Publication Date:
2014-04-05
Description:
The kinematics of the collision in Western Alps are investigated through five balanced cross-sections of the whole external domain from the Oisans massif in the South to the Mont Blanc massif in the North. These cross-sections were built using published data for the Jura and subalpine fold-and-thrust belts and new structural and field analysis for the External Crystalline Massifs. Five units are defined: the sedimentary nappes from inner most parts of the external zone (e.g., ultra-Dauphinois/Helvetic), the crystalline units with their dysharmonically folded cover (e.g., Morcles nappe), sedimentary nappes over the frontal parts of the crystalline massifs (the Aravis-Granier unit), the subalpine belts (e.g., Vercors, Chartreuse, Bauges, Bornes), and the Jura. Except for the ultra-Dauphinois nappes, the shortening, including the cover shortening, always corresponds to basement shortening. The total amount of shortening increases from south (28 km, 20%) to north (66 km, 27%). Moreover, the shortening is slightly older in the south than in the north; deep-water turbidites (flysch) and shallow marine to fresh water clastics (molasse) basins are more developed in the north; P,T conditions are higher in the north; the average uplift rates are about three times higher in the north and more localized in space. We propose that these differences are due to along strike variations in the structure of the European continental margin inherited from Mesozoic times. We then build five palinspastic maps: one at Cretaceous times showing the inherited European Mesozoic margin structure and four from Priabonian to upper Miocene times showing the collision kinematics and the related rotation of Adria.
Print ISSN:
0278-7407
Electronic ISSN:
1944-9194
Topics:
Geosciences
Permalink