ausblenden:
Schlagwörter:
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Zusammenfassung:
New high-resolution authigenic
10Be/9Be ratio (Be-ratio) records covering the last geomagnetic reversal,
i.e. the Matuyama–Brunhes transition (MBT), have been obtained and set on a time scale using benthic
δ18O (Cibicides wuellerstorfi) records. The geographic distribution of the four studied sites allows global
comparison between the North Atlantic, Indian and Pacific Oceans. All Be-ratio records contain a two-
fold increase triggered by the geomagnetic dipole moment (GDM) collapse associated with the MBT. The
stratigraphic position of the Be-ratio spike, relative to marine isotope stages, allows establishment of a
robust astrochronological framework for the MBT, anchoring its age between 778 and 766 ka (average
mid-peaks at 772 ka), which is consistent with all other available
10Be-proxy records from marine, ice
and loess archives. The global
10Be atmospheric production doubling represents an increase of more than
300 atoms m−2s−1that is compatible with the increased magnitude of atmospheric
10Be production
obtained by simulations between the present GDM and a null-GDM. The minimum
10Be-derived GDM
average computed for the 776–771 ka interval is 1.7 ±0.4 ×1022 Am2, in agreement with model
simulations and absolute paleointensities of transitional lava flows.
