Analogue Modelling

The Structural and Analogue Modelling Laboratory is part of the Research Center for Integrated Geological Studies, Geology Department, Babes-Bolyai University, Cluj-Napoca. With the existing analogue modelling apparatuses, we are capable of modelling and monitoring deformation in regimes from compression to extension and strike-slip (including transpression and transtension). The modelling apparatuses are powered by a Nema 34 stepper motor, with a holding torque of 7.7 Nm. The motor controller and software are self-designed and are based on Arduino & Processing.

Cross-sections through an analogue model located in the central area of the experiment and the interpretation (Tamas et al. 2019). On the right of the interpreted section, the total contribution of penetrative strain (green), thrusting and folding (red) is illustrated. On the left there is a top-view map illustrating the PIV velocity magnitude between 24% and 33% shortening.

Deformation is monitored using digital DSLR cameras, X-Box Kinect 360 IR camera and projector, structured light scanner, and force sensors (strain gauges). Based on the time-lapse images acquired by the DSLR cameras and the use of digital image correlation techniques (Particle Image Velocimetry – PIV) in MATLAB (PIVLab software), displacement vectors are computed. From these, several attributes like velocity magnitude (general and for separate axis), strain rate, divergence, cumulative displacement, etc., can be calculated. Force sensors are also used in some models, with the scope of better understanding the kinematics of model deformation (in cylindrical models). The Kinect camera is used together with a modified version of the AR Sandbox software to acquire Digital Elevation Models (DEM) of the experiments.

After the models are finalised, they are wetted using a water-gelatin mixture. Closely spaced serial sections are cut and photographed. The section photographs, together with the PIV and DEM are used to better interpret and understand model deformation (in software like: Move, Petrel, OpendTect, ArcGIS, etc.). In some cases, 3D voxel models are reconstructed from the serial cut sections with the scope of visualising other section orientations (i.e. horizontal) within the model (using image processing and scientific visualisation software – MeVisLab or ImageJ).

The commonly used modelling materials for the brittle behaviour are dry, coloured, nearly pure silica sand, glass microspheres and kaolin, while for modelling the viscous behaviour we use PDMS Silicone.

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