International Geologiical Congress - Oslo 2008

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STT-08 Numerical and analogue modelling of deformation - from the micro- to the crustal scale

 

Kinematic evolution of tectonic wedges using physical and numerical models

 

Leonardo Cruz, Stanford University (United States)
George Hilley, Stanford University (United States)
Andy Take, Queen's University (Canada)
 

 

In this study, we compare state-of-the-art analogue modeling techniques and finite element models under comparable boundary conditions to quantify the variability of wedge kinematics between these techniques and understand its causes. In the physical models, our contractional experimental apparatus (sandbox) includes a load cell with a servo feedback system that allows for a variety of boundary conditions to be applied to the moving wall, including constant displacement rate, time-varying displacement rate, constant loading, and time-varying loading. This particular experimental design allows us to investigate feedbacks between shortening rates and surfaces processes (erosion) that have not been studied before in analogue modeling. We apply Particle Image Velocimetry (PIV) techniques to digital images from the experimental model to derive high-resolution kinematics and calculate strain, uplift and exhumation rates. We used granular materials with different frictional properties including cohesion, friction coefficient and density, which can be simulated in the numerical box. These materials include silica sand, glass beads and walnut shells, with various grain sizes. In the numerical models, we use the finite element code GALE that allows, among other things, the simulation of an experimental box under contraction, in 2D and 3D, and permits the modification of boundary conditions, mass fluxes, rheologies, and crustal shapes. Preliminary results indicate that high-resolution kinematics derived from PIV technique can be compared directly to 2D/3D numerical simulations. The kinematic evolution of the physical and numerical tectonic wedge under similar boundary conditions is currently being studied in detail.

 

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