DOI 10.1016/j.epsl.2017.11.021 Long-term variations of the geomagnetic dipole moment (GDM) during periods of stable polarity and in transitional states (reversals and excursions) provide key information for understanding the geodynamo regime. Following several studies dealing with the Brunhes chron and the Matuyama–Brunhes transition, this study presents a new authigenic 10Be/9Be ratio (Be-ratio) record obtained from the MD97-2143 core (western Pacific Ocean). This new Be-ratio series yields a record of GDM variations covering the early Brunhes and mid to late Matuyama time period (i.e. 700–2140ka), independently from the relative paleointensity (RPI) record obtained from the same core, that can be compared with available RPI records and stacks. Stratigraphic offsets measured between the Be-ratio peaks and the corresponding RPI minima reach 2 to 14cm. They can be assigned to (post-) detrital remanent magnetization (pDRM) effects leading to magnetization locking-in delays varying from 2 to 12ka in the studied core. 10Be overproduction episodes triggered by geomagnetic dipole moment lows (GDL) linked to polarity reversals and excursions confirm the global control exerted by the GDM on cosmogenic radionuclides production. A dipole moment reconstruction derived from the Beryllium-10 (BeDiMo) was compiled and calibrated using absolute paleointensity data. This independent record complements the available paleomagnetic RPI records, permitting 1) to overcome the pDRM lock-in offsets induced below the mixing layer, 2) to confront and increase the robustness and precision of GDM reconstructions and, 3) to better constrain the chronology of geomagnetic field instabilities during the mid to late Matuyama chron. Our new 10Be derived inventory is fully compatible with the GDL series linked to geomagnetic polarity reversals and events (Matuyama–Brunhes transition, Jaramillo and Olduvai subchron boundaries, Cobb Mountain, Réunion) and it strengthens the occurrence of several excursions (Kamikatsura, Santa Rosa, Punaruu, Bjorn, Gilsa, Gardar) that were until now reported from only sparse locations.
authigenic Be-10/Be-9 ratios, Matuyama-Brunhes transition, Jaramillo and Olduvai subchrons, Cobb Mountain and Reunion events, Matuyama geomagnetic excursions, lock-in depth
| File | Pages | Size | Access | |
|---|---|---|---|---|
Publisher's official version | 15 | 2 Mo | ||
Table S1. AMS measurements, authigenic 10Be and 9Be concentrations and authigenic 10Be/9Be ratios of core MD97-2143 samples. | - | 60 Ko | ||
Table S2. Correlation coefficients between the BeDiMo and references. | - | 9 Ko | ||
Table S3. Average VADM values for selected time intervals: Brunhes vs mid- to late-Matuyama. | - | 9 Ko | ||
Table S4. Glossary of abbreviations. | - | 9 Ko | ||
Fig. S1. Benthic δ18O record of core MD97-2143 in red (Horng et al., 2002) is compared to the LR04 benthic stack of Lisiecki and Raymo (2005) in blue. The Cibicides wuellerstorfi δ18O data ... | 1 | 268 Ko | ||
Fig. S2. Empirical calibration of the normalized authigenic 10Be/9Be ratio stack using absolute paleointensity (PI) values extracted from the Geomagia50.v3 ... | 1 | 144 Ko | ||
Fig. S3. BeDiMo compared to all available absolute intensities from the PINT2015-05 database (Biggin et al., 2009). Red dots... | 1 | 1 Mo | ||
Fig. S4. Comparison of the BeDiMo with RPI stacks. All RPI-series were standardized and aligned on the BeDiMo time scale using GDL. | 1 | 1 Mo |
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