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Estratigrafía de isótopos de hafnio de las costras de ferromanganeso
1Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA. Institut fur Isotopengeologie und Mineralische Rohstoffe, Department fur Erdwissenschaften, ETH-Zentrum, NO C61, Sonneggstrasse 5, CH-8092 Zurich, Switzerland.
Science (New York, N.Y.)
|August 14, 1999
Resumen
Los isótopos de hafnio de aguas profundas del Pacífico Central muestran importantes fluctuaciones del Eoceno-Oligoceno, posiblemente por advección oceánica. Durante los últimos 20 millones de años, las composiciones isotópicas del hafnio se mantuvieron uniformes, lo que sugiere un mayor aislamiento del Pacífico.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Oceanografía La oceanografía es la oceanografía.
- La paleoceanografía es la paleoceanografía.
Sus antecedentes:
- Las costras de ferromanganeso proporcionan valiosos archivos de la química oceánica del pasado.
- Comprender la circulación oceánica del Cenozoico y la composición isotópica es crucial para las reconstrucciones paleoclimáticas.
Objetivo del estudio:
- Para reconstruir la historia del Cenozoico de las composiciones isotópicas de hafnio (Hf) en aguas profundas del Pacífico central.
- Para investigar la influencia de los cambios en la circulación oceánica en los registros isotópicos de Hf de aguas profundas.
Principales métodos:
- Análisis de las composiciones isotópicas de Hf de dos costras de ferromanganeso geográficamente separadas que abarcan el Cenozoico.
- Comparación de los datos isotópicos de Hf con eventos oceanográficos y geológicos conocidos.
Principales resultados:
- Las costras de ferromanganeso revelan variaciones seculares similares en los isótopos de Hf a pesar de estar a más de 3000 km de distancia.
- Se produjeron importantes fluctuaciones isotópicas de Hf durante el Eoceno y el Oligoceno, potencialmente vinculadas a la advección desde los océanos Índico y Atlántico.
- Las composiciones isotópicas de Hf se mantuvieron relativamente constantes durante los últimos 20 millones de años, lo que indica un mayor aislamiento del Pacífico central.
Conclusiones:
- La composición isotópica de Hf en aguas profundas del Pacífico Central ha variado significativamente en respuesta a cambios oceanográficos pasados.
- La uniformidad a largo plazo en los isótopos de Hf en los últimos 20 millones de años apunta a un Pacífico central más aislado.
- Los mecanismos que impulsan las variaciones isotópicas del estroncio (Sr) en el agua de mar no tuvieron un impacto significativo en los isótopos de Hf de aguas profundas del Pacífico central durante el Cenozoico.
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