The Geology of Monte Tignoso and Pian Dei Cavalli area (Val San Giacomo, Central Alps, Italy): a field trip along the tectonic boundary between the Tambo and Suretta Nappes

DOI: https://doi.org/10.3301/GFT.2025.04 - Pages: 1-42

¹Dipartimento di Scienze della Terra 'Ardito Desio' - Università di Milano - Italy.

Corresponding e-mail address: francesco.arrigoni@unimi.it

The Monte Tignoso area, located along the western flank of Val San Giacomo (Central Alps), offers a unique and well-exposed crosssection through the tectonic contact of the Middle Penninic Tambo and Suretta nappes, as a result of the tectonic coupling during the final stages of the continental collision between the European and Adriatic plates. The Permian-Mesozoic meta-sedimentary pile of the Tambo nappe is mainly made up of quartzites and successions of metacarbonates, and it is pinched between the poly-metamorphic basement rocks of the Tambo and Suretta nappes. The one-day round trip illustrates a geological transect through the nappe stack, starting from the upper portions of the Tambo nappe basement, crossing the meta-sedimentary cover, up to the Suretta nappe basement, which forms a tectonic klippe on the top of Monte Tignoso. Furthermore, the field trip shows the main geomorphological and Quaternary peculiarities encountered along the way, as periglacial landforms, deep slope gravitative deformations and a well-developed karst system, all controlled, at least partially, by the distinctive geological and structural features that characterise the area. The peculiar setting of the area, combined with a non-harsh environment, makes it suitable for an easy one-day field trip capable of condensing multiple geological evidence typical of the Central Alps.

Central Alps, Tambo nappe, Suretta nappe, structural geology, Quaternary geology.