The role of structural inheritance in continental break-up and
exhumation of Alpine Tethyan mantle (Canavese Zone, Western Alps)
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Abstract
The Canavese Zone (CZ) in the Western Alps represents the remnant of the distal passive margin of the
Adria microplate, which was stretched and thinned during the Jurassic opening of the Alpine Tethys.
Through detailed geological mapping, stratigraphic and structural analyses, we document that the continental
break-up of Pangea and tectonic dismemberment of the Adria distal margin, up to mantle rocks
exhumation and oceanization, did not simply result from the syn-rift Jurassic extension but was strongly
favored by older structural inheritances (the Proto-Canavese Shear Zone), which controlled earlier lithospheric
weakness. Our findings allowed to redefine in detail (i) the tectono-stratigraphic setting of the
Variscan metamorphic basement and the Late Carboniferous to Early Cretaceous CZ succession, (ii) the role
played by inherited Late Carboniferous to Early Triassic structures and (iii) the significance of the CZ in the
geodynamic evolution of the Alpine Tethys. The large amount of extensional displacement and crustal
thinning occurred during different pulses of Late CarboniferouseEarly Triassic strike-slip tectonics is wellconsistent
with the role played by long-lived regional-scale wrench faults (e.g., the East-Variscan Shear
Zone), suggesting a re-discussion of models of mantle exhumation driven by low-angle detachment faults
as unique efficient mechanism in stretching and thinning continental crust.
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