Analyses of the Distribution and Nature of the Natural Cementation of Quaternary Sediments: The Case of the Turin Subsoil (Italy)

The finding of a remarkable number of stratigraphies from mechanical surveys and water research wells, drilled in the urban area of Turin over the last few decades, has made it possible to reconstruct the geology of the subsoil in great detail. In particular, it has been possible to define the distribution of the cementation in the Quaternary alluvial sediments through geological planimetries that refer to different depths from the ground level. The cementation map of the Turin subsoil can be considered very useful for the planning of future underground works and for the definition of the necessary construction methods. An accurate mineralogical analysis has identified a “meniscus” type structure of the cementation; this leads us to believe that the cementation has formed in a vadose environment. The reason for the precipitation of the calcium carbonates is therefore probably due to infiltration of the slightly acidic meteoric water into the subsoil and not to the mixing of water with different temperatures, hardness and pH values, as some authors believed in the past.