The analogue modeling of boudins

Boudins are geologic structures, formed by the extension of a brittle layer, which is sandwiched between two ductile layers. In this work, experiments with non-scaled analogue models were made to investigate the parameters that control the evolution of boudin blocks. For these experiments a singleviscous-layer setup was used, which had of course some restrictions, but was simple to build and showed the principles that are analyzed here. Different experiments were performed with radial extension, unidirectional and bidirectional extension, different thicknesses of the brittle layer and disruptions in the flow of the viscous layer. The analysis showed a dependence of the boudin width on the brittle layer’s thickness and the extension-rate. Furthermore, point-track images of selected experiments showed the flow directions which are responsible for complex boudin movements and rotations. The evolution of relay-ramps was investigated, as well as the forming of fractures within the brittle layer