RESTORATION OF THE PREOROGENIC EUROPEAN PLATFORM FROM THE BRESSE TO THE SUB-ALPINE CHAINS - KINEMATICS OF ALPINE DEFORMATION (FRANCE AND WESTERN SWITZERLAND)

In the transect of transition from the central to the western part of the alpine arc (Western Switzerland and France) a palinspastic restora tion of the alpine foreland is tempted, including the Subalpine Chains (Aravis and Bornes), the Molasse basin and the Jura mountains. Major problems in this reconstruction at the virgation of the chain are: (1) the changing directions of tectonic transport during deformation; (2) the lack of information on the geometry of strike slip faults (and la teral limitations of thrust sheets) and of the amount of tectonic disp lacement along these faults; (3) the lack of information about the int ernal architecture of the main anticlinal structures of the Jura and t he Subalpine Chains. In the Tabular Jura, N-S shortening is limited to minor thrusts. The Plateau Jura, with little transpressive deformatio n along the ''faisceaux'', has been thrusted in Late Miocene and Plioc ene times to the NW and W on the top of the Bresse basin by a mean dis tance of about 8 km. In the Folded Jura, the High-Chain of the Central Jura, with strong N S shortening by thrusting and folding (maximum 20 km), is separated from the less deformed Southern Jura (6 to 8 km int ernal E-W shortening) by the Vuache-Forens-Les Bouchoux strike-slip fa ult zone, which is linked to the alpine front by the Vuache-Annecy lef t lateral strike-slip fault and by the Alby structure. Strain markers indicate changing transport directions from N-S to E-W during the defo rmation of the Jura, from Early Miocene to now. In the Subalpine chain s, a first deformation phase (mainly Oligocene and Early Miocene) indi cates SSE NNW to SE NW shortening by folding and thrusting of about 8 km, and a second phase is at the origin of 6 km of thrusting from the ESE or E to WNW or W (mainly Miocene and Pliocene).