@article{PAR00009555,
  title = {{A}mplitude and timing of the {L}aschamp geomagnetic dipole low from the global atmospheric {B}e-10 overproduction : contribution of authigenic {B}e-10/{B}e-9 ratios in west equatorial {P}acific sediments},
  author = {{M}enabreaz, {L}. and {B}ourles, {D}. {L}. and {T}houveny, {N}icolas},
  editor = {},
  language = {{ENG}},
  abstract = {{A}uthigenic {B}e-10/{B}e-9 ratios were measured along a sediment core collected in the west equatorial {P}acific in order to reconstruct cosmogenic {B}e-10 production variations near the equator, where the geomagnetic modulation is maximum. {F}rom 60 to 20 ka, the single significant {B}e-10 production impulse recorded at 41 ka results from the geomagnetic dipole low that triggered the {L}aschamp excursion. {N}o significant {B}e-10 overproduction signature is recorded at the age of the {M}ono {L}ake excursion (similar to 34 ka). {A} compilation of authigenic {B}e-10/{B}e-9 records obtained from sediments was averaged over a 1 kyr window and compared with the 1 kyr averaged {B}e-10 flux record of {G}reenland ice cores. {T}heir remarkable similarity demonstrates that {B}e-10 production is globally modulated by geomagnetic dipole variations and redistributed by atmosphere dynamics. {A}fter calibration using absolute values of the virtual dipole moment drawn from paleomagnetic database, the authigenic {B}e-10/{B}e-9 stack allows reconstructing the geomagnetic dipole moment variations over the 20-50 ka time interval. {B}etween 48 and 41 ka, the dipole moment collapsed at a rate of -1.5 x 10(22) {A} m(2) kyr(-1), which will be an interesting criterion for the assessment of the loss rate of the historical field and the comparison of dipole moment loss prior to excursions and reversals. {A}fter a 2 kyr duration of the minimum dipole moment (similar to 1 x 10(22) {A} m(2)), a slow increase started at 39 ka, progressively reaching 5 x 10(22) {A} m(2) at 20 ka. {T}he absence of a significant dipole moment drop at 34 ka, the age of the {M}ono lake excursion, suggests that the duration and amplitude of the dipole weakening cannot be compared with that of the {L}aschamp. {T}his study provides a reliable basis to model the production of radiocarbon and in situ cosmogenic nuclides and to improve the calibration of these dating methods.},
  keywords = {},
  booktitle = {},
  journal = {{J}ournal of {G}eophysical {R}esearch. {S}olid {E}arth},
  volume = {117},
  numero = {},
  pages = {{B}11101},
  ISSN = {0148-0227},
  year = {2012},
  DOI = {10.1029/2012jb009256},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00009555},
}