Paleogeography
The Sesia zone is, like the rest of the Austroalpine nappes, considered to have been a northern piece of the microcontinent Apulia or a semi-independent microcontinent that was situated just north of Apulia. When the continents Europe and Africa were divided by a rift zone in the Jurassic period, Apulia and the Austroalpine are supposed to have rifted apart from Africa (just like for example the present day British Isles, which are separated from the rest of Europe by the North Sea basin). When the plates converged again in the Paleogene, many small pieces of continental crust, like the Austroalpine microcontinent, became incorporated in the nappe stacks of the Alps.
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