Geolectrical and GPR joint prospection in Palo Blanco archaelogical site

MARTINO, LUIS; LASCANO, EUGENIA; BONOMO, NÉSTOR; OSELLA, ANA; RATTO, NORMA

Palermo, ItalyRome, Italy

Congreso; 6th International Conference on Archaeological Prospection; 2005

Geophysical surveys provide important information to the archaeological community for the exploration and characterization of archaeological underground sites, in particular for the detection and localization of anthropological structures. The GPR and the geoelectrical methods have been applied to investigations as pre-excavation techniques for many years (Herbich et al., 1997; Pipam et al., 2001). These methods are particularly suitable for this type of surveys since they posses high lateral resolution for shallow depths of study.In this work we present a geophysical prospection in Palo Blanco archaeological site, located in Fiambalá valley, Catamarca province, N-W Argentina. This is a semi-desert area, with a predominantly sandy composition of the soil, with a smaller portion of clays. The archaeological site was discovered in 1950 and it consists in five buildings, covering an area of around 300 m2. The GPR and the geoelectrical methods were applied to obtain a detailed map of one of these buildings. The accurate localization of the buried structures was necessary to design a more precise excavation plan to preserve this ancient archaeological place. The electrical profiles were acquired using the multielectrode resistivimeter Saris 500. We deployed dipole-dipole arrays with apertures of 1 m. As stated previously, the objective of this survey was to obtain a detailed map of the archaeological structure of interest to delineate and characterize its fine features. In order to achieve this goal, 20 profiles with an individual extension of 24 metres in the south-north (S-N) direction and 9 profiles of 24 metres in the west-east (W-E) directions were made; a total of 29 lines covering an approximately 600 m2 area were done. Data were inverted applying the DCIP2D inversion code (2001) developed by the University of British Columbia (UBC) and based on the work of Oldenburg et al. (1993) and Oldenburg and Li (1994). Topographic corrections were made when necessary. For the implementation of the GPR an antenna of 400 MHz was used to achieve good shallow vertical resolution. The equipment used in this work was a portable monostatic/MONOCANAL IDS. 40 scans per meter were taken in every profile. The lines were carried out covering the same sector of the electrical profiles, with a 1 m ´ 1 m.