Power Spectrum Analyses of Storm Layers in Marine Silty Sediments: A Tool for a Paleoclimatic Reconstruction?
Keywords:Marine geology, Holocene, Baltic Sea, X-radiographs, time series analyses
Climatic events are imprinted on the sedimentary record of the Baltic Sea. In these sediments, storm events are documented by sandy horizons within the mud sequences which dominate the deeper basins. The spectral characteristics of the storm layer sequences were determined through analyses of the optical density of sediment X-radiographs. Previously the evaluation of X-radiographs was done visually and provided qualitative rather than quantitative information. In order to enable a more objective analysis, an optical scanner was developed. Subsequently the digitized sequence was analysed using Fast Fourier Transformation procedures. The results show that the observed cycles which lead to the formation of alternating layers can be attributed to calendar and solar band frequency variations.