3. Methodology

Each sampled site consists at least of 4–5 hand samples or 6–7 cores obtained by portable drilling and orientated by magnetic (Brunton) and sun compass (Azimut 0–360 and dip 0–90).

Kappabridge MFK-1A and KLY-2 (by Geofyzika Brno) were utilized to measure the AMS directions, at the Paleomagnetism Laboratory "Daniel A. Valencio" (IGEBA) of the Geologic Sciences Department of the Buenos Aires University (UBA) and at Colgate University, respectively. Previously to measure, it is necessary to ingress the field sample orientation because the AMS direction results are in specimen coordinates (without field correction) and in geographic coordinate (with field correction). The results were analyzed with the program Anisoft 4.2 (provided by Geofyzika Brno) to obtain directional results of AMS scalar axes represented in the ellipsoids and their statistic parameters, in situ and with structure correction, and the AMS degree (P) and the shape parameter (T) values. It is possible to make automatically the structure correction with the program, taking the bedding planes to the horizontal. The T and P parameter values were plotted in the diagram of Jelinek [51].

The AMS data obtained, were integrated with paleomagnetic and field structural data of each locality, to improve the interpretations.
