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Drained ring-shear test data of wet silica powder-glass beads-PVC powder mixture “CM2” used for analogue modelling in the laboratory for experimental tectonics (LET) at RomaTre University, Rome, Italy

This dataset provides friction data from drained ring-shear tests on a wet (water saturated) silica powder-glass beads-PVC powder mixture (40:40:20 wt.%) “CM2”, used in analogue modelling of tectonic and erosion processes as a rock analogue for the earth’s upper crust (e.g. Conrad et al., 2023, Reitano et al., 2020, 2022. 2023). According to our analysis the materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of CM2 are µP = 0.66, µD = 0.58, and µR = 0.61, respectively. Cohesion of the material ranges between 60-230 Pa. The tested bulk material CM2 consists of a mixture of 40 wt. % silica powder, 40 wt.% glass beads and 20 wt.% PVC powder which has been saturated with water (Table 1). Specification of silica powder is “Ventilated Quartz VR16” (https://www.valligranulati.it/products-granules-quartz-marble-sands-premixed/sheet-m/ventilated-quartz) by the company Valli Granulati S.r.l. (Italy). Ventilated quartz is obtained by micronisation of quartz sands with a high content of SiO2 (around 96%), and used e.g. in paints and abrasives. It should be handled with care to omit generation of dust and a half mask (filter class FFA1P2 RD) should be worn because it can harm the human respiratory tract with the potential of causing silicosis. Glass beads used here have a size (diameter) of 700-110 µm and their individual properties are described in detail Pohlenz et al. (2020). The commercial name for the PVC powder is “PVC K.57 Inovyn 257RF” by the company TPV Compound (Italy). PVC powder is mainly used for cleaning industrial structures (as abrasives) or for the production of PVC tubing, plastic sheets etc. The composition of this PVC powder is the same of the common Polyvinyl chloride. According to the regulation CE n.1272/2008 (CLP), this type of PVC powder is classified as not dangerous for the supply, also thanks to its low value of density and round shape.

Rheology of PDMS silicones used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (CUP)

This dataset provides rheometric data of three PDMS silicones used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (CUP). The material samples have been analyzed at the Laboratory for Experimental Tectonics at GFZ Helmholtz Centre for Geosciences, Potsdam (HelTec) using an Anton Paar Physica MCR 301 rheometer in a plate-plate configuration at room temperature (21˚C). Rotational (controlled shear rate) tests with shear rates varying from 10^4 to 1 s^-1 were performed. According to our rheometric analysis, the material is quasi-Newtonian (n~1) at strain rates below 10-2 s-1 and weakly shear rate thinning above. The viscosities of the three materials range between 8*10^4 to 3*10^5 Pa s.

Ring-shear test data of corundum sand “NKF120” used for analogue modelling in the experimental tectonics laboratory at GFZ Potsdam

This dataset provides friction data from ring-shear tests on corundum sand “NKF120” 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) or as an additive to PDMS silicone oil to increase its density and non-linearity (Zwaan et al., 2018). According to our analysis the material shows a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.75, µD = 0.57, and µR = 0.62, respectively (Table 5). Cohesion of the material ranges between 100-150 Pa. The material shows a minor rate-weakening of ~1% per ten-fold change in shear velocity v and a stick-slip behaviour at low shear velocities. The tested bulk material consists of corundum sand with grain size of 90-120 µm (Table 1). Corundum sand is produced as industrial abrasive materials and sold e.g. by the company Nico Bosse Strahlmittel Berlin. 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.

Ring-shear test data of wallnut shells used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing))

This dataset provides friction data from ring-shear tests walnut shells used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the tested materials behave as a Mohr-Coulomb material characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.90, µD = 0.63, and µR = 0.68, respectively (Table 4). Cohesion of the material ranges between 0-40 Pa. The tested bulk material consists of walnut shells with grain size of 180-380 µm (Table 1) and is sold under the name "Walnut Shells" with the product number YR-98547 by the company Yiran Mineral Products (1688.com). 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).

Ring-shear test data of foamglass used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing)

This dataset provides friction data from ring-shear tests foamglass used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.55, µD = 0.52, and µR = 0.57, respectively (Table 4). Cohesion of the material ranges between 10-30 Pa. The tested bulk material consists of foamglass with grain size of 180-380 µm (Table 1) and is sold under the name "Floating Bead" with the product number PZ-002 by the company Tuyun Mineral Products (1688.com). 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).

Ring-shear test data of mica used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing)

This dataset provides friction data from ring-shear tests black mica used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.59, µD = 0.56, and µR = 0.57, respectively (Table 4). Cohesion of the material ranges between 100-130 Pa. The tested bulk material consists of black mica (Biotite) with grain size of 380-830 µm and is sold under the name "Black Mica" with the product number YS-004 by the company Yunshi Building Materials Co., Ltd (1688.com). 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).

Ring-shear test data of quartz sand SIBELCO S80 used for analogue modelling in the Tectonic Laboratory (TecLab) at Utrecht University

This dataset provides friction data from ring-shear tests on quartz sand SIBELCO S80 used in analogue modelling of tectonic processes as a rock analogue for 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 quartz sand S80 are µP = 0.75, µD = 0.59, and µR = 0.69, respectively (Table 5). Cohesion of the material ranges between 0-80 Pa. The material shows no rate-dependency (<1% per ten-fold change in shear velocity v). The tested bulk material consists of quartz sand SIBELCO S80 with grain size of ~0.63-355 µm (D50 = 175 µm. Bulk and grain densities are 1300 kg/m³ and 2650 kg/m³, respectively and the hardness is 7 on Moh’s scale. S80 is sold e.g., by the company SIBELCO (sibelco.com).

Ring-shear test data of colored quartz sand used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing)

This dataset provides friction data from ring-shear tests colored quartz sand used for analogue modelling in the experimental tectonics laboratory at China University of Petroleum (Beijing). According to our analysis the materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of corundum sand are µP = 0.75, µD = 0.59, and µR = 0.67, respectively (Table 5). Cohesion of the material ranges between 20-90 Pa. The tested bulk material consists of blue colored quartz sand with grain size of 180-380 µm and is sold under the name "Colored Sand" with the product number A1 by the company Xinran Mineral Products (1688.com). 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 experi-ments. 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 vol-ume change ΔV) are measured continuously. For more details see Klinkmüller et al. (2016).

Ring Shear and Slide-Hold-Slide Test Measurements for Soda-Lime Glassbeads of 300-400µm diameter used at the Helmholtz Laboratory for Tectonic Modelling, Potsdam, Germany

This data set provides two series of experiments from ring-shear tests (RST) on glass beads that are in use at the Helmholtz Laboratory for Tectonic Modelling (HelTec) at the GFZ German Research Centre for Geosciences in Potsdam. The main experimental series contains shear experiments to analyse the slip behaviour of the granular material under analogue experiment conditions. Additionally, a series of slide-hold-slide (SHS) tests was used to determine the rate and state friction properties. A basic characterisation and average friction coefficients of the glass beads are found in Pohlenz et al. (2020). The glass beads show a slip behaviour that is depending on loading rate, normal stress and apparatus stiffness which were varied systematically for this study. The apparatus was modified with springs resulting in 4 different stiffnesses. For each stiffness a set of 4 experiments with different normal stresses (5, 10, 15 and 20 kPa) were performed. During each experiment loading rate was decreased from 0.02 to 0.0008 mm/s resulting in 9 subsets of constant velocity for each experiment. We observe a large variety of slip modes that ranges from pure stick-slip to steady state creep. The main characteristics of these slip modes are the slip velocity and the ratio of slip event duration compared to no slip phases. We find that high loading rates promote stable slip, while low loading rates lead to stick-slip cycles. Lowering the normal stress leads to a larger amount of creep which changes the overall shape of a stick-slip curve and extends the time between slip events. Changing stiffness leads to an overall change in slip behaviour switching from simple stick-slip to more complex patterns of slip modes including oscillations and bimodal slip events with large and small events. The SHS tests were done at maximum stiffness and higher loading rates (>0.05 mm/s) but at the same normal stress intervals as the main series. Using various techniques, we estimate the rate-and-state constitutive parameters. The peak stress after a certain amount of holding increases with a healing rate of b=0.0057±0.0005. From the increase in peak stress compared to the loading rate in slide-hold-slide tests we compute a direct effect a=-0.0076±0.0005 which leads to (a-b)=-0.0130±0.0006. Using a specific subset of the SHS tests, which have an equal ratio of hold time to reloading rate, we estimate (a-b)=-0.0087±0.0029. Both approaches show that the material is velocity weakening with a reduction in friction of 1.30 to 0.87 % per e-fold increase in loading rate. Additionally, the critical slip distance Dc is estimated to be in the range of 200 µm. With these parameters the theoretical critical stiffness kc is estimated and applied to the slip modes found in the main series. We find that the changes in slip mode are in good agreement with the estimated critical stiffness and thus confirm the findings from the SHS tests.

Ring-shear test data of garnet sand used for analogue modelling in the experimental tectonics laboratory at GFZ German Research Centre for Geosciences, Potsdam

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).

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