Geological map of the External Ligurian Units in western Monferrato (Tertiary Piedmont Basin, NW Italy)

A detailed geological map of the External Ligurian Units in western Monferrato, Italy, reveals a complex tectono-stratigraphic setting shaped by four distinct tectonic stages. Contrary to previous descriptions of these units as an undifferentiated chaotic complex, this 1:10,000-scale map identifies a Late Cretaceous succession comprising the Argille varicolori and the overlying Monte Cassio Flysch, sealed by late Eocene deposits from the Tertiary Piedmont Basin. Crosscutting relationships between stratigraphic unconformities and faults highlight significant geological processes, including layer-parallel extension during the Late Cretaceous–early Eocene, drowning of shelf sediments controlled by NW-striking left-lateral transtensive faulting in the Oligocene, and gravitational emplacement of late Oligocene breccias. The study also identifies NW-striking right-lateral transpressive faults that cut through earlier structures, sealed by a Tortonian unconformity.

Festa, A., & Codegone, G. (2013). Geological map of the External Ligurian Units in western Monferrato (Tertiary Piedmont Basin, NW Italy). Journal of Maps, 9(1), 84–97. https://doi.org/10.1080/17445647.2012.757711