The role of structural inheritance in continental break-up and exhumation of Alpine Tethyan mantle (Canavese Zone, Western Alps).

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 Carboniferous–Early Triassic strike-slip tectonics is well-consistent 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. Image 1 • Paleozoic structural inheritance controlled Pangea break-up and opening of Jurassic Alpine Tethys and mantle exhumation. • Crustal thinning already occurred during different pulses of Late Paleozoic wrench tectonics. • Significant implications for processes of oceanic basins formation and geodynamic of oceanic metamorphic orogenic belts. • Structural inheritances should be take in consideration in processes of mantle exhumation and opening of oceanic basins. [ABSTRACT FROM AUTHOR]