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Una corta duración del evento límite Cretácico-Terciario: evidencia de helio-3 extraterrestre
S Mukhopadhyay1, K A Farley, A Montanari
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. sujoy@gps.caltech.edu
Science (New York, N.Y.)
|March 10, 2001
Resumen
El evento de extinción del Cretácico-Terciario (K-T) no fue causado por una lluvia de cometas polvorientos. Los análisis de helio-3 extraterrestre revelan una tasa constante de acreción de polvo, lo que sugiere una deposición rápida de la arcilla límite K-T.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Paleontología Paleontología.
- Ciencias planetarias Ciencias planetarias.
Sus antecedentes:
- El evento de extinción Cretácico-Terciario (K-T) marca una transición significativa en la historia de la Tierra.
- Comprender las causas y el momento de este evento es crucial para reconstruir la vida pasada y la dinámica planetaria.
- Las tasas de acreción de polvo interplanetario se pueden rastrear utilizando helio-3 extraterrestre.
Objetivo del estudio:
- Para investigar la tasa de acreción del polvo interplanetario durante el intervalo límite K-T.
- Para determinar si el bólido asociado con el evento de extinción K-T fue parte de una lluvia de cometas.
- Para refinar la línea de tiempo de deposición de la arcilla límite K-T y evaluar las tasas de rotación de la fauna.
Principales métodos:
- Análisis de carbonatos marinos del intervalo que abarca entre hace 63,9 y 65,4 millones de años.
- Medición de las concentraciones extraterrestres de helio-3 como un proxy para la acreción de polvo interplanetario.
- Aplicación del helio-3 como un proxy de flujo constante para estimar las tasas de sedimentación.
Principales resultados:
- Se detectó un flujo casi constante de helio-3 extraterrestre, lo que indica una tasa de acreción estable del polvo interplanetario.
- El bólido del evento de extinción K-T no se asoció con un aumento de la polvorienta del sistema solar, descartando el origen de una lluvia de cometas.
- La deposición de la arcilla límite K-T ocurrió rápidamente, en aproximadamente (10 +/- 2) x 10 ^ 3 años.
Conclusiones:
- La extinción K-T probablemente no fue causada por una lluvia de cometas debido a la ausencia de una mayor acumulación de polvo.
- La rápida deposición de la arcilla límite K-T impide una pausa prolongada en el límite.
- Se requiere una rotación faunal extremadamente rápida para explicar los datos geológicos y paleontológicos observados en el límite K-T.
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