Reconstruction of geomagnetic dipole moment variations for the last glacial period based on cosmogenic radionuclides from Greenland ice cores
- 1Department of Geology, Lund University, Lund, Sweden (minjie.zheng@geol.lu.se)
- 2Department of Earth Sciences, Uppsala University, Uppsala, Sweden
- 3Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
- 4Department of Geology, United Arab Emirates University, Al Ain, United Arab Emirates
- 5Tandem Laboratory, Uppsala University, Uppsala, Sweden
Geomagnetic dipole moment variations, for example associated with polarity reversals and excursions, are linked to changes in cosmogenic radionuclide production rates. Therefore, it is possible to reconstruct past changes in the dipole moment based on cosmogenic radionuclide records from natural archives such as ice cores. Here we present a geomagnetic dipole moment reconstruction based on 10Be and 36Cl data from two Greenland ice cores over the period from 11.7 ka to 108 ka BP (before present AD 1950). We find significant correlations between the cosmogenic radionuclides and climate proxies which may be due to the common transport and deposition processes of these species. In an attempt to minimize climate-related variations in our dipole moment reconstruction, we apply a multi-linear correction method by removing common variability between 10Be and 36Cl and climate parameters (accumulation, δ18O and aerosol data) from the radionuclide records. The comparison of the resulting cosmogenic radionuclide-based dipole reconstruction with independent geomagnetic field records shows good agreement. This validates the use of cosmogenic radionuclides in ice cores to reconstruct past geomagnetic dipole moment variations after correction for the climate effect.
How to cite: Zheng, M., Sturevik-Storm, A., Nilsson, A., Adolphi, F., Aldahan, A., Possnert, G., and Muscheler, R.: Reconstruction of geomagnetic dipole moment variations for the last glacial period based on cosmogenic radionuclides from Greenland ice cores, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1652, https://doi.org/10.5194/egusphere-egu2020-1652, 2019