Magnetic susceptibility and radioactivity changes of aegean and ionian sea sediments during last glacial/interglacial: Climatic and chronological markers

摘要

Five marine sediment boreholes from the Aegean and Ionian Sea have been measured here for their magnetic susceptibility and (in an earlier work) by alpha-and beta-particle radioactivity. The corresponding borehole cores cover the Holocene period and closely spaced data have been sampled from all cores. The obtained depth data series have been converted here to the time series by using appropriate conversions on the basis of sedimentation rates derived from dating of selected samples of each core. The spectral characteristics of the new statistical elaboration for the final time series exhibit a significant correlation of the magnetic susceptibility and radioactivity data. This correlation is prominent especially for intermediate periods (typically 110 ky) of the examined spectra and tends to disappear for higher frequency variations (<1 ky), suggesting that mainly long-period climatic and other changes are the ones that affect the examined quantities in a similar manner. This pattern is verified by the band-pass filtered time series for intermediate periods, which reveals well-correlated susceptibility and radioactivity changes. In addition, specific time markers are observed in the filtered time series, and comparison of their variation to certain climatic phases within the Holocene is recognized.