Multiband wavelet age modeling (MUBAWA) for a ~293 m (~600 kyr) sediment core from Chew Bahir basin, southern Ethiopian Rift
- 1Institute of Geoscience, University of Potsdam, Germany
- 2Safety Analyses Department, Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) GmbH, Forschungszentrum Garching, Germany, Germany
- 3Berkeley Seismology Laboratory, University of California, Berkeley, United States
- 4University of Cologne, Institute of Geography Education, Germany
- 5Potsdam Institute for Climate Impact Research (PIK), Germany
- 6University of Potsdam, Institute of Geoscience, Germany
The use of cyclostratigraphy to reconstruct the timing of deposition of lacustrine deposits requires sophisticated tuning techniques that can accommodate continuous long-term changes in sedimentation rates. However, most tuning methods use stationary filters that are unable to take into account such long-term variations in accumulation rates. To overcome this problem we present herein a new multiband wavelet age modeling (MUBAWA) technique that is particularly suitable for such situations and demonstrate its use on a 293 m composite core from the Chew Bahir basin, southern Ethiopian rift. In contrast to traditional tuning methods, which use a single, defined bandpass filter, the new method uses an adaptive bandpass filter that adapts to changes in continuous spatial frequency evolution paths in a wavelet power spectrum, within which the wavelength varies considerably along the length of the core due to continuous changes in longterm sedimentation rates. We first applied the MUBAWA technique to a synthetic data set before then using it to establish an age model for the approximately 293 m long composite core from the Chew Bahir basin. For this we used the 2nd principal component of color reflectance values from the sediment, which showed distinct cycles with wavelengths of 10-15 m and of ~40 m that were probably a result of the influence of orbital cycles. We used six independent 40 Ar/ 39 Ar ages from volcanic ash layers within the core to determine an approximate spatial frequency range for the orbital signal. Our results demonstrate that the new wavelet-based age modeling technique can significantly increase the accuracy of tuned age models.
Keywords: orbital forcing, African climate, Age modeling, Cyclostratigraphy, lake sediments
Received: 13 Aug 2020;
Accepted: 14 Jan 2021.
Copyright: © 2021 Düsing, Berner, Deino, Foerster, Kraemer, Marwan and Trauth. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Mx. Walter Düsing, University of Potsdam, Institute of Geoscience, Potsdam, Germany, firstname.lastname@example.org
Dr. Verena E. Foerster, University of Cologne, Institute of Geography Education, Cologne, Germany, V.Foerster@uni-koeln.de