Analysis of analogue models testing the influence of rheologically weak layers and basal fault kinematics on deformation in the overburden

This data set includes overviews depicting the surface evolution (time-lapse photography, topography analysis, digital image correlation [DIC] analysis), as well as and progressive physical cross-section analysis of 18 laboratory experiments (analogue models) testing the influence of rheologically weak layers (i.e. layers with [a component of] viscous behaviour) and basal fault kinematics on deformation in the weak layer’s overburden. This model set-up was inspired by the geological situation in the Swiss Alpine Foreland. All experiments were performed at the Tectonic Modelling Laboratory of the University of Bern (UB). Detailed descriptions of the model set-up preparation and results, as well as the monitoring techniques can be found in Zwaan et al. (in review).

We use a model set-up involving a deformable base to simulate a basal fault that induces deformation in an overlying weak layer, which itself is overlain by a more competent overburden (Figs. 1, 2). The total thickness of these model materials is 6.5 cm. The deformable base consists of a mobile and a fixed base plate that are both 2 cm thick, with the contact between these two base plates representing a steep, 75˚ dipping fault plane (or velocity discontinuity: VD). Furthermore, each base plate is attached to a longitudinal sidewall. The initial space between these longitudinal sidewalls is 30 cm, and the length of the model set-up is ca. 80 cm. The mobile base plate, together with the sidewall attached to it, can move outward (y-axis), downward (z-axis) and right-laterally (x-axis) by means of computer-controlled motors. By combining these three motion directions, we simulate pure normal dip-slip, 45˚ oblique normal dip slip, or pure dextral strike-slip fault kinematics (Fig. 1b, e). Furthermore, higher faults slip rates than the reference 10.4 mm/h can be applied.