Authigenic10Be/9Be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the Brunhes/Matuyama boundary.
Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium-10 (10Be) production rates. Authigenic10Be/9Be ratios (proxy of atmospheric10Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic10Be/9Be ratio results obtained from cores MD05-2920 and MD05-2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05-2920, MD05-2930 and MD90-0961 have been stacked and averaged. Variations of the authigenic10Be/9Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest10Be overproduction episodes are related to dipole field collapses (below a threshold of 2 × 1022Am2) associated with the Brunhes/Matuyama reversal, the Laschamp (41 ka) excursion, and the Iceland Basin event (190 ka). Other significant10Be production peaks are correlated to geomagnetic excursions reported in literature. The record was then calibrated by using absolute dipole moment values drawn from the Geomagia and Pint paleointensity value databases. The10Be-derived geomagnetic dipole moment record, independent from sedimentary paleomagnetic data, covers the Brunhes-Matuyama transition and the whole Brunhes Chron. It provides new and complementary data on the amplitude and timing of millennial-scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities.
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France; IPGP, Sorbonne Paris-Cité, Université Paris Diderot, UMR 7154, CNRS Paris France.
Quentin
Q
Simon
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France.
Nicolas
N
Thouveny
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France.
Didier L
DL
Bourlès
IPGP, Sorbonne Paris-Cité, Université Paris Diderot, UMR 7154, CNRS Paris France.
Jean-Pierre
JP
Valet
LSCE, UMR 8212, LSCE/IPSL, CEA-CNRS-UVSQ and Université Paris-Saclay Paris France.
Franck
F
Bassinot
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France.
Lucie
L
Ménabréaz
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France.
Valéry
V
Guillou
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France; IPGP, Sorbonne Paris-Cité, Université Paris Diderot, UMR 7154, CNRS Paris France.
Sandrine
S
Choy
CEREGE UM34, Aix-Marseille Université, CNRS, IRD, Collège de France Aix-en-Provence France.
Luc
L
Beaufort
10Be cosmogenic nuclide; Brunhes geomagnetic excursions; Brunhes/Matuyama transition; authigenic 10Be/9Be ratio; geomagnetic dipole lows; geomagnetic dipole moment