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Unbiased analysis of geomagnetic data sets and comparison of historical data with paleomagnetic and archeomagnetic records
Author(s) -
Arneitz Patrick,
Egli Ramon,
Leonhardt Roman
Publication year - 2017
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1002/2016rg000527
Subject(s) - earth's magnetic field , paleomagnetism , weighting , geology , lava , geophysics , field (mathematics) , secular variation , volcano , geodesy , paleontology , magnetic field , physics , mathematics , quantum mechanics , acoustics , pure mathematics
Reconstructions of the past geomagnetic field provide fundamental constraints for understanding the dynamics of the Earth's interior, as well as serving as basis for magnetostratigraphic and archeomagnetic dating tools. Such reconstructions, when extending over epochs that precede the advent of instrumental measurements, rely exclusively on magnetic records from archeological artifacts, and, further in the past, from rocks and sediments. The most critical component of such indirect records is field intensity because of possible biases introduced by material properties and by laboratory protocols, which do not reproduce exactly the original field recording conditions. Large biases are usually avoided by the use of appropriate checking procedures; however, smaller ones can remain undetected in individual studies and might significantly affect field reconstructions. We introduce a new general approach for analyzing geomagnetic databases in order to investigate the reliability of indirect records. This approach is based on the comparison of historical records with archeomagnetic and volcanic data, considering temporal and spatial mismatches with adequate weighting functions and error estimation. A good overall agreement is found between indirect records and historical measurements, while for several subsets systematic bias is detected (e.g., inclination shallowing of lava records). We also demonstrate that simple approaches to analyzing highly inhomogeneous and internally correlated paleomagnetic data sets can lead to incorrect conclusions about the efficiency of quality checks and corrections. Consistent criteria for selecting and weighting data are presented in this review and can be used to improve current geomagnetic field modeling techniques.