HR: 1340h
AN: GP43A-0931    [Abstracts]
TI: A Wavelet Approach of Determining the Origin of Orbital Periods in Relative Paleointensity Records
AU: * Xuan, C
EM: xuan2005@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611, United States
AU: Channell, J E
EM: jetc@geology.ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611, United States
AB: Power spectral analysis and continuous wavelet analysis with significance tests were applied to four relative paleointensity (RPI) records and their normalizer records from both North Atlantic (ODP sites 983 and 984) and North Pacific Ocean (NGC65 and NGC69). The results indicate the presence of significant power at 100 kyr and 41 kyr periods in these records during certain time intervals. Significant common power at orbital periods has been detected between the RPI records and their normalizer records for specific intervals in all these records using cross wavelet analysis. Squared wavelet coherence between the RPI records and their normalizer records further indicate that the two types of records are significantly coherent at orbital periods in specific time intervals. Squared wavelet coherence between RPI records from different climate regimes show out phase relationship on orbital periods during intervals where significant power of orbital periods were observed in the RPI records, and in phase relationship on orbital periods during other intervals. We conclude that orbital cycles detected in the paleointensity records are due to incomplete normalization of the natural remanent magnetization (NRM) records for changes in magnetic concentration and grain-size. Two lines of evidence indicate that the lithologic contamination, although present, does not debilitate the paleointensity records: (1) RPI records can be satisfactorily correlated across differing climatic regimes such as from the North Atlantic to Pacific oceans, and (2) filtering the orbital power from the time series does not appreciably alter the RPI records.
DE: 1521 Paleointensity
DE: 1560 Time variations: secular and longer
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting