Stress-dependent nonlinear upper mantle rheology has a firm base in rock mechanical tests, where this nonlinearity results from dislocation creep of minerals. In the last few decades there has been some attention to nonlinear, power-law, materials for application in scaled analogue experiments for tectonic processes. However, studies describing the rheology of analogue materials with the same nonlinear dependency on stress as observed for lithospheric mantle materials at relevant stress levels, are still lacking. In this study we have developed and rheologically tested materials based on combinations of silicone polymers and plasticine, with the aim of obtaining a material that can serve as a laboratory analogue to the power-law rheology of olivine aggregates at lithospheric mantle conditions. From our steady-state creep tests we find that it is possible to obtain such a power-law material, with effective viscosities over relevant model stress ranges [5–4000 Pa] that allow for nonlinear deformation at laboratory time scales. We apply the developed material to a process where localized deformation of the lithosphere can be expected: slab break-off. We study this process using analogue models, where we apply the new nonlinear material to the lithospheric mantle domains, while we use Newtonian glucose to represent the low viscous asthenosphere. Now that we properly manage power-law behavior in our analogue lithosphere materials, we are able to model localized lithospheric tearing.

The sea floor of intraslope minibasins on passive continental margins plays a significant role in controlling turbidity current pathways and the resulting sediment distribution. To address this, laboratory analogue modelling of intraslope minibasin formation is combined with numerical flow simulations of multi-event turbidity currents. This approach permits an improved understanding of evolving flow–bathymetry–deposit interactions and the resulting internal stacking patterns of the infills of such minibasins. The bathymetry includes a shelf to slope channel followed by an upper minibasin, which are separated by a confining ridge from two lower minibasins that compares well with analogous bathymetries reported from natural settings. From a wider range of numerical flow experiments, a series of 100 consecutive flows is reported in detail. The turbidity currents are released into the channel and upon reaching the upper minibasin follow a series of stages from short initial ponding, ‘filling and spilling’ and an extended transition to long retrogradational ponding. Upon reaching the upper minibasin floor, the currents undergo a hydraulic jump and therefore much sediment is deposited in the central part of the minibasin and the counterslope. This modifies the bathymetry such that in the fill and spill stage, flow stripping and grain-size partitioning cause some finer sediment to be transported across the confining ridge into the lower minibasins. Throughout the basin infill process, the sequences retrograde upstream, accompanied by lateral switching into locally formed depressions in the upper minibasin. After the fill and spill stage, significant deposition occurs in the channel where retrograding cyclic steps with wavelengths of 1 to 2 km develop as a function of pulsating flow criticality. These results are at variance with conventional schemes that emphasize sequential downstream minibasin filling through ponding dominated by vertical aggradation. Comparison of these results with published field and experimental examples provides support for the main conclusions.