In-phase anomalies in Beryllium-10 production and palaeomagnetic field behaviour during the Iceland Basin geomagnetic excursion |
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| Authors: | Mads Faurschou Knudsen Gideon M Henderson Martin Frank Conall Mac Niocaill Peter W Kubik |
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| Institution: | 1. Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom;2. IfM-GEOMAR, Leibniz Institute for Marine Sciences, University of Kiel, Germany;3. Paul Scherrer Institut, c/o Institute of Particle Physics, ETH Zurich, Switzerland;1. Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark;2. Department of Geoscience, Aarhus University, Aarhus, Denmark;4. Paul Scherrer Institut, Villigen, Switzerland;5. Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland;6. Department of Earth Sciences, Uppsala University, Sweden;7. Department of Geology, United Arab Emirates University, Al Ain, United Arab Emirates;8. Tandem Laboratory, Uppsala University, Sweden;1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA;2. Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA;3. Geological Institute, Department of Earth Sciences, ETH Zürich, Switzerland;4. Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada;5. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;1. CEREGE UM34, Aix Marseille Univ, CNRS, IRD, Coll France, Aix en Provence, France;2. IPGP, Université Paris Diderot, Sorbonne Paris-Cité, UMR 7154 CNRS, 75238 Paris, France;3. Laboratoire des Sciences du Climat et de L''Environnement, UMR8212, LSCE/IPSL, CEA-CNRS-UVSQ and Université Paris-Saclay, Gif-Sur-Yvette, France;4. Department of Earth and Geoenvironmental Science, University of Bari Aldo Moro, E. Orabona 4, 70125 Bari, Italy |
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| Abstract: | Increases in the production rate of cosmogenic radionuclides associated with geomagnetic excursions have been used as global tie-points for correlation between records of past climate from marine and terrestrial archives. We have investigated the relative timing of variations in 10Be production rate and the corresponding palaeomagnetic signal during one of the largest Pleistocene excursions, the Iceland Basin (IB) event (ca. 190 kyr), as recorded in two marine sediment cores (ODP Sites 1063 and 983) with high sedimentation rates. Variations in 10Be production rate during the excursion were estimated by use of 230Thxs normalized 10Be deposition rates and authigenic 10Be/9Be. Resulting 10Be production rates are compared with high-resolution records of geomagnetic field behaviour acquired from the same discrete samples. We find no evidence for a significant lock-in depth of the palaeomagnetic signal in these high sedimentation-rate cores. Apparent lock-in depths in other cores may sometimes be the result of lower sample resolution. Our results also indicate that the period of increased 10Be production during the IB excursion lasted longer and, most likely, started earlier than the corresponding palaeomagnetic anomaly, in accordance with previous observations that polarity transitions occur after periods of reduced geomagnetic field intensity prior to the transition. The lack of evidence in this study for a significant palaeomagnetic lock-in depth suggests that there is no systematic offset between the 10Be signal and palaeomagnetic anomalies associated with excursions and reversals, with significance for the global correlation of climate records from different archives. |
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