Tectonic Evolution of the Tambò nappe in the Central Alps: A Petrochronological Study

• Applicants: Dr. Axel Gerdes; Professorin Dr. Lucie Tajcmanova
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566280178

The crystalline nappes of the Central Alps, particularly the Adula, Tambò, and Suretta nappes in the eastern Penninic Domain, have provided significant insights into the orogenic processes that shaped this region. These nappes, notable for recording both the ancient Variscan and younger Alpine orogenic phases, are currently being reexamined through fieldwork associated with the Italy's national 1:50,000 geological mapping campaign in the Valchiavenna area. This research has uncovered several high-temperature (HT) geological features in the Tambò nappe that suggest its formation in an extensional regime post-Variscan orogeny, a hypothesis not yet fully explored. The project aims to reconstruct the geological evolution of the Tambò nappe by integrating new field observations with detailed petrochronological data. It will employ phase equilibria modeling and U-Pb dating of garnet and zircon to establish the Pressure-Temperature-time (P-T-t) paths. This approach, involving LA-ICP-MS techniques in collaboration with the University of Frankfurt, will compare new findings with traditional methods to enhance the understanding of the nappe's complex history. If the hypothesis is confirmed, this study will provide the first evidence of post-Variscan HT conditions within the Penninic Domain of the Central Alps, contributing to a broader understanding of the region's geodynamic evolution. Moreover, a data-supported restoration of the pre-Alpine tectonic setting of the Tambò nappe coupled with the detailed definition of its Alpine metamorphic evolution will provide insights into the role of pre-orogenic thinned terrains during later subduction and collision processes.

• DFG Programme: Research Grants
• International Connection: Italy, Switzerland
• Cooperation Partners: Dr. Filippo Schenker; Professorin Paola Tartarotti