Cosmogenic signature of geomagnetic reversals and excursions from the Réunion event to the Matuyama–Brunhes transition (0.7–2.14 Ma interval)
Type | Article |
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Date | 2018-01 |
Language | English |
Author(s) | Simon Quentin1, 2, Bourles Didier L.1, Thouveny Nicolas1, Horng Chorng-Shern3, Valet Jean-Pierre2, Bassinot Franck4, 5, Choy Sandrine1, 2 |
Affiliation(s) | 1 : Aix Marseille Univ, CNRS, IRD, Coll France,CEREGE,UM34, F-13545 Aix En Provence, France. 2 : Univ Paris Diderot, Sorbonne Paris Cite, CNRS, IPGP,UMR 7154, 1 Rue Jussieu, F-75238 Paris, France. 3 : Acad Sinica, Inst Earth Sci, POB 1-55, Taipei, Taiwan. 4 : CNRS, UVSQ, CEA, LSCE,UMR8212,IPSL, Gif Sur Yvette, France. 5 : Univ Paris Saclay, Gif Sur Yvette, France. |
Source | Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2018-01 , Vol. 482 , P. 510-524 |
DOI | 10.1016/j.epsl.2017.11.021 |
WOS© Times Cited | 41 |
Keyword(s) | authigenic Be-10/Be-9 ratios, Matuyama-Brunhes transition, Jaramillo and Olduvai subchrons, Cobb Mountain and Reunion events, Matuyama geomagnetic excursions, lock-in depth |
Abstract | 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. |
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