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Increased production of cosmogenic 10Be recorded in oceanic sediment sequences: Information on the age, duration, and amplitude of the geomagnetic dipole moment minimum over the Matuyama–Brunhes transition
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 δ18 O (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−2 s−1 that 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±0.4×10 22 Am2, in agreement with model simulations and absolute paleointensities of transitional lava flows.
Keyword(s)
authigenic Be-10/Be-9 ratio, geomagnetic dipole moment minimum, Matuyama-Brunhes transition (MBT), geomagnetic polarity reversal, marine isotope stage 19, atmospheric Be-10 production rates
Full Text
File | Pages | Size | Access | |
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Publisher's official version | 12 | 3 Mo | ||
Table S1. AMS measurements, authigenic 10Be and 9Be concentrations and authigenic 10Be/9Be ratios of core MD95-2016 samples. | - | 46 Ko | ||
Table S2. AMS measurements, authigenic 10Be and 9Be concentrations and authigenic 10Be/9Be ratios of core MD90-0961 samples. | - | 32 Ko | ||
Table S3. AMS measurements, authigenic 10Be and 9Be concentrations and authigenic 10Be/9Be ratios of core MD90-0949 samples. | - | 39 Ko | ||
Table S4. AMS measurements, authigenic 10Be and 9Be concentrations and authigenic 10Be/9Be ratios of core MD98-2183 samples. | - | 43 Ko | ||
Table S5. Correlation coefficients of Be-ratio versus 10Be and 9Be concentrations. | - | 9 Ko |