-We conducted a series of analogue experiments on shortening of a brittle cover (dry sand) above a deep, thin, frictional detachment (glass microbeads). In some experiments, the cover was homogeneous, entirely brittle. In others, there was a thin viscous silicone layer (representing salt) embedded at mid height into the cover, and initially located in the foreland of the fold-and-thrust belt. Our goal was to determine whether or not the presence of such a dĂ©collement in the cover could have an impact on the mechanics and kinematics of the underlying subsalt thrusts. Results confirm that, once the front of the foldbelt reached the hinterland salt pinch out, the kinematics of the deeper belt changed drastically: its front stopped propagating forward, and most of the subsequent shortening was accommodated by a larger-than-normal slip along the foremost and youngest deep thrust, while, above the salt dĂ©collement, the deformation front propagated very fast, creating a very low surface slope. We hypothesize that it is the gentle sub-critical surface slope associated with rocksalt's low viscosity that prevents the build-up of an overall surface slope steep enough to allow the underlying, deep foldbelt to continue propagating forward. Finally, one experiment in which only one half of the width of the model comprised an interbedded viscous dĂ©collement has shown that the kinematics of the deep thrust was affected even in the adjacent salt-free domain.Keywords: salt tectonics / fold-and-thrust belts / analogue modeling / dĂ©collement RĂ©sumĂ© -Influence de la prĂ©sence d'un niveau de dĂ©collement Ă©vaporitique situĂ© au sein de la couverture sur l'Ă©volution des chevauchements sub-salifĂšres profonds lors de la propagation d'une chaĂźne d'avant-pays. Nous avons rĂ©alisĂ© une sĂ©rie d'expĂ©riences de modĂ©lisation analogique Ă©tudiant le raccourcissement d'une couverture sĂ©dimentaire constituĂ©e de matĂ©riel fragile (sable sec) enracinĂ©e sur un niveau profond frictionnel (microbilles de verre), mais comprenant localement une couche visqueuse interstratifiĂ©e de plus faible rĂ©sistance mĂ©canique (polymĂšre de silicone). Le but de ces expĂ©riences Ă©tait d'analyser l'impact d'un tel niveau de dĂ©collement visqueux superficiel sur la mĂ©canique et la cinĂ©matique des chevauchements de la zone profonde, et notamment sur les modalitĂ©s de la transmission de la dĂ©formation entre les deux niveaux de dĂ©collement. Les rĂ©sultats expĂ©rimentaux confirment bien que, lorsque le front de dĂ©formation profond atteint la rĂ©gion oĂč se trouve la sĂ©rie visqueuse interstratifiĂ©e, la cinĂ©matique des chevauchements profonds change de façon drastique. Le front de dĂ©formation profond cesse de se propager vers l'extĂ©rieur du modĂšle, et le chevauchement profond le plus jeune se connecte avec le niveau de dĂ©collement superficiel. Ainsi, la plus grande partie du raccourcissement est transmise aux sĂ©ries superficielles de la couverture. Le front de dĂ©formation migre rapidement vers l'extĂ©rieur en se propageant sur le niveau Ă faible rĂ©sistance mĂ©canique. La pente topograp...