Structural anatomy of the Ligurian accretionary wedge (Monferrato, NW Italy), and evolution of superposed melanges

Research reveals the complex, multi-stage evolution of the Ligurian accretionary wedge in northwestern Italy, highlighting three sequentially formed mélanges—tectonic, diapiric, and sedimentary—that developed through Late Cretaceous to late Oligocene processes. The study identifies a structurally ordered block-in-matrix fabric from tectonic mélange, triggered by NE-vergent thrusting during continental collision, while overpressurized fluids along thrust faults drove the rise of shaly material, forming diapiric mélange and later sedimentary mélange units. This interplay of tectonic, diapiric, and sedimentary processes controlled the dynamic equilibrium of the accretionary wedge, suggesting similar polygenetic mélanges may contribute to tsunamic events in convergent margins. The findings are based on multiscale structural analysis, offering insights into the geodynamic evolution of the NW Apennines–western Alps.

Festa, A., Dilek, Y., Codegone, G., Cavagna, S., & Pini, G. A. (2013). Structural anatomy of the Ligurian accretionary wedge (Monferrato, NW Italy), and evolution of superposed melanges. Geological Society of America Bulletin, 125(9-10), 1580–1598. https://doi.org/10.1130/b30847.1