GEOPHYSICAL INVESTIGATION WITHIN THE ZENNARE BASIN (VENICE)

A multi-technique geophysical investigation is performed to map the shallow depositional units in the Zennare peat basin nearby the Venetian Lagoon. The detection and resolution capabilities of Earth Resistivity Tomography, Refraction Seismic, and Ground Probing Radar are compared in a small test area within the basin, where also additional stratigraphic point information is available. The results obtained with the different methods prove comparable, and the integration of these distinct geophysical responses allows for a more precise identification of the subsurface structure. The Ground Probing Radar survey, because of its cost-effectiveness, has been extended to the entire basin. Some coherent noise patterns, associated with the frozen ground surface, required a specific processing sequence to enhance the radar record quality. The radar images outline the main shallow discontinuities of the basin related to the different depositional framework, allowing for a detailed reconstruction of peat layers as well as of a series of sand-silty paleo-channels distributed within the area. Borehole and remote sensing data are used to calibrate the geophysical interpretation.