Elements of particular interest

Considering the northern Pontine islands’ geographical position, lying on the edge between the continental platform of central Italy and the eastern border of the Tyrrhenian basin, this Sheet is particularly relevant in studying the geological and structural relations between the sectors concerned. Its realization also involved experimenting new mapping methods, such as the application of “New Guidelines for the mapping of marine areas on a scale of 1:50,000". The Guidelines were published on this site and prepared by the Geological Service of Italy in conjunction with a team of Mapping Directors for sea areas falling within CARG sheets. Preparing the Sheet also involved the adoption of UBSUs on volcanic islands.

Mapping of the emerged part of the archipelago also proved to be particularly useful and important. It not only provided the adoption of an innovative stratigraphic method (which involved mixing UBSUs and lithostratigraphy) but its results, matched with the previous ones obtained in the coastal areas of northern Lazio, enabled the identification, reinterpretation and correlation of some regional sea abrasion surfaces. Furthermore, the new stratigraphic arrangement enabled a different reconstruction of volcanic events with respect to ones proposed so far. It was also essential for solving the archipelago’s geological evolution, by reviewing the geometrical land relations between the volcanic and sedimentary units (which outcrop in Zannone). All this also provided an important contribution in evaluating the extent of regional lifting during the volcanic stages of the Tyrrhenian margin.

The platform area surrounding the islands is of particular interest since it is characterized by the existence of current and subcurrent deposit systems having a prevailingly carbonatic sedimentation. These are very different from the ones on the Lazio margin, and the Italian margins in general, which are dominated by silico-clastic sedimentation. Therefore, even from a geological mapping point of view the area is a limit case, compared to conditions that are normally found. The survey and interpretation methods (according to stratigraphic and sequential criteria) are also different. Studies realized for the preparation of the Sheet provided important spin-offs for research. The multidisciplinary and integrated approach provided new data on carbonatic sedimentation in temperate areas. This was matched to data on land deposits, mainly based on direct sampling and the seabed’s morphological analysis. The realization of this Sheet also enabled the experimentation of marine element digitization procedures. This stage completed the preparation of new guidelines for marine areas.

Finally, the dry land part (with partial sedimentary filling of ancient lagoon systems in the area behind the dunes) shows that the area’s evolution is related to sea level variations mainly due to climatic phenomena. Today, this area is morphologically regularized by reclamation activities.