| dc.description.abstract | The Tainan Formation underneath the Southwestern Plain of Taiwan
is the best material for studying Holocene tectonics and Paleoearthquakes
in the region. This study collect drill logs, trench maps, C-14
age data and related study results, and also apply the magnetic
susceptibility measurement technique on several drill cores to help
stratigraphic correlation analysis. We perform geomorphologic analysis,
stratigraphic analysis and tectonic analysis and synthesize the results to
clarify the stratigraphy and tectonic history of the Tainan Formation in the
study area.
Results from stratigraphic analysis reveals, this study area has at
least deposited two sequences of sediments, which may be eustatic
change related. This study define the bottom of the Tainan Formation at
the bottom of the upper sequence, at where paleosol or weathering debris
is commonly found. This study select the Tainan well core to present the
standard column of the Tainan Formation. The C-14 age at the bottom is
about 18Ka. We follow Lin(1963) to define top of the Tainan Formation.
The C-14 age at the top is about 3Ka.
According to profile analysis, the dip angle of strata at lower part of
the Tainan Formation is steeper than that at upper part and top surface of
the Tainan Formation. We interpret this phenomenon as growth fold in the
study area. According to uplift rate calculation at different time planes, it
tend to increasing positive uplift rate at present highland area. At low
lands, like the Tsengwen-hsi river mouth and most coastal area, which
show continues subsidence. In the Kaohsiung area, it shows uplift around
18 Ka, and then become subsidence since about 6 Ka.
The distribution of the Tainan Formation is rather wide in
Southwestern Plain of Taiwan. We can recognize the Tainan Formation in
every core in the study area. According to related study, the Tainan
Formation may extend northward to south of the Choshuihsi alluvium fan,
and southeastward to west of Pingtung Plane. | en_US |