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Tasas de calibración de la evolución del Cámbrico temprano.
S A Bowring1, J P Grotzinger, C E Isachsen
1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA.
Science (New York, N.Y.)
|September 3, 1993
Resumen
La explosión cámbrica comenzó hace unos 544 millones de años, con etapas tempranas que duraron millones de años. Nuevos métodos de datación revelan una línea de tiempo comprimida para la diversificación del Cámbrico Temprano y la rotación de la fauna.
Área de la Ciencia:
- Geología Geología Geología.
- Paleontología Paleontología.
- Geocronología Geocronología.
Sus antecedentes:
- El período cámbrico fue testigo de una rápida diversificación de la vida, conocida como la explosión cámbrica.
- La datación precisa de las rocas del Cámbrico es crucial para comprender las tasas evolutivas, pero ha sido un desafío.
- Se necesitan métodos geocronológicos de alta precisión para resolver el momento de los eventos del Cámbrico Temprano.
Objetivo del estudio:
- Datar con precisión el comienzo del período Cámbrico y sus primeras etapas.
- Para cuantificar las tasas evolutivas durante la explosión cámbrica.
- Para refinar la línea de tiempo de la diversificación y el volumen de negocios de la fauna del Cámbrico Temprano.
Principales métodos:
- La geocronología de uranio-plomo-zircón se empleó para fechar las rocas del Cámbrico inferior.
- Se analizaron datos geocronológicos para establecer edades de alta precisión para las etapas del Cámbrico.
- Las técnicas de datación radiométrica proporcionaron restricciones en la duración de las etapas Manykaian, Tommotian y Atdabanian.
Principales resultados:
- El período Cámbrico comenzó hace aproximadamente 544 millones de años.
- La etapa más antigua (Manykaian) del Cámbrico duró al menos 10 millones de años.
- Las etapas tommociana y atdabaniana colectivamente abarcaron solo de 5 a 10 millones de años.
Conclusiones:
- La línea de tiempo del Cámbrico Temprano está comprimida, lo que indica un ritmo rápido de diversificación de la fauna.
- Los sucesivos eventos de rotación del Cámbrico también ocurrieron rápidamente dentro de un marco de tiempo más corto.
- La geocronología precisa es esencial para interpretar con precisión la dinámica evolutiva durante el Cámbrico.
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