A complementary, two-method spherical approach to direction-based archeomagnetic dating.

We present a two-method spherical approach to archeomagnetic dating based on directional variations of the geomagnetic field after vector treatment of all data, including individual in situ structure-level data used to calculate the reference variation curve and the archeomagnetic direction to be dated. In this paper, the reference curve for France was determined from a compilation of data acquired from kiln structures using a sliding window technique in which the varying durations and time shifts between windows are fixed according to the temporal distribution of individual reference data, as well as the bivariate extension of Fisher's statistics. The first dating method involves identifying the time interval(s) in which the direction to be dated is closest to the mean directions that define the reference curve. The angles between the direction to be dated and reference curve directions, and the Fisher probability density function allow us to derive a coincidence probability density curve, from which it is possible to estimate a 95% probability level-based dating interval. The second dating method involves the determination of an archeomagnetic date in which the direction to be dated is statistically identical to a dated reference curve direction at the 95% confidence level. This approach is much more restrictive than the previous method because it requires an excellent agreement between the test and reference directions to obtain a dating result, while the first method is only based on relative proximity. Using examples of archeomagnetic dating, we show that these two methods are complementarity and should be applied jointly to account for some of the limitations inherent in archeomagnetic dating, particularly due to the dispersion of the reference structure-level data. • We use a vector treatment of archeomagnetic directions for dating purposes. • A dating method involving the maximum proximity to a reference curve was developed. • A method involving the statistical compatibility to a reference curve is also used. • Both dating methods are applied to French archeomagnetic direction data. • We show the effectiveness of the joint use of these two archeomagnetic dating methods. [ABSTRACT FROM AUTHOR]