strati.ch - Lexique lithostratigraphique de la Suisse

Représentation et statut

Variantes historiques: Monte Olimpino Backthrust (TK500 / Gouffon et al. 2024)

Termes génériques

Type de protolithe

Révision: Gouffon Yves (Editor) (2024) : Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern

p.104: The Oligocene–Miocene Gonfolite Lombarda Group represents a deep-water clastic wedge deposited during the post-collisional growth of the South Alpine fold-and-thrust belt. In the area south of Como–Chiasso–Varese, these late synorogenic sediments, belonging to the Milan Belt, are thrust to the north over the Lower Orobic Imbricates along the Monte Olimpino Backthrust during the latest phases of deformation of the latter unit (Bernoulli et al. 1989). Unconformities within the Gonfolite Lombarda Group and reworking of older sediments indicate that the Neogene South Alpine thrust-and-fold belt grew during deposition of the Gonfolite Lombarda Group (Bernoull i et al. 2018). Apatite fission tracks are completely or partially annealed in detrital apatites in Oligocene sediments, whereas the Miocene sediments show no annealing of the apatite fission tracks (Wagner 1988, Giger 1991, Bernoull i et al. 1993), indicating that the lower part of the Gonfolite Lombarda has been exhumed along the Monte Olimpino Backthrust from a depth of more than 3 km. Sediments as young as Serravallian are involved in folding and thrusting at the foothills of this region (Tremolada et al. 2010).