This dataset provides friction data from ring-shear tests on garnet sand used in analogue modelling of tectonic processes as a rock analogue for “strong” or “high density” layers in the earth’s upper crust (e.g. Klinkmüller et al., 2016).

According to our analysis the material shows a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of garnet sand are µP = 0.83, µD = 0.61, and µR = 0.73, respectively (Table 5). Cohesion of the material ranges between 20-120 Pa. The material shows a no significant rate-dependency.

The data presented here are derived by ring shear testing using a SCHULZE RST-01.pc (Schulze, 1994, 2003, 2008) at HelTec, the Laboratory for experimental tectonics at the Helmholtz Center Potsdam – GFZ German Research Centre for Geosciences in Potsdam, Germany. The RST is specially designed to measure friction coefficients µ and cohesions C in loose granular material accurately at low confining pressures (<20 kPa) and shear velocities (<1 mm/sec) similar to sandbox experiments. In this tester, a granular bulk material layer is sheared internally at constant normal stress σN and shear velocity v while shear force and lid displacement (corresponding to density and volume change ΔV) are measured continuously. For more details see Klinkmüller et al. (2016).