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Oscilaciones inducidas orbitalmente en la capa de hielo de la Antártida Oriental en el límite entre el Oligoceno y el
T R Naish1, K J Woolfe, P J Barrett
1Institute of Geological and Nuclear Sciences, PO Box 30368, Lower Hutt, New Zealand. t.naish@gns.cri.nz
Nature
|October 19, 2001
Resumen
Las capas de hielo de la Antártida fluctuaron con los ciclos orbitales durante la transición Oligoceno / Mioceno. Los núcleos de sedimentos revelan vínculos directos entre la capa de hielo de la Antártida Oriental.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- La paleoceanografía es la paleoceanografía.
- Ciencias del clima Ciencias del clima Ciencias del clima
Sus antecedentes:
- Las capas de hielo antárticas pueden haber sido inestables hace 34-15 millones de años (Myr) durante un clima más cálido con niveles más altos de CO2.
- Los registros de isótopos de oxígeno sugieren que los ciclos orbitales influyeron en las temperaturas globales y los volúmenes de hielo, pero faltaba evidencia directa de las oscilaciones de la capa de hielo antártica.
Objetivo del estudio:
- Para calibrar los cambios inferidos en el volumen de hielo antártico con evidencia directa de las oscilaciones de la capa de hielo.
- Para vincular la extensión de la capa de hielo de la Antártida Oriental directamente a los ciclos orbitales durante la transición Oligoceno / Mioceno.
Principales métodos:
- Análisis de datos de sedimentos de núcleos marinos poco profundos en el oeste del Mar de Ross.
- Datación de las secuencias glacimarinas y hiatos erosionales utilizando un modelo de edad.
- Correlación de los cambios en el volumen de hielo con los ciclos orbitales (oblicuidad y excentricidad).
Principales resultados:
- Las variaciones cíclicas bien fechadas en los núcleos de sedimentos vinculan directamente la extensión de la capa de hielo de la Antártida Oriental con los ciclos orbitales (hace 24.1-23.7 millones de años).
- Las secuencias de glacimarina rápidamente depositadas, restringidas a <450 kyr, indican frecuencias de oblicuidad (40 kyr) y excentricidad (125 kyr) de las oscilaciones controladas del margen de hielo.
- Un hiato erosional (250 kyr) proporciona evidencia directa de un importante evento de enfriamiento global y expansión de la capa de hielo (Mi1) hace alrededor de 23.7 millones de años.
Conclusiones:
- Los ciclos orbitales influyeron significativamente en la dinámica de la capa de hielo antártica durante la transición Oligoceno / Mioceno.
- El estudio proporciona evidencia directa del impacto del forzamiento orbital en el comportamiento de la capa de hielo en la Antártida Oriental.
- Los hallazgos corroboran las inferencias anteriores de un importante evento de enfriamiento y expansión del hielo (Mi1) hace 23.7 millones de años.
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