Archean craton assembly and Paleoproterozoic accretion-collision tectonics in the Reguibat Shield, West African Craton

Interpretation of the deformation pattern of the western Reguibat Shield by integrating current geochronological knowledge allows deciphering the assembly and post-assembly tectonic history of the Awsard craton that became involved in the giant Eburnean (∼2 Ga) accretionary orogen. Final craton assembly took place along the newly recognized early Siderian (2.51–2.46 Ga) Tiris orogen. The eastern margin of the craton was then affected until 2.07–2.03 Ga by a west-verging (i.e., craton-ward) thrust system rooted in the collisional contact with the Eburnean orogen. Collision was controlled by thermal erosion and softening of the craton edge by the accretionary orogen, which allowed for the propagation of the thrust system during craton-ward progression of delamination of the cratonic lithospheric mantle. This resulted in the progressive incorporation of Archean crust into the accretionary orogen. Such a hot mode of collision provides a mechanism for the destruction of cratons by reworking of their crust into their flanking accretionary orogens and recycling of their lithospheric mantle into the asthenosphere. The hot collision mode favors the formation of specific oroclines driven by lithospheric mantle delamination.