(Ultra-) High-pressure metamorphism and orogenesis: An Alpine perspective

摘要: Abstract The Pressure–Temperature–time–deformation evolution of the high- to ultra-high-pressure units Western Alps has been progressively refined in last 40 years, leading several paradigm shifts understanding orogenesis. This set information, combined with Cretaceous–Tertiary plate kinematic reconstructions and Mesozoic palaeogeography, indicates that represent amalgamation a Cretaceous an Eocene orogen, which developed at expense Adriatic European rifted margins, respectively. In Cretaceous, NNE-directed drift plate, parallel inherited Jurassic structural trends, led development highly oblique subduction boundary. this setting, Canavese Zone parts Sesia Zone, derived from hyper-extended margin, underwent deformation metamorphism conditions ranging sub-greenschist eclogite facies. A Lower switch NNW-directed motion, perpendicular rift-related culminated collision between proto-Alps Brianconnais block ca. 44 Ma. As result, Domain its preserved (U)HP Piemonte Units, were accreted orogen. Continued convergence was subsequently accommodated by more external Valaisan basin thinned margin. arrival thick continental crust zone 35–30 Ma marked onset final collision. To first order, orogen grew through progressive episodic accretion located towards north-westerly positions. Accretion subducting front coeval reworking tectonic contacts hangingwall units, locally resulting renewed deformation/metamorphism.