Testing paleomagnetic directional distributions against field models for
the averaging of secular variation and correcting for inclination
shallowing using an updated elongation/inclination approach (SVEI)
Abstract
This paper addresses one of the critical questions of scientific
inquiry: How do we know when a given data set is representative of the
phenomenon being examined? For paleomagnetists, the question is often
whether a particular dataset sufficiently averaged paleosecular
variation (PSV). To this aim, we updated an existing PSV dataset that
now comprises 2441 site mean directions from 94 individual studies
(PSV10-24). Minimal filtering for data quality resulted in 1619 sites
from 90 publications. Fitting PSV10-24 with three newly defined
parameters as well as two existing ones form the basis of a Giant
Gaussian Process field model (THG24) consistent with the data. Drawing
directions from THG24 yields directional distributions predicted for a
given latitude allowing a comparison between empirical distributions and
the cumulative distribution function generated by the model. This tests
whether the observed data adequately averaged out PSV according to
THG24. Sedimentary datasets that may have experienced inclination
shallowing can be corrected using an (un)flattening factor that yields
directions satisfying THG24 in a newly-defined, four-parameter space.
This approach builds on the Elongation-Inclination (E/I) method of Tauxe
and Kent (2004), so the approach introduced here is called SVEI. We show
examples of the use of SVEI and explain how to use this newly developed
python code that is publicly available in the PmagPy GitHub repository.