Thellier GUI: An integrated tool for analyzing paleointensity data from Thellier‐type experiments

Abstract

[1] Thellier-type experiments are a method used to estimate the intensity of the ancient geomagnetic field from samples carrying thermoremanent magnetization. The analysis of Thellier-type experimental data is conventionally done by manually interpreting data from each specimen individually. The main limitations of this approach are: (1) manual interpretation is highly subjective and can be biased by misleading concepts, (2) the procedure is time consuming, and (3) unless the measurement data are published, the final results cannot be reproduced by readers. These issues compound when trying to combine together paleointensity data from a collection of studies. Here, we address these problems by introducing the Thellier GUI: a comprehensive tool for interpreting Thellier-type experimental data. The tool presents a graphical user interface, which allows manual interpretation of the data, but also includes two new interpretation tools: (1) Thellier Auto Interpreter: an automatic interpretation procedure based on a given set of experimental requirements, and 2) Consistency Test: a self-test for the consistency of the results assuming groups of samples that should have the same paleointensity values. We apply the new tools to data from two case studies. These demonstrate that interpretation of non-ideal Arai plots is nonunique and different selection criteria can lead to significantly different conclusions. Hence, we recommend adopting the automatic interpretation approach, as it allows a more objective interpretation, which can be easily repeated or revised by others. When the analysis is combined with a Consistency Test, the credibility of the interpretations is enhanced. We also make the case that published paleointensity studies should include the measurement data (as supplementary files or as a contributions to the MagIC database) so that results based on a particular data set can be reproduced and assessed by others.Components: 8,900 words, 10 figures.

Archaeointensity results spanning the past 6 kiloyears from eastern China and implications for extreme behaviors of the geomagnetic field

“…S1-S3; Rock Magnetic Results) indicate thermally stable fine-grained magnetite and titanium (Ti)-and/or aluminum (Al)-substituted magnetite as the dominant magnetic carriers for most samples, which suggest the suitability of these samples for paleointensity experiments. To obtain the most robust paleointensity data, we need to select the results based on a series of criteria [Paterson et al (18)], for example, those suggested by Shaar and Tauxe (19). The selection…”

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

“…The accepted samples (91 in total) are listed in Table 2 and the specimen level results are listed in Table S3. Data are analyzed with PmagPy software by Lisa Tauxe including the Thellier GUI program by Shaar and Tauxe (2013). The anisotropy of the studied specimens is not so strong as expected for archaeomagnetic materials, with τ 1 /τ 3 varying between 1.02 ∼ 1.85 (97% of them less than 1.5), where τ 1 and τ 3 are the maximum and minimum eigenvalues of the ATRM tensors respectively .…”

Full vector magnetic dating of some pyroclastic rocks associated to the Colima volcano, western Mexico

“…These specimens exhibited almost linear behavior in both the Arai and associated Zijderveld plots while the control heatings were also positive (within the 10 %). Small secondary viscous components may be present but easily removed at first temperature stages, between 250° C and 300° C. The quality parameters (Coe et al, 1978) match the commonly adopted criteria and the SCAT parameter was accomplished (Shaar and Tauxe, 2013). All analyzed samples show reliable absolute intensity determinations (Table 1B).…”