A novel analogue modelling approach for studying lithospheric deformation driven by asthenospheric flow with implications for extensional back-arc basins

Abstract

Asthenospheric flow is a major driver of plate tectonics and lithospheric deformation. Previous studies have modelled the asthenospheric flow linked to the negative buoyancy and rollback of subducting slabs, which is associated with complex patterns of asthenospheric flow. This flow is associated with large-scale lithospheric processes, such as upper plate orogenic rotations, strain partitioning or the along-strike variability of subduction mechanics. In this complex interaction, understanding the asthenospheric contribution to upper plate deformation requires a bottom-up approach that simulates the asthenospheric flow and its effects on the overlying lithosphere. Here, we present a novel physical analogue modelling approach where gravity-driven asthenospheric flow is the main driver for lithospheric deformation. An asthenospheric flow with a constant volume is created by a novel inlet-outlet system that allows calibration of the flow velocity, which controls the lithosphere-asthenosphere coupling. Our novel approach induces asthenospheric flow, which provides an efficient mechanism for transferring deformation to a mechanically stratified lithosphere, where deformation can be studied in greater detail when compared with previous physical analogue modelling studies. Our approach is validated by a comparison with the slab retreat-driven back-arc extension observed in the Carpathians-Pannonian system of Central Europe. Beyond slab retreat mechanics, our approach can be further used for modelling asthenospheric flow in other plate tectonics settings.