The Ligurian Alps segment: a short review

The Ligurian Alps are composed of several tectonic units, firstly thiust and piled towards the foreland, then backfolded, and finally involved in Apenninic age and dircetion deformations. They include rock sequences derived from the palco-European continent (from outer io inner domains: Dauphinois; Sub-Brianconnais), from its margin s.s. (Prepieniont s.l.) and from the Piemont-Ligurian ocean. In the Brianconnais domain, the pre-Namurian polymetamorphie basement is covered by a Perum-Carboniferous legument composed of volcanites interbedded with continental deposit, The Meso-Cenozoic sequence follows upwards; it begins witb uppermost Permian-Lower Triassie clastic sediments, covered by mainly Middle Triassie platform carbonates. A variable ('Triassic-Jurassic) time-span gap corresponds to different amounts of crosion and non-deposition, and is in turn followed by Upper Jurassic-Paleocene basinal facies, and finally by Eocene turbidites. In the Prepiemont units, which generally lack pre-Triassie rocks, the Mesozoic sequence is typical of a passive continental margin. The Pieniont-Ligurian domain contains portions of oceanic lithospliere ending with Cretaceotis caleschists. It is higlily probable that the main part of the Upper Cretaccous-Tertiary Helmintoid Flysch was deposited in the same domain. The main tectono-metamorphie Alpine phases in the different units, their temporal correlations and a supposed sequence of geodynamic events are shown in Fig. 5.