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Registro climático continuo de 500,000 años a partir de calcita de vena en el agujero del diablo, Nevada
Science (New York, N.Y.)
|October 9, 1992
Resumen
Los registros paleoclimáticos de Devils Hole, Nevada, revelan una historia de temperatura de 500,000 años. Este registro continental desafía la hipótesis de Milankovitch, sugiriendo que las retroalimentaciones del sistema climático interno impulsan los ciclos glaciales.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- La geoquímica es la geoquímica.
- Geología Cuaternaria Geología Cuaternaria
Sus antecedentes:
- El análisis del isótopo de oxígeno (delta 18 O) de los archivos paleoclimáticos proporciona información sobre la temperatura pasada y el volumen de hielo.
- El núcleo de calcita de Devils Hole (DH-11) ofrece un registro único y continuo de paleotempera continental.
Objetivo del estudio:
- Para reconstruir un registro de paleotemperatura a largo plazo de Devils Hole, Nevada.
- Para comparar este registro continental con los archivos de paleoclima marino y antártico establecidos.
- Investigar los impulsores de los ciclos glaciales del Pleistoceno y probar la hipótesis de Milankovitch.
Principales métodos:
- Análisis del isótopo del oxígeno (delta(18) O) de un núcleo de calcita en una vena de 36 cm (DH-11).
- Datación cronológica utilizando 21 replicadas fechas de la serie de uranio espectrométrico de masas.
- Comparación del registro de Devils Hole con el núcleo de hielo de Vostok y los registros del delta marino.
Principales resultados:
- Se estableció un registro ininterrumpido de paleotemperatura de 500,000 años.
- El registro coincide estrechamente con las principales características de Vostok y los registros de volumen de hielo marino.
- Las duraciones del ciclo glacial variaron significativamente (80.000 a 130.000 años), lo que indica la aperiodicidad.
- Los períodos interglaciales duraron aproximadamente 20.000 años.
- Las deglaciaciones no fueron desencadenadas principalmente por variaciones de insolación orbital.
Conclusiones:
- El registro de paleotemperatura de Devils Hole desafía la hipótesis de Milankovitch como el único impulsor de los ciclos glaciales del Pleistoceno.
- La dinámica observada del ciclo glacial es consistente con las retroalimentaciones internas no lineales dentro del sistema climático de la Tierra (atmósfera-capa de hielo-océano).
- Los principales cambios climáticos parecen ser aperiódicos, impulsados por interacciones complejas de sistemas en lugar de forzar únicamente órbitas externas.
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