Rock magnetic controls on paleointensity data
Abstract
Linking rock magnetic properties to the results of paleointensity experiments has been a long term goal in efforts to improve paleointensity reliability, but no clear relationship has yet been identified. Using hysteresis data from magnetite specimens of known grain size, we derive a measure of a specimen's bulk domain stability (BDS).
Comparing BDS to paleointensity results from Coe-type control experiments we show that BDS is strongly correlated with accuracy of these results and how curved the Arai plots are. A similar analysis using historical paleointensity data, which can be compared to direct observations of the field strength, reveals similar, but weaker correlations between BDS and paleointensity accuracy and Arai plot curvature. This is despite the presence of laboratory alteration, a diversity of experiments (various temperature steps, lab field strengths, and field angles), and specimen heterogeneity (rock magnetic properties were measured on sister specimens), all of which will hinder our ability to identify rock magnetic controls on paleointensity data. Furthermore, BDS has correlations with the results from other paleointensity methods, including the multispecimen protocol and the non-heating pseudo-Thellier method. These analyses indicate that the effective bulk domain stability of a specimen controls the fidelity of its paleointensity data and is a factor in most natural materials. The relationships that we have identified can be used as a means to pre-select specimens that are mostly likely to yield accurate results, to improve data selection criteria, and to retrospectively analyze the reliability of previous published results.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGP21A0635P
- Keywords:
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- 1521 Paleointensity;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1527 Paleomagnetism applied to geologic processes;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1540 Rock and mineral magnetism;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1595 Planetary magnetism: all frequencies and wavelengths;
- GEOMAGNETISM AND PALEOMAGNETISM