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Episodios glaciales de un océano Ártico de agua dulce cubierto por una gruesa plataforma de hielo
Walter Geibert1, Jens Matthiessen2, Ingrid Stimac2
1Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany. walter.geibert@awi.de.
Nature
|February 4, 2021
Resumen
La evidencia revela dos grandes intervalos de agua dulce del Ártico bajo extensas plataformas de hielo, impactando las condiciones oceánicas pasadas y los registros del nivel del mar. Esto desafía las interpretaciones anteriores de la historia glacial del Ártico.
Área de la Ciencia:
- Paleoceanografía
- Geología marina
Sus antecedentes:
- Las primeras hipótesis sugirieron que las plataformas de hielo del Ártico pasaron, apoyadas por características de erosión en el nivel del mar.
- Los registros de sedimentos marinos carecían de evidencia definitiva de extensas plataformas de hielo del Ártico durante los períodos glaciales.
Objetivo del estudio:
- Proporcionar evidencia directa de sedimentos marinos para extensas plataformas de hielo del Ártico y intervalos de agua dulce.
- Investigar el momento y las implicaciones de estos eventos en las condiciones del Océano Ártico.
- Para explicar las anomalías en los registros de torio-230 y las tasas de sedimentación.
Principales métodos:
- Análisis de núcleos de sedimentos marinos para las firmas isotópicas, en particular el torio-230.
- Caracterización de nanofósiles calcáricos, incluida la Emiliania huxleyi.
- Estimaciones del flujo hidrológico y análisis de las condiciones límite.
Principales resultados:
- Evidencia de al menos dos grandes intervalos de agua dulce del Ártico que coinciden con la presencia extensa de plataformas de hielo.
- La datación de estos intervalos es de 70.000 a 62.000 años BP (etapa de isótopos marinos 4) y de 150.000 a 131.000 años BP (etapa de isótopos marinos 6).
- Explicación de los mínimos generalizados en los registros de torio-230, resolviendo las discrepancias de datación.
Conclusiones:
- El Océano Ártico estaba cubierto por plataformas de hielo y lleno de agua dulce durante períodos glaciales específicos.
- Estos eventos involucraron aproximadamente nueve millones de kilómetros cúbicos de agua dulce, desafiando las reconstrucciones existentes del nivel del mar.
- La liberación significativa de agua dulce al Océano Atlántico Norte es plausible en escalas de tiempo cortas.
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