Most of my work concerns the lithospheric deformation during continental collisions. I mainly focussed on the debate on deformation localisation: - Is deformation mostly localised along a few great fault zones, or is it mostly distributed on many small structures? - Localisation clearly occurs in the upper brittle part of the crust. Is deformation also localised in the lower ductile crust and in the upper mantle? - In other words, should deforming continents be seen as a pack of rigid blocks floating on a viscous lower crust, or as large coherent lithospheric blocks? More than 30 years after the plate tectonics revolution such questions could appear trivial. This is, however not the case mostly because of the difficulty to define what is the relevant time scale. Sismologic and geodesic studies allow to characterise precisely active deformations. However, suh observations corespond to a very short time window: less than 0,001% of the total collision time span. One may thus wonder of their exact significance. On the other hand, geological structures correspond to a final state, often resulting from several deformation phases, difficult to decipher and further more to quantify.

It is difficult to detemine how was the deformation absorbed at a given time (or during a given deformation phase lasting few million years),

In order to answer to the questions of strain localisation we thus have to work on well constrained examples where the cinematics within the system and at its boundaries can be retrieved.

I conducted my research activities following four main guidelines. (1) My work is based on the gathering of field data. (2) My studies integrate observations at all scales. (3) Ductile deformations are characterised by a multidisciplinary approach combining structural, petrographic and geochronological constrains in order to reconstruct P-T-t-D (Pressure-Temperature-time-Deformation) paths. (4) I focussed on well-constrained examples, mainly the India-Eurasia collision zone. Beyond regional studies (Asia, Alps) our goal is to understand the mechanics of large ductile shear zones and to characterise the mode of deformation localisation in time and space in the continental lithosphere.

In SE Asia we have confirmed the importance of large strike-slip fault zones during the collision with India. For the first time we even could measure a strike-slip rate on a ductile shear zone: the Ailao Shan ­ Red River shear zone. In the Alps we presently focus on the timing and mode of exhumation of the highest parts of the mountain range: the external crystalline massifs and the Mont Blanc massif in particular.

The Ailao Shan - Red River shear zone and cenozaic Sundaland extrusion	The Karakorum fault
Himalayan orogeny: structural, petrographic and geochronologic constraints	The eastern border of Tibetan plateau
Active normal faults in Tibet	paleo-stress and paleo strain rate measurements in shear zones
Alpine external cristaline ranges exhumation including the Mont Blanc	Late deformation in alpine internal zone  including the Insubric fault and the Bergell range
paleo-altitude estimates in the Alps and Tibet

Last update: 10-22-2009

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