236 articles – 3604 Notices  [english version]
HAL : in2p3-00138066, version 1

Fiche détaillée  Récupérer au format
Nature 444 (2006) 82-84
$^{10}$Be evidence for the Matuyama-Brunhes geomagnetic reversal in the EPICA Dome C ice core
G.M. Raisbeck1, F. Yiou1, O. Cattani2, J. Jouzel2

An ice core drilled at Dome C, Antarctica, is the oldest ice core so far retrieved 1. On the basis of ice flow modelling and a comparison between the deuterium signal in the ice with climate records from marine sediment cores, the ice at a depth of 3,190 m in the Dome C core is believed to have been deposited around 800,000 years ago 2, offering a rare opportunity to study climatic and environmental conditions over this time period. However, an independent determination of this age is important because the deuterium profile below a depth of 3,190 m depth does not show the expected correlation with the marine record 2. Here we present evidence for enhanced 10Be deposition in the ice at 3,160-3,170 m, which we interpret as a result of the low dipole field strength during the Matuyama-Brunhes geomagnetic reversal, which occurred about 780,000 years ago. If correct, this provides a crucial tie point between ice cores, marine cores and a radiometric timescale.
1 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
2 :  LSCE - UMR 8212 - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]

Planète et Univers/Sciences de la Terre/Géophysique

Planète et Univers/Sciences de la Terre/Climatologie

Planète et Univers/Sciences de la Terre/Glaciologie