EarthRef.org Digital Archive (ERDA) -- A Matlab tool for archaeomagnetic dating

Description
A Matlab tool for archaeomagnetic dating has been developed in this work. Well-dated palaeosecular variation curves (PSVCs) can be used to date archaeological artefacts with unknown ages. The archaeomagnetic direction (declination and/or inclination) and the archaeointensity obtained from the archaeological artefact are compared with a master PSVC. In addition, historical lava flows with controversial ages can be dated using this methodology. The dating process follows the descriptions given by Lanos (2004), which is based on the combination of temporal probability density functions of the three geomagnetic field elements. Here, we develop an interactive tool in Matlab code to carry out archaeomagnetic dating by comparing the undated archaeomagnetic (or lava flow) data with a master PSVC. The master PSVCs included with the Matlab tool are the different European curves and those generated using both regional and global geomagnetic field models. A case study using all the PSVCs available in Europe and some undated archaeomagnetic data has been carried out to analyze how the different PSVCs affect the dating process. In addition, the dating uncertainty and the relocation error have been analyzed in the European region. Results show that some regional PSVCs and the regional SCHA.DIF.4k archaeomagnetic model are the best choices to obtain an accurate date in Europe. Moreover, when it is available, the full geomagnetic field vector must be used for archaeomagnetic dating.

Instructions
After downloading the compressed file archaeo_dating.rar, the decompressed folder must be put into the Matlab working folder: work (usually in C:\Matlab\RXXX\work).

To run the Matlab tool, write in the Command Window of Matlab:

>>archaeo_dating

and an interactive window will appear. Three different colour areas are shown in the interactive window. Red area should contain the archaeomagnetic information to the site to be dated. It is divided into two parts: (i) the directional and intensity values with their respective uncertainties (declination, inclination, a95, intensity and sF) and (ii) the location information (the latitude, the longitude and the name of the archaeological sample). The user can choose the archaeomagnetic elements to be used, and set their values. If an element is not available, as it can be the case of the intensity, the user must not select that element.

The master PSVC used for dating is selected in the blue area. Four buttons show the different sources of the PSVCs:

(i) The available European PSVCs.

(ii) The global models SHAWQ (Campuzano et al., 2019; Osete et al., 2020); SHA.DIF.14k (PavÃ³n-Carrasco et al., 2014); ARCH3k.1 (Korte et al., 2009); CALS3k.4 (Korte and Constable, 2011); and CALS10k.1b (Korte et al., 2011).

(iii) The European regional models SCHA.DIF.8k and SCHA.DIF.4k (PavÃ³n-Carrasco et al., 2010, 2021) and the regional model for Africa SCHAFRICA.DIF.4k (Di Chiara and PavÃ³n-Carrasco, 2022).

(iv) A last button gives the possibility to include a new master PSVC by the user. After pressing a button, a new window will appear to select the different PSVCs or models described in the previous section. If the user uses a new PSVC (not included into the Matlab tool) the software asks for the new file. When a Bayesian PSVC is selected, it is transferred from the reference location to the site location. This does not occur for the PSVCs given by the regional and global models, because they are calculated at the site location.

After including the archeomagnetic information and the master PSVC, the user can define the time interval used for dating and the statistical probability estimation. These parameters are into the green area. Finally, the button Dating must be pressed to obtain the results.