Abstract. -Southeast Asia represents a valuable playground for studying the mechanisms of supra subduction mountain building. Fast relative plate velocities induce rapid geodynamic changes, so that the parameters for the convergence can be constrained, whereas the recently inactivated systems are still accessible. We make use of the GPS-controlled motion of major plates together with that of smaller units within the deformed belts, to explore the Neogene evolution of SE Asia. We present simplified synthetic sections for the structural control, and used GIS-based reconstructions to support the relative location of the plates and distances between them, so that at a given time, location of units can be confronted to the tectonic observations. Pericratonic mountain ranges are the result of long lasting convergence which was responsible for both the fragmentation of continental landmasses by the opening of marginal basins, and the shortening of these supra subduction units, which ultimately jammed them back against the motherland, or transferred them to the neighbouring plate. Because the obliquity of the convergence generated strain partitioning, new paired trench and strike-slip systems are created, moving blocks further away from the locus of accretion, so that continental or oceanic fragments may be chopped, transported and eventually severely sheared during final docking. We present simplified cross sections of the margins of the SE Asian regions prior and after the accretions of blocks and reconstructions at 2, 4, 6, 10, 15 and 20 Ma.
L'édification des chaînes péricratoniques, contraintes structurales et cinématiques appliquées aux reconstructions de l'Asie du SE sur SIGMots-clés. -SE Asiatique, Reconstructions cinématiques, Convergence, Chaîne de montagne péricratonique, SIG.Résumé. -Le SE asiatique est un chantier qui permet d'étudier la formation des chaînes de montagnes situées au dessus des zones de subduction à différents stades de leur évolution. Dans ces régions, la cinématique des plaques est extrême-ment rapide, souvent de l'ordre de 10 cm/an, et la convergence engendre l'ouverture, elle aussi rapide, de bassins marginaux qui fragmentent sous forme de lanières les masses continentales. Les fragments ainsi séparés comportent donc un substratum généralement constitué de matériel correspondant à des ophiolites de supra subduction (arc, avant-arc, arrière-arc) ainsi que des reliques de croûte continentale. Ce type de mécanisme aboutit à la formation de plaques étirées qui peuvent être soit de nature océanique comme pour la plaque Philippine [Karig, 1975] formée de bassins arrière-arcs