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30.000 años de polvo cósmico en el hielo antártico

Gisela Winckler¹, Hubertus Fischer

¹Lamont-Doherty Earth Observatory (L-DEO), Earth Institute at Columbia University, Palisades, NY 10964, USA. winckler@ldeo.columbia.edu

Science (New York, N.Y.)

|July 29, 2006

Resumen

Los registros de polvo cósmico de los núcleos de hielo de la Antártida muestran un flujo constante de helio-3 durante 30.000 años, lo que lo descarta como un impulsor de los ciclos glaciales. Esto apoya el helio-3 como un proxy paleoclimático estable.

Área de la Ciencia:

Paleoclimatología Paleoclimatología
Estudios del polvo cósmico Estudios del polvo cósmico
La geoquímica de los isótopos es la geoquímica de los isótopos.

Sus antecedentes:

Los núcleos de hielo polar conservan la histórica afluencia de polvo cósmico.
Los isótopos de helio (3He y 4He) se utilizan como proxies para el polvo cósmico.
El Proyecto Europeo para el Corazón de Hielo en la Antártida (EPICA) proporciona valiosos datos de núcleos de hielo.

Objetivo del estudio:

Para reconstruir un registro glacial-interglacial de polvo cósmico de alta resolución.
Para investigar el papel del flujo de helio-3 (3He) en los ciclos glaciales del Pleistoceno tardío.
Para identificar los cambios en las fuentes de polvo terrestre entre los períodos glaciales e interglaciales.

Principales métodos:

Análisis de isótopos de helio de alta resolución (3He y 4He).
Análisis del núcleo de hielo EPICA de la Tierra de Dronning Maud, en la Antártida.
Medición del calcio de sales no marinas (Ca2+) para evaluar la contribución del polvo terrestre.

Principales resultados:

Se ha observado un flujo de 3He relativamente constante durante los últimos 30.000 años.
Se descubrió que el flujo de 3He era independiente de los ciclos glacial-interglacial.
Se detectó un cambio en la relación 4He/sal no marina Ca2+ desde el último período glacial hasta el Holoceno.

Conclusiones:

El helio-3 no es un marcapasos para los ciclos glaciales del Pleistoceno tardío.
El helio-3 sirve como un parámetro de flujo constante confiable para estudios paleoclimáticos.
El cambio observado en la relación 4He/sal no marina Ca2+ sugiere cambios en las fuentes de polvo terrestre durante las transiciones climáticas.

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