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Influence of data filters on the accuracy and precision of paleomagnetic poles: what is the optimal sampling strategy?
  • Dieke Gerritsen,
  • Bram Vaes,
  • Douwe J.J. van Hinsbergen
Dieke Gerritsen
Utrecht University

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Bram Vaes
Utrecht University
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Douwe J.J. van Hinsbergen
Utrecht University
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Abstract

To determine a paleopole, the paleomagnetic community commonly applies a loosely defined set of quantitative data filters that were established for studies of geomagnetic field behavior. These filters require costly and time-consuming sampling procedures, but whether they improve accuracy and precision of paleopoles has not yet been systematically analyzed. In this study, we performed a series of experiments on four datasets which consist of 73-125 lava sites with 6-7 samples per lava. The datasets are from different regions and ages, and are large enough to represent paleosecular variation, yet contain demonstrably unreliable datapoints. We show that data filters based on within-site scatter (a k-cutoff, a minimum number of samples per site, and eliminating the farthest outliers per site) cannot objectively identify unreliable directions. We find instead that excluding unreliable directions relies on the subjective interpretation of the expert, highlighting the importance of making all data available following the FAIR principles. In addition, data filters that eliminate datapoints even have an adverse effect: the accuracy as well as the precision of paleopoles decreases with the decreasing number of data. Between-site scatter far outweighs within-site scatter, and when collecting paleomagnetic poles, the extra efforts put into collecting multiple samples per site are more effectively spent on collecting more single-sample sites.