Deformation of Accretionary Wedges Based on 2D Distinct Element Modeling
Date Issued
2007
Date
2007
Author(s)
Wang, Fang-Lin
DOI
en-US
Abstract
This study explores the dominant role played by décollement basal friction μb on the deformation style or pattern of accretionary wedges. The Particle Flow Code in 2 Dimensions (PFC2D), a special implementation of distinct element method (DEM) using circular elements, is applied. In this study, basal friction of the décollement is designated to range from 0.05 to 0.9, and the interparticle friction is fixed as 0.5. Based on the modeling results with different basal frictions, two modes of deformation are clearly observed. For the low basal friction case (μb ≦ 0.3~0.4), the frontal accretion is prominent and is dominated by ‘pop-up’ structures at or near the toe of the wedge. For the high basal friction case (μb≧0.3~0.4), underthrusting is the principal feature during deformation throughout the wedge. We can observe not only the difference in the evolution but also the variation of thrust angle in the accretionary wedge during the experiments. Thrust angle varies from about 50° at μb=0.05 to about 10° at μb=0.9. Furthermore, we find a transition mode of deformation presents in μb=0.3~0.4 observed from growth rate of distance to deformation front, deformation zone, and uplift rate of maximum height. The range of this transition zone gives us another way to distinguish the critical value of the transit from low to high basal friction. Moreover, the surface slope changes from 3°±1° at μb=0.05 to 19°±1° at μb=0.9 and reaches stable at μb=0.35. Based on analyses on growth rate, uplift rate, and surface slope in the numerical models, geometric steady state of accretionary wedges is achieved when μb=0.3~0.4.
Subjects
增積岩體
離散元素法
二維顆粒流軟體(Particle Flow Code in 2 Dimensions: PFC2D)
滑脫面
滑脫面摩擦係數
Accretionary wedge
Distinct element method
Particle Flow Code in 2 Dimensions (PFC2D)
Decollement
Basal friction
Type
thesis
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