HR: 0800h
AN: T51B-0554    [Abstracts]
TI: The Effective Factors in the Deformation of Accretionary Wedges: Insight from Sandbox Experiments
AU: * Pan, C
EM: r95241313@ntu.edu.tw
AF: Insitute of Oceanography, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
AU: Lu, C
EM: chia@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
AU: Chiao, L
EM: chiao@ccms.ntu.edu.tw
AF: Insitute of Oceanography, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
AB: Sandbox experiments are therefore frequently used to model the upper crust deformation in convergent plate margins and similar compressional tectonic regimes following the critical-taper Coulomb wedge theory. Several parameters are known tp affect the observed deformation in the sandbox experiments as well as actual accretionary wedges. In this study, control on wedge deformation from varying basal friction, rigid base tilt angle values, and presence of decollement levels simulated by thin glass microbead layers, are investigated through 2- D sandbox experiments The results obtained through the particle image velocimetry(PIV) analyses are useful as compareing phenomena displayed in the physical models and numerical simulations. By applying PIV analysis, two deformation cycles of frontal growth in sequence can be seen: a simple shear zone and a inverted triangular zone. The simple shear zone will become the thrust, and the inverted triangular zone will become the pop-up structure. In our sandbox results, the high basal friction models have more apparent uplift. The pop-up structures are always in low basal friction models, and these can be observed in the wider structural spaces. The higher angle of rigid base has more underthrusting at the displacement fields in the both of high and low basal friction models. In the experiments of the glass microbeads layer below 2 cm of the surface, the imbricate thrusts nucleate and propagate above the microbeads layer, the underthusting developments below the microbeads layer. The different thickness of microbeads layer and the depth below the surface are something we intend to experiment within the future. These parameters are valuable to determine the actual accretionary wedge.
DE: 1744 Tectonophysics
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8015 Local crustal structure
DE: 8020 Mechanics, theory, and modeling
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting