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The inverted margin of the French Alps and foreland basin inversion

1989; Geological Society of London; Volume: 44; Issue: 1 Linguagem: Inglês

10.1144/gsl.sp.1989.044.01.06

2041-4927

P. C. de Graciansky, G. Dardeau, Maël Lemoine, Pierre Tricart,

Geological and Geophysical Studies Worldwide

Summary The whole of the Western Alpine realm can be considered to result from the inversion of the European margin of Ligurian Tethys as a consequence of the collision between Apulia and Europe. The margin was developed due to Tethyan rifting during the Liassic and Middle Jurassic and regional thermal subsidence as the Ligurian ocean was spreading in the Late Jurassic and Early Cretaceous. Coevally, the margin underwent additional stretching in response to North Atlantic rifting. Inversion was initiated by Late Cretaceous times when the Ligurian oceanic crust began to be subducted, with localized obduction, beneath the previously passive margin. The most recent inversion of the Western Alps occurred in the external Molasse basin of Manosque-Digne-Valensole during the Late Miocene and Pliocene. Regions of mild inversion allow useful comparisons to be made with more strongly inverted basins. The geometric characteristics of the inverted basins depend on the lithology, geometry of the extensional structures, orientation of extensional faults with respect to the compressive Alpine stresses and the amount of compression. Comparisons of the external and interal zones suggest that the ductilely deformed thrust sheets may have originated from inverted half-grabens.