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| Titel |
Extended record of 10Be at EPICA Dome C during the last 800 000 years and its synchronization with geomagnetic paleointensity variations from marine sediments |
| VerfasserIn |
Alexandre Cauquoin, Grant Raisbeck, Jean Jouzel, Edouard Bard, Aster Team |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081860
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| Zusammenfassung |
| Polar ice cores are exceptional archives that permit the reconstruction of many parameters
(variations of temperature, atmospheric composition-¦) and the reconstitution of the past
variations of the Earth climate and environment. They also give access to beryllium-10 (10Be)
fallout, an isotope of cosmogenic origin, created by the interaction of Galactic Cosmic Rays
(GCR, constituted of high energy charged particles) with the upper atmosphere. The
cosmic rays being modulated by solar activity and Earth’s magnetic field intensity,
the 10Be production is inversely related to the intensity of these two parameters.
Most 10Be produced is quickly removed from the atmosphere (residence time in the
stratosphere ~1-2 years) and, on the Antarctic plateau, falls mainly by dry deposition as
aerosols.
So, 10Be can be used as a proxy of paleointensity. It has allowed the improvement of ice cores
chronologies thanks to absolute stratigraphic markers linked to excursions and inversions of
the geomagnetic field such as the Laschamp excursion [1] or the Matuyama-Brunhes reversal
[2, 3].
EPICA Dome C (75° 06’ S, 123° 21’ E) is a 3270 meter ice core drilled in East Antarctica in
the framework of an international project. It offers a complete climate record over the
last 800 000 years. As shown at the IPICS 2012 meeting, for the 355 – 800 ka
period [4], a continuous high-resolution (11 cm) 10Be profile in this core can be
synchronized with continuous variations of paleointensity (PISO-1500) recorded in
marine sediments [5] in order to obtain a continuous relative chronology of climate
proxies (δD and δ18O respectively) for these two reservoirs. Here, we extend this
synchronization down to 269 ka, thus including termination IV and interstadial MIS
9.
[1]. Raisbeck et al. (2007) Clim.Past, 3, 541 – 547.
[2]. Raisbeck et al. (2006) Nature, 444, 82 – 84.
[3]. Dreyfus et al. (2008) Earth and Planet. Sci. Lett., 274, 151 – 156.
[4]. G.Raisbeck et al. (2012) IPICS Open Science Conference, October 2012, Presqu’ïle de
Giens, France.
[5]. Channell et al. (2009) Earth and Planet. Sci. Lett., 283, 14 – 23. |
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