台灣及鄰近地區隱沒與碰撞作用─(子計畫六)台灣及鄰近地區之變形模式（Ⅱ）
Other Title
Deformation Mechanism of Collision Mountain Belt around
Taiwan (II)
Taiwan (II)
Date Issued
1999
Date
1999
Author(s)
DOI
882116M002018
Abstract
Geological modeling is a new way in geological
studies. By the help of physical modeling and
numerical modeling, we can understand the possible
models of the development of the kinematics and
dynamics evolution of structure. These studies try to
estimate the possibility of sandbox simulation
experiments in physical modeling; and try to analyze
the effect of boundary conditions and main controlling
factors in physical modeling. Furthermore, by using
physical modeling and three-dimensional numerical
modeling, we try to simulate the consequence of
geological settings, oblique convergence and basement
high in the inter-relationship between the development,
evolution and structure in the western Taiwan. We
hope that will help us understand more about the
regional tectonics of Taiwan.
By the simulation of sandbox behavior, there are some
conclusions: most models develop conjugate thrust
faults and pup-up structures; in most cases, the same
set of conjugate thrust faults developed earlier than the
backthrust faults. The modeling result is highly
affected by the friction coefficient of backstop; as the
friction coefficient reduced, the strain would
concentrate on the top part of the backstop and
increase along the ramp of the backstop. The greater
the angle of inclination of the backstop, the easier the
forward propagation of the strain. Reduction in the
angle of inclination results in the concentration of
strain near the toe front of the backstop, and a set of
pup-up structures could be found at the toe of the
backstop. As the friction coefficient of the base
reduced, the forward propagation of the strain
becomes more easily. Thought the competence of
materials would affect the displacement of the
propagation, it is not as important as the others factors.
This research aimed to realize the effect of the
basement high of western Taiwan during oblique
convergence. Results: Backstop mainly affects the
earlier stage of the oblique convergence; the shape of
the basement and the early stage structures formed by
the indent backstop controls the shape and
development of later stage structures. As a
consequence, forward propagation of the deformation
front occurred in the central western Taiwan, because
of the resistance at the front of the basement high, the
deformation front propagated slowly at the front of the
basement high. There is low resistance in the southern
Taiwan and the sediments there are thickened, the
deformation front moved forward. The above reasons
may explain the S-shaped deformation front at the
western Taiwan. Most thrust faults are forward-breaking
sequence and it develops later in the western
region. The formation of Tatu terrace, Bakua terrace,
west Hengchun terrace may be the result of thrust
faults; Pingtung valley, Taichung basin, Hengchun
plain may be piggy-back basins. And these results are
supported by the preliminary results of these
experiments. Sandbox physical modeling is very
useful in the research of the development and
evolution of geological structures, and it showed great
potential in this research. From the analysis of the
parameters of the three-dimensional numerical
modeling, we suggest that the interface friction angle
of the basement high should be smaller than 15°. The
existence of the basement high in the numerical
modeling results in the change in the direction of stress
field and strain field. Based on the nature of faults, we
suggest that the faults near basement ramp tend to
develop thrust faults and strike-slip faults would
develop at later stage. Since the strain energy
concentrated at the front of the West-Foothill near
Chiayi and Tainan, these areas may affect by
earthquakes.
Subjects
Geological modeling
physical
modeling
modeling
western Taiwan
earthquakes
tectonics
Publisher
臺北市：國立臺灣大學地質科學系暨研究所
Type
report
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