|
ABSTRACT Shuang-Lien-Po fault is located on the Tao-Yuan
Terrace, just along the northern border of the Ping-Chen
anticline. Since the fault transverses several terrace surfaces
including the Yang-Mei surface, the Ta-Lun surface, and the
Chung-Li surface, it is considered quite young. The purpose of
this study is to detect the Shuang-Lien-Po fault and the
structures in its vicinity using the shallow seismic reflection
method. The results are also directed to understand the tectonic
movement which could cause the generation of this structure.
Seven long-range seismic lines are taken to cover the fault
traces. The obtained seismic profiles come out remarkably good,
which have identifiable seismic images even down to the depth of
600 meter. It is surprising to find that all structural layers
are very smooth, not exist a single track of structural offset.
The layers are bent to turn upward, but not broken, at the
suspected places of Shuang-Lien-Po fault. These seismic profiles
definitely deny the existence of this fault. In addition to the
fault detection, we also used eleven short-range seismic lines
arranged from the coast to the southern border of Ping-Chen
anticline to investigate the background tectonic reasoning which
creates the structure near the fault. After carefully reserving
the characteristics of each layer reflector, we are able to
correlate different layers on different seismic profiles and
obtain a gross picture of structural variation along a north-
south profile. Due to the blockage of Kuan-Yin Basement High
outside the northern coast, the layers are uplifted in the north
and decline gently toward the south. However, after passing the
Shuang-Lien-Po fault, the layers start to incline up and form
the Ping-Chen anticline. The place where the Shuang-Lien-Po
fault is situated is actually not a fault, but a depression
looked like a syncline. This study suggests to modify the name
of Shuang-Lien-Po fault to Shuang-Lien-Po syncline. (Keywords:
Shuang-Lien-Po fault, Taoyuan terrace, seismic reflection)
|