Data from structural geology, paleomagnetism and thermochronology provide the basis for an integrated reconstruction of the Oligocene to Present kinematic evolution of the north-western alpine nappe stack. Two brittle tectonic phases post-date the Cretaceous-Eocene ductile deformations. A NW-SE extension developed in the Oligocene (D1) along three main conjugate fault systems arranged in an orthorhombic symmetry (N-, NW- and SE-dipping). Syn-kinematic hydrothermal veins and calc-alkaline dikes (29-32 Ma) indicate the Oligocene age of this phase, whilst cooling rate contour maps highlight the differential exhumation of large fault-bounded blocks. In the Miocene, a general re-arrangement of the strain pattern lead to a SW-directed lateral escape (D2), continuing to the Present, of the Pennine-Graian Alps (PGA) block. This block is bounded by a network of seismogenic shear zones, the most important being the Ospizio Sottile, Simplon, Rhone and Chamonix faults. The internal deformation of the PGA block is characterized by an overall almost homogeneous NE-SW extension. The D1 and D2 tectonic phases, developed in the Penninic-Austroalpine nappe stack, could have been induced by the progressive evolution of the slab break-off process and by the following lithospheric overthickening. The large faults studied during this thesis must be taken into account in the reconstruction of ductile structures of the Penninic-Austroalpine nappe stack, which can not be considered cylindrical any longer.

(2000). Tettonica Neoalpina nelle Alpi Nord-Occidentali.. (Tesi di dottorato, Università degli Studi di Padova, 2000).

Tettonica Neoalpina nelle Alpi Nord-Occidentali.

BISTACCHI, ANDREA LUIGI PAOLO
2000

Abstract

Data from structural geology, paleomagnetism and thermochronology provide the basis for an integrated reconstruction of the Oligocene to Present kinematic evolution of the north-western alpine nappe stack. Two brittle tectonic phases post-date the Cretaceous-Eocene ductile deformations. A NW-SE extension developed in the Oligocene (D1) along three main conjugate fault systems arranged in an orthorhombic symmetry (N-, NW- and SE-dipping). Syn-kinematic hydrothermal veins and calc-alkaline dikes (29-32 Ma) indicate the Oligocene age of this phase, whilst cooling rate contour maps highlight the differential exhumation of large fault-bounded blocks. In the Miocene, a general re-arrangement of the strain pattern lead to a SW-directed lateral escape (D2), continuing to the Present, of the Pennine-Graian Alps (PGA) block. This block is bounded by a network of seismogenic shear zones, the most important being the Ospizio Sottile, Simplon, Rhone and Chamonix faults. The internal deformation of the PGA block is characterized by an overall almost homogeneous NE-SW extension. The D1 and D2 tectonic phases, developed in the Penninic-Austroalpine nappe stack, could have been induced by the progressive evolution of the slab break-off process and by the following lithospheric overthickening. The large faults studied during this thesis must be taken into account in the reconstruction of ductile structures of the Penninic-Austroalpine nappe stack, which can not be considered cylindrical any longer.
Dal Piaz, G.V.
Lanza, R.
tettonica neoalpina, Alpi Nord-Occidentali
Italian
Dottorato di Ricerca in Scienze della Terra
12
2000
(2000). Tettonica Neoalpina nelle Alpi Nord-Occidentali.. (Tesi di dottorato, Università degli Studi di Padova, 2000).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/39207
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