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El tiempo de los altos niveles del mar en los últimos 200.000 años
Science (New York, N.Y.)
|February 11, 1994
Resumen
La datación de coral con uranio y torio revela que los niveles del mar siguieron de cerca a la Tierra.
Área de la Ciencia:
- Geocronología Geocronología.
- Paleoclimatología Paleoclimatología
- Geología marina Geología marina.
Sus antecedentes:
- Los esqueletos de coral conservan registros isotópicos de las condiciones oceánicas pasadas.
- Comprender las fluctuaciones pasadas del nivel del mar es crucial para el modelado climático.
- La datación uranio-torio (U-Th) proporciona edades precisas para los carbonatos marinos.
Objetivo del estudio:
- Para determinar edades precisas de los corales de Barbados de los períodos de alto nivel del mar.
- Para reconstruir el pasado de los niveles del mar en los últimos 200.000 años.
- Para evaluar la precisión de los métodos de datación U-Th para corales antiguos.
Principales métodos:
- Análisis de las edades del torio-230 (230Th) y las proporciones de uranio-234/uranio-238 (234U/238U) en los corales fósiles.
- Evaluación del comportamiento de los isótopos de uranio y torio durante la diagenesis.
- Comparación de los picos del nivel del mar con los datos de insolación de verano del hemisferio norte.
Principales resultados:
- Establecido (230) Las edades de los corales que abarcan los últimos 200.000 años.
- Se confirmó la naturaleza prístina de algunas muestras de coral mediante la comparación de las relaciones iniciales (234) U / 238) U con los valores marinos modernos.
- Los picos observados del nivel del mar generalmente coinciden con o siguen a los picos de insolación de verano en el hemisferio norte.
- Documentó un retraso de 5.000 a 10.000 años en la caída del nivel del mar después de la disminución de la insolación durante períodos interglaciales e interestadios específicos.
Conclusiones:
- Los corales de Barbados proporcionan registros confiables del nivel del mar durante los últimos 200.000 años.
- La sincronización de los cambios del nivel del mar en el pasado apoya el forzamiento orbital de los ciclos glacial-interglacial.
- El modelado Diagenetic U-Th mejora la precisión de los datos geocronológicos de muestras marinas.
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