Details

Autor(en) / Beteiligte

• Herwegh, M.
• Berger, A.
• Glotzbach, C.
• Wangenheim, C.
• Mock, S.
• Wehrens, P.
• Baumberger, R.
• Egli, D.
• Kissling, E.

Titel

Late stages of continent-continent collision: Timing, kinematic evolution, and exhumation of the Northern rim (Aar Massif) of the Alps

Ist Teil von

• Earth-science reviews, 2020-01, Vol.200, p.102959, Article 102959

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2020

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The Alpine front’s External Crystalline Massifs represent exhumation of mid-crustal basement during late-stage continent-continent collision. We unravel the geodynamic evolution of the Northalpine front (Aar Massif) by combining structural and low-T thermochronometric data. A crustal-scale tectonic restoration (Neogene-present) and estimation of associated changes in exhumation rates become possible. The European continental margin experienced multiple switches from horizontal- to vertical- and again to horizontal-dominated tectonics. Early thrust-related inversion of rift basins is followed by a switch to rapid vertical exhumation, with deformation along steep reverse/normal faults. This vertical tectonics is related to a positive buoyancy force of the European crust induced by lower crustal delamination of the Aar Massif during an orogenic rollback process of the European lithosphere (∼22-20Ma). Differential rock uplift rates of up to 1.3–1.6km/Myr resulted, which decreased northwards to 0.1km/Myr. Reducing buoyancy forces (isostatic compensation) led to a horizontal tectonic style again. Persisting compressional forces induced an orogen-scale strain partitioning with dextral transpressive faults in the south and simultaneous crustal-scale northwest-directed thrusting in the north. ‘En-bloc’ exhumation of the entire Aar Massif in the thrust’s hanging wall occurred between 13-5 Ma and 5-0 Ma at rates of 0.5-0.9km/Myr and 0.6-0.8km/Myr, respectively. It is this late-stage thrusting in combination with surface erosion, which shaped today’s prominent Northalpine front. Switches between horizontal and vertical tectonics might generally be relevant for late continent-continent collisional stages. Here, buoyancy forces of non-thinned continental crust entering the subduction zone cause a strong vertical tectonic deformation style instead of classical thrust tectonics.