The Birth of the Western and Central Alps: Subduction, Obduction, Collision

Publisher Summary This chapter discusses the birth of the Western and Central Alps. The Alpine orogeny was initiated by the northward convergence of Apulia–Africa with respect to Eurasia. The orogenesis followed a succession of characteristic stages—subduction, obduction, collision, and hypercollision with back-thrusting that led to the construction of the orogenic wedge. The Central Alps are represented by the Matterhorn transect. The Pre-alpine nappes along this transect have escaped subduction and most of the metamorphism and thus provide precise chronological indicators lost in the internal zones because of their intense deformation. The onset of subduction is indirectly dated by the Late Cretaceous age of early flysch deposition. The start of convergence at the end of the Late Cretaceous is poorly calibrated chronologically. The Eocene paroxysmal construction of the collisional wedge ended with the succeeding hypercollision in the Late Oligocene. One of the singularities of Western Alps structure results from lateral ramp in the Alpine fold belt.