Abstract:

In the region of the deltaic field of Pinios River in Thessaly and under an applied geoenvironmental research, a preliminary geophysical survey was developed. In this direction, an attempt was made to develop a grid of positions-measurements that would be able to cover the whole field in order to adumbrate the general “image” of the geoelectric parameters. From the conducted bibliographic research, it seems that it is the first time that such a coordinated and extensive geophysical survey has been made in the area. In this project and in the direction of the evaluation of the geoelectric parameters of lithology present in the deltaic area, displays of the horizontal and vertical distribution of electrical resistivity are presented. This knowledge will contribute to the emergence of new data and information on the subsurface structure of the field of the deltaic plain. The geoelectrical method with the Sclumberger array was applied, for the vertical investigation of the distribution of electrical resistivity, in order to investigate the geoelectrical parameters. These arrays are best suited, as a preliminary subsurface investigation method in such geo-environments. Thirty seven soundings were developed in an almost 'normalized' grid, aiming to the greatest possible depth of investigation. Towards this direction, despite the very difficult condition of accessibility, the development of the electrode current (AB or C1C2) reached 1.100 meters, with an investigation depth >250 meters. From the sections and the constructed maps, conductive geoelectric distributions structures detected, with a resistivity ranging in 5-30 Ohm.m, in almost the whole subsurface field of deltaic plain. From this general view, seems to differentiate the coastal zone for shallow depths (<4.5 m) of investigation, the regions of the southern part of the deltaic plain with larger resistivity values for large depths (> 100 m) and the western region (Pyrgetos), with generally high values even from the shallow depths of investigation. Finally, the overall picture of the distribution of the geoelectric parameters in the field of study appears to outline potential area of the palaeogeographic development of the Pinios River delta.

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