Rhéologie et déformation de la lithosphère continentale : apports de mesures GPS en Asie et de modèles numériques

Abstract : In this work we study the current kinematic of Mongolia in the northern part of Asia and the dynamics of the deformation in Mongolia and Asia First we present the 1994-2002 Mongolia-Baikal GPS velocity field ( 50 sites) with respect to Eurasia Velocities show that 15% of the IN/EU convergence is accommodated north of the Tien Shan by N-S shortening and dextral shear in the Altay mountain and by E-SEward displacement of central and eastern Mongolia at 3-6 mm/yr Our results suggest that the Eward motion in Asia could be controlled by other processes than the IN/EU convergence such as the dynamic of the oceanic subduction zone or the gravitational potential energy gradient Then starting with the large mongolian EQ of the last century and the GPS velocities we model the postseismic deformation (current viscoelastic relaxation < 2mm/an) and estimate the lithosphere rheology under Mongolia (weak upper mantle and lower crust) Next with a study on viscoelastic and static stress transfer we suggest that significant stress transfer is possible among continental faults separated by 100s of km and on time scales of decades Finally we validate dynamic deformation models of Asia with a GPS velocity field covering most of Asia We estimate the average lithosphere rheology and quantify the different mechanisms of deforma- tion We show that the IN/EU collision is the major contribution to the asian deformation However the deformation in north and east Asia is also controlled by the body forces and the dynamic of the oceanic subduction zone Our results suggest that the deformation is mostly continuous but this last point should be confirmed by further measurements
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Mathilde Vergnolle. Rhéologie et déformation de la lithosphère continentale : apports de mesures GPS en Asie et de modèles numériques. Géophysique [physics.geo-ph]. Université Nice Sophia Antipolis, 2003. Français. ⟨tel-00653541⟩

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