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Un registro climático de 250.000 años de la calcita de la vena de la gran cuenca: implicaciones para la teoría de
Science (New York, N.Y.)
|December 2, 1988
Resumen
Un registro continuo de variaciones continentales de oxígeno-18 (delta(18) O) de la Gran Cuenca sugiere que la última etapa interglacial comenzó significativamente antes de lo que se databa anteriormente. Esto desafía las cronologías marinas existentes y el papel principal del forzamiento orbital en las edades de hielo del Pleistoceno.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- La geoquímica es la geoquímica.
- Geología Cuaternaria Geología Cuaternaria
Sus antecedentes:
- Comprender la dinámica climática del Pleistoceno es crucial para reconstruir la historia climática de la Tierra.
- Los registros de isótopos de oxígeno (delta 18 O) de sedimentos marinos y núcleos de hielo proporcionan información clave sobre la variabilidad climática pasada.
- Las cronologías existentes para los eventos climáticos del Pleistoceno, particularmente la etapa 5 del isótopo de oxígeno marino, se basan en métodos de datación indirectos.
Objetivo del estudio:
- Establecer un registro continuo, fechado de forma independiente, de las variaciones de oxígeno-18 en la hidrosfera continental durante el Pleistoceno medio y tardío.
- Para comparar la cronología de los eventos climáticos derivados del registro continental con los registros marinos y de núcleos de hielo establecidos.
- Investigar posibles revisiones necesarias para las cronologías existentes de isótopos de oxígeno marino y volver a evaluar los impulsores de las edades de hielo del Pleistoceno.
Principales métodos:
- La datación por series de uranio (U-Th) de una vena calcítica de Devils Hole, Nevada, fue encontrada en el año 2000.
- Análisis de las variaciones de oxígeno-18 (delta(18) O) en la vena calcítica, que representa las aguas subterráneas continentales.
- Comparación de las series de tiempo del delta derivado con el delta del núcleo de hielo marino y antártico (Vostok). registros.
Principales resultados:
- Se generó un registro de delta continuo de la Gran Cuenca del sur que abarca de hace 50 a 310 mil años (ka).
- La curva del delta continental muestra similitudes pero discrepancias de tiempo significativas con los registros de núcleos de hielo marinos y Vostok.
- La última etapa interglacial (etapa 5 del isótopo de oxígeno marino) está fechada antes de 147 +/- 3 ka, sustancialmente antes de lo que sugieren los registros marinos.
Conclusiones:
- El registro de la hidrosfera continental indica que las cronologías de isótopos de oxígeno marino pueden requerir revisión.
- El calendario de los principales eventos climáticos del Pleistoceno puede diferir de las interpretaciones actuales basadas en registros marinos.
- El forzamiento orbital podría no ser el único o principal impulsor de las edades de hielo del Pleistoceno, lo que sugiere que otros factores están involucrados.
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