Ricostruzione geologica tridimensionale della stratigrafia tardo-quaternaria nel sottosuolo di Ferrara

This work is aimed at the reconstruction of the upper Quaternary depositional architecture, below the urban area of Ferrara, in northern Italy. The study area is part of the lower alluvial plain of the Po and Reno rivers and is therefore dominate by fluvial channel sands, levee sands-silts, and interchannel depression mud. The research was focused on the reconstruction of a digital geological model of the sedimentary bodies buried in the first 35 m under the topographic surface. The study units accumulated through Holocene and late Pleistocene times. The research work is based on the analysis of a rich data set, derived from about 2,000 subsurface investigations, consisting of continuous coring, penetration tests (including CPTU and SCPTU), and water wells stratigraphy. The subsurface modelling was achieved through both the conceptual interpretation of surface and subsurface information and the computerized geostatistic interpolation of digitalized data. The digital interpolation overcame the large heterogeneity of the data set into a homogeneous statistical and conceptual framework, through the use of a time and economic efficient work protocol. The research work achieved the reconstruction of the environmental evolution of the area, from the last glacial maximum time up to the present. The large climatic and eustatic fluctuations of the Quaternary largely influenced the environmental evolution and sedimentary dynamics of the area. During the last sea-level lowstand, a large body of synglacial river sands accumulated into the research area, under middle alluvial plain conditions. During phases of the eustatic rising, a thick alluvial plain body aggraded in the southern portion of the study area, fed by Apennines derived rivers, whereas non depositional condition persisted on the northern structural high. The maximum transgression was matched with the widespread sedimentation of fresh water marsh muds. During the highstand times, sands accumulated into both the Po and Reno channels, and mud into the adjacent interfluvial depressions. The research work demonstrated the great role played by the compressive deformation of this portion of the seismic active Apennines Foredeep Basin in the shaping of the depositional architecture. The sedimentary successions accumulated onto the anticline crests are much thinner than those sedimented into the syncline areas. The stratigraphic interpretation of the subsurface data can improve the geotechnical and hydrogeological work and support an improved seismic danger mitigation of an area significantly affected by the May 2012 earthquakes.