Simulation of lithospheric-plate collision by using DEM. Example of the Arabian platform motion
Por:
Parrot J.-F., Collet B.
Publicada:
1 ene 2009
Resumen:
A high resolution Digital Elevation Model (DEM) is used to simulate and quantify the consequence of lithospheric-plate confrontation. The algorithm takes into account the calculated mountainous chain and the reconstitutions of the original formation steps. The procedure consists in applying to the DEM a mask composed of two different limits, namely i) a fixed and ii) a moving limit (see figure). The moving limit is displaced in an iterative way, until reaching the initial position of the punching plate. The extrapolation of the altitude values on a given transect takes into account i) the initial distance D inbetween the limits before moving, ii) the distance Dout between the fixed limit and the new position of the moving limit, and iii) the original altitude of the points encountered in the transect. On the other hand, two regions are located outside of the mask. The region located upstream on the transect remains unchanged, as the downstream region is moved according the moving limit motion, but without any modification of their altitude values. The DEM can be rotated in such a way that transects follow the columns, from the fixed to the moving limit. For this case, the algorithm inside the mask can be simplified, where i is the unique variable employed. If istart < i < iend-in then the altitude value (Aout) and the location (i?, j) of the pixel corresponding to the transformation are obtained from equations 7, 8 and 11 in the text. (Equation Presented). MaxD correspond to the step and the maximum displacement defined by the user, respectively. The computation of the altitude Aout (i?, j?) requires defining the minimum altitude value Amin of each studied transect. Comparing the altitude of the transect starting point A in(istart, jstart) and the altitude A in at the point (iend-in, jend-in), A min corresponds to the lower altitude value. In the presence of a punching point (see Fig. 4), the computation of elongation follows the formulas (7) and (8), yet the stretching applied to each transect depends on the value of Dout calculated as follows: Dout = Din + St? where St? = St X (Dmin / Din ) and D min is the distance in front of the punching point. As the motion of the pushing plate is directly related to the St value, the algorithm generates an empty space assumed to cor
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