Export 2 results:
Sort by: Author [ Title  (Asc)] Type Year
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z   [Show ALL]
Tauxe, L, Watson GS.  1994.  The Fold Test - an Eigen Analysis Approach. Earth and Planetary Science Letters. 122:331-341.   10.1016/0012-821x(94)90006-x   AbstractWebsite

We combine eigen analysis and parameter estimation techniques for a newly constituted, more versatile fold test. The method is automatic, requiring no assumptions about the polarity or distribution of data, and gives confidence limits on the degree of unfolding required to produce the tightest grouping of data. We illustrate the method using several published data sets that show the tightest data groupings before, after and during correction for bedding tilt. The latter case is usually ascribed to acquisition of remanence during folding, but we show that this behavior can also arise from undetected multiple rotations. In our simulation, the beds undergo rotation about a vertical axis as well as a horizontal one, a case likely to occur in nature. These data, when rotated back to horizontal around what would be the observed strike, exhibit a peak in concentration at about 60% unfolding, very like the behavior of many published data sets. Thus, the origin of remanence in many such cases may not be syn-folding at all, but the behavior may purely be the result of an artifact of structural complications.

Shaar, R, Tauxe L.  2013.  Thellier GUI: An integrated tool for analyzing paleointensity data from Thellier-type experiments. Geochemistry Geophysics Geosystems. 14:677-692.   10.1002/ggge.20062   AbstractWebsite

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.