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The effects of aliasing and lock-in processes on palaeosecular variation records from sediments

Teanby, N. and Gubbins, D. (2000) The effects of aliasing and lock-in processes on palaeosecular variation records from sediments. Geophysical Journal International, 142 (2). pp. 563-570. ISSN 0956-540X

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Studies of sedimentary records of palaeointensity variation report periods as long as 50 kyr. Archaeointensity data show geomagnetic periods of 2 kyr with large ampli-tudes. Sampling of the sedimentary records can be as coarse as 8 kyr, so the apparent long periods could be caused by aliasing. The sedimentary lock-in process could smooth the record and remove short periods, thereby preventing aliasing from occurring. We examine possible effects of aliasing by creating a 100-kyr-long synthetic sequence of palaeointensity variation with a similar spectrum to that of archaeomagnetic data from the last 12 kyr and resampling at longer intervals. With no lock-in smoothing,aliasing produces spurious energy in the spectra at long periods. When smoothing by the sedimentation process is applied, the amplitudes of the aliased peaks are reduced but still cause significant, spurious, long-period energy in the spectra for some sedi- mentation rates. We restrict our analysis to palaeointensity data but similar problems may also exist for coarsely sampled directional data. To avoid aliasing we recommend a maximum sampling interval of 2 kyr.

Item Type: Article
Copyright, Publisher and Additional Information: © 2000 RAS. This is an electronic version of an article published in Geophysical Journal International: complete citation information for the final version of the paper, as published in the print edition of Geophysical Journal International, is available on the Blackwell Synergy online delivery service, accessible via the journal's website at http://www.blackwellpublishing.com/journal.asp?ref=0956-540X or www.blackwell-synergy.com
Keywords: palaeointensity, palaeomagnetism, sediments, spectral analysis
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)
Depositing User: Sherpa Assistant
Date Deposited: 04 May 2005
Last Modified: 08 Jun 2014 19:19
Published Version: http://www.blackwell-synergy.com/
Status: Published
Refereed: Yes
Identification Number: 10.1046/j.1365-246x.2000.00180.x
URI: http://eprints.whiterose.ac.uk/id/eprint/426

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