Abstract:

In this project the geological subsurface structure of the delta of the river Pinios is investigated through the contribution of geophysical soundings. In order to investigate the lithologic structure of the entire deltaic field, geophysical soundings were performed with the geoelectrical method of vertical investigation of the resistivity distribution at 37 locations. The Schlumberger array was applied, which is a reliable preliminary geophysical technique for such environments, achieving an investigation depth of > 200-250 meters. Obtaining information on the geoelectrical characteristics of the formations expected under the alluvial silt of Pinios, we have to evaluate the results of the geophysical survey. Therefore 14 “in situ” measurements of electrical resistivity were carried out in surface outcrops of Neogene sediments, cyanoschists and serpentinites. An extensive geological overview of the wider visual field was conducted, geological measurements were recorded and plotted on a digital background concerning the extensive volume of Neogene formations and alpine formations. After the processing of the geophysical soundings, geoelectrical sections were constructed in directions S-N and W-E, along with the description of their geological evaluation. From the preliminary results, it seems that the Neogene formations, with alternations of sands, marls and conglomerates occupying almost the entire space of the subsurface deltaic field, below the Holocene deposits. The alpine formations of Ossa (the southern part of the field research), seem only to be traced in the soundings near the margins, with a gentle inclination below from the post-alpine sediments and for the depths investigated (~ 200-250 meters). In the western part of the study area and more specifically the Pyrgetos sub basin, higher values of electrical resistivity (50-80 ohm) were calculated, differentiating the general concept that emerges from the rest of the study area.

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