Piemont-Liguria Ocean

[1] The Piemont-Liguria Ocean was formed in the Jurassic period, when the paleocontinents Laurasia (to the north, with Europe) and Gondwana (to the south, with Africa) started to move away from each other.

When the Apulian plate started moving to the northwest in the late Cretaceous, Piemont-Ligurian crust began to subduct beneath it.

In the Paleocene the Piemont-Ligurian Ocean had completely disappeared under the Apulian plate and continental collision started between Apulia and Europe, which would lead to the formation of the Alps and the Apennines in the Tertiary.

These nappes were subducted, sometimes to great depths in the mantle, before being obducted again.

Due to the high pressures at these depths, much of the material had been metamorphosed in the blueschist or eclogite facies.