forestales es ~ 10 veces mayor que los modelos de invierno nuclear.
- No se encontraron componentes meteoríticos en las fracciones de carbono.
Conclusiones:
- El hollín generado por los incendios forestales jugó un papel importante en el cambio climático y las extinciones del límite K-T.
- La capa de hollín sugiere una extensa vegetación o la quema de combustibles fósiles.
- El hollín de los incendios forestales es un agente climático más potente de lo que se suponía anteriormente.
- Es poco probable que los cometas fueran fuentes significativas de materia orgánica prebiótica para la Tierra primitiva.
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