Climatic influence in NRM and Be-10-derived geomagnetic paleointensity data

One can determine geomagnetic paleointensities from natural remanent magnet izations (NRM) and by inverting production rates of cosmogenic isotopes suc h as Be-10 and C-14. Recently, two independently derived 200-kyr stacks [Y. Guyodo, J.-P. Valet, Relative variations in geomagnetic intensity from sed imentary records: the past 200,000 years, Earth Planet. Sci. Lett. 143 (199 6) 23-36; M. Frank, B. Schwarz, S. Baumann, P.W. Kubik, M. Suter, A. Mangin i, A 200 kyr record of cosmogenic radionuclide production rate and geomagne tic field intensity from Be-10 in globally stacked deep-sea sediments, Eart h Planet. Sci. Lett. 149 (1997) 121-129] were compared and the good agreeme nt was suggested to validate the use of sedimentary cores for studies. Both compilations use mainly the astronomically forced and climatically control led oxygen isotope stratigraphy to date and synchronize the sedimentary rec ords, while this very curve has several coherent features with the supposed ly pure geomagnetic records. An NRM relative paleointensity record, which w as included in the conventional paleointensity stack, shows correspondence with climatic features, which is explained by an inadequacy in the normaliz ation technique. Therefore, it is possible that the extraction of the pure paleointensity signal from marine sediments has not always been accomplishe d. (C) 1999 Elsevier Science B.V. All rights reserved.