HR: 0830h
AN: T21D-0485    [PDF]
TI: Discrete Element Simulations of Indentation Tectonics; Insights for Velocity and Stress Distributions
AU: * Yamada, Y
EM: yama@electra.kumst.kyoto-u.ac.jp
AF: Dept. of Civil and Earth Resources Engineering, Kyoto University, Yoshida-Honcho, Sakyo-ku, Kyoto, 606-8501 Japan
AU: Tanaka, A
EM: atsushi@tansa.kumst.kyoto-u.ac.jp
AF: Dept. of Civil and Earth Resources Engineering, Kyoto University, Yoshida-Honcho, Sakyo-ku, Kyoto, 606-8501 Japan
AU: Matsuoka, T
EM: matsuoka@electra.kumst.kyoto-u.ac.jp
AF: Dept. of Civil and Earth Resources Engineering, Kyoto University, Yoshida-Honcho, Sakyo-ku, Kyoto, 606-8501 Japan
AB: Discrete Element Method (DEM) approximates the geologic body as an assembly of particles, thus can appropriately simulate the brittle behaviour of the upper crust. We have applied the method to the indentation tectonics of Indian - Eurasian collision to examine the stress and velocity distributions of internal deformation of the Eurasian Plate. Since the method is a forward modelling technique, progressive development of strain and stress can be examined during the collision process. The results show that the velocity distributions and the stress fields of the particles, extracted for every short time interval during deformation, are quite unstable. This may be due to the brittle behaviour of the particle assembly corresponding to the upper crust, in which localisation of stress concentration and its release by faulting are clearly observed. In particular, shear stress is commonly concentrated along a broad shear band and is released by faulting, which causes a pair of large velocity anomaly in two opposite directions. When applied to real geology, the velocity distribution corresponds to GPS which shows overall continuous curvature from the Himalayan Mountains. This suggests that, although the surface deformation is characterised by faulting, such a large-scale tectonics is primarily controlled by ductile deformation of the lower crust and its substrates. The normal stress distribution of the simulation results demonstrated that the simplified tectonic model by Tapponnier (1982) has a strong boundary condition that may affect the experimental results, thus the model needs to be revised.
DE: 8100 TECTONOPHYSICS
DE: 8102 Continental contractional orogenic belts
DE: 8105 Continental margins and sedimentary basins
DE: 8107 Continental neotectonics
SC: Tectonophysics [T]
MN: 2003 Fall Meeting