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Impresiones discoidales y restos de fósiles de más de 1.200 millones de años de antigüedad
Birger Rasmussen1, Stefan Bengtson, Ian R Fletcher
1Centre for Global Metallogeny, Department of Geology and Geophysics, University of Western Australia, Crawley, Western Australia 6009, Australia. brasmussen@geol.uwa.edu.au
Science (New York, N.Y.)
|May 11, 2002
Resumen
Los fósiles en Australia.
Área de la Ciencia:
- Paleontología Paleontología.
- Geocronología Geocronología.
- Geología sedimentaria Geología sedimentaria.
Sus antecedentes:
- La Formación Stirling Range en el suroeste de Australia contiene impresiones discoidales y fósiles parecidos a rastros.
- Estos fósiles fueron previamente atribuidos a la biota Ediacaran (más joven que 600 millones de años).
Objetivo del estudio:
- Para fechar con precisión la Formación de la Cordillera de Stirling utilizando métodos geocronológicos.
- Reevaluar el origen biológico y la edad de las impresiones discoidales y los restos fósiles.
Principales métodos:
- La geocronología U-Th-Pb se realizó en circón detrital y monazita.
- También se analizó monazita metamórfica de bajo grado.
Principales resultados:
- La geocronología limitó la edad de deposición de la formación a entre 2016 ± 6 y 1215 ± 20 millones de años.
- Los restos fósiles indican la presencia de organismos biológicos, productores de moco y móviles.
Conclusiones:
- Las impresiones discoidales son significativamente más antiguas de lo que se pensaba anteriormente, y son anteriores a la biota Ediacaran.
- Si bien los orígenes no biológicos de las impresiones son posibles, los restos fósiles confirman la actividad biológica de antiguos organismos vermiformes.
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