經濟部
ABSTRACT
Our study proposes that the Hsiaokangshan fault could be a blind fault that was formed by a
mud intrusion and followed by lateral compression during orogeny. Activity of the
Hsiaokangshan fault is still unknown, to verify the structure and its evolution, further studies
in this area are needed as well.
1
Xiaogangshan fault：
The Xiaogangshan fault is located in the northwest of Xiaogangshan, Kaohsiung County, with
a north-south trend, and the northern end gradually turns to a northeast trend, with a total length
of about 8 kilometers, which may be a reverse fault (Lin Qiwen et al., 2000a; Sun, l964). Since
there is no clear geological evidence on the Xiaogangshan fault, it is temporarily classified as a
suspected active fault.
The identification of the Xiaogangshan fault is mainly based on the topography.
Sun (1964) determined from the aerial photo that the five-section eastern side rises an
d is arranged in a line-shaped fault small cliff, and speculates that it is caused by an
eastward-dipping reverse fault. Xu Tieliang and Zhang Xianqing (Hsu and Chang, 19
79) pointed out that the Xiaogangshan fault formed a fault line cliff between Xiaogan
gshan and Alian, and speculated that it was a reverse fault that may still be active.
Nowadays, the terrain of the fault cliff is no longer obvious due to the man-made da
mage to the terrain. Yang Guisan (1986) pointed out that these small cliffs are not c
ontinuous and less obvious. Due to the lack of surface outcrop evidence and the lack
of detailed geophysical exploration, Zhang Huizheng et al. (1998) classified the Xiao
gangshan fault as a suspected active fault.
The Xiaogangshan fault line and both sides drawn by Lin Qiwen et al. (2000a)
has no outcrops, and the degree of human development is relatively high. There is no
clear geological evidence, and further investigation is needed. Weng Qunping et al.
(1999) pointed out that the disturbance zone of the Xiaogangshan fault dislocation is
very obvious from the seismic survey results, but it shows the shape of a normal fau
lt, and believes that the Xiaogangshan fault should be a creeping fault with slow defo
rmation. Our team has carried out two shallow seismic survey lines at the southern e
nd of the Xiaogangshan fault, among which the signal quality of the survey line on t
he west side is excellent, while the signal quality of the section at the possible exten
sion position of the fault is poor, but the normal fault as mentioned above cannot be
seen. The long-term and short-term slip rates of the Xiaogangshan fault still need to
be further obtained.
2
The main structures around the Xiaogangshan fault are the Dagangshan anticline,
the Gutingkeng fault and the Zhongzhou anticline. The Zhongzhou anticline is NE tre
nding and is about 10 kilometers wide. CNPC carried out three wells on the shaft, a
nd the deep part was all mudstone in the Guting pit. This anticline structure has bee
n found from gravity, seismic data and downhole geology. Both Hsieh (1972) and Pa
n (1968) believed that it may be related to the structure of the mud-penetrating body.
Although the Dagangshan anticline is not seen in the CNPC 1/100,000th geologic
al map (Fig. 3.1), the internal report shows that it is an anticline and is named as th
e Dagangshan anticline. Xiaogangshan and Dagangshan are dominated by coral reefs,
and the highest coral reef height is about 300 meters, showing that the vertical uplift
is at least 300 meters. Since the Guting pit layer is the sedimentary environment of
the continental slope, the water depth can range from 1000 to 2000 meters. Therefore,
if the water depth of the Guting pit layer is 1000 meters, the vertical uplift of the
Dagangshan anticline will be at least 1300 meters.
Figure 3.2 shows the DTM numerical topography in the area of the Xiaogangshan fau
lt. From the numerical topography, it can be seen that there is a NE trending line on
the west side of the Dagangshan anticline. This line is roughly the location of the
Xiaogangshan fault in the past. The lower section in Figure 3.2 is the topographic se
ction of section AB in the above figure. In the section, the Zhongzhou anticline prese
nts a relatively gentle uplift on the terrain. In order to further analyze the terrain, we
cut two more linear terrain profiles, and we can see the cliff face of about 10 meters
in the terrain.
In 2007, the Geological Survey carried out a 200-meter-deep exploratory well on the
Xiaogangshan fault. Using the topographical features, the site was located at the upper
edge of the topographic cliff. The height difference between the two sides of the top
ographical cliff was about 4 meters. It is a loose modern alluvial layer with serious v
egetation and brownish-yellow color (Liu Yanqiu, 2007). Preliminary observations of t
he cores are all argillaceous even with shellfish fossils, and the phenomenon of shear
cracking can be seen at 98m. No clear evidence of regional fault activity was found
in the cores drilled, and no disturbed changes in the position of the strata were foun
d. The team also carried out new shallow seismic surveys, and cooperated with the e
xisting drilling and regional underground structures of the Geological Survey Institute.
Analysis of the subsurface structural characteristics of the Xiaogangshan fault.
3
Figure 3.1. Geological map of the area around the Xiaogangshan fault. Modified from
CNPC's 1/100,000 Tainan Geological Map (CNPC, 1989).
4
Figure 3.2. Numerical topographic map along the Xiaogangshan fault. The figure sho
ws the uplift of the Zhongzhou anticline and the alignment of the Xiaogangshan fault.
5
Figure 3.3, Figure A and Figure B are the topographical sections (in meters) of Secti
ons C and D in Figure 3.2, respectively.
(1) Regional underground structure analysis
Figure 3.4 shows the distribution of regional subsurface structural profiles used in this
study, the configuration of shallow seismic lines that have been implemented, and the
distribution of related drilling wells in the area of the Xiaogangshan fault. Regional
underground structures are mainly analyzed using the CNPC seismic profile, which is mainly
based on the coincidence of the midpoint of the survey lines AA' and BB' in Figure 3.5 and
the interpretation profile. The AA' section (Fig. 3.5) is located farther north, passing through
the Zhongzhou anticline, on the east side of the section and passing through the suspicious
topographic cliff face and the location of the Xiaogangshan fault mapped by past geology. In
6
the BB' section (Fig. 3.6), it can be seen that there is no reflected signal on the axis of the
Zhongzhou anticline, and the reflected signal appears on both sides of the axis. Interbedded
lithofacies of sand and shale，Therefore, a better reflected signal appears. Distant anticline
sediments can also be seen in the shallow formations on either side of the anticline, showing
a growth strategist as the folds developed (Fig. 3.5). The AA' section passes through the west
side of the Zhongzhou anticline and the west side of the Dagangshan anticline. The triangular
positions in Figure 3.6 are the fault line traces and topographic cliff traces drawn by the
geological survey. It can be seen from the seismic profile that there is no fault beneath the
fault line traced by the ground survey. Weng Qunping (2000) believed that the Xiaogangshan
fault is a normal fault dipping westward, but this possibility can be ruled out in this section.
As for the eastward dipping reverse fault, it cannot be ruled out due to the lack of reflection
signal identification.
Figure 3.4. Regional subsurface structural profile (yellow line) used in this project alo
ng the Xiaogangshan fault, the shallow seismic line configuration (blue line)
7
a
b
Figure 3.5. Image of line AA' (CNPC) (a) and interpretation profile (b), which passes
through the Zhongzhou anticline.
8
a
b
Figure 3.6. Image of survey line BB' (CNPC) (a) and interpretation section (b). This section
not only passes through the west side of the Zhongzhou anticline, but also passes
through the east side of the Xiaogangshan fault. The triangular positions in the figure
9
are the topographic cliff and the ground respectively. Adjust the drawn fault lines.
(2) Shallow seismic survey
In this study, a total of 3 shallow seismic survey lines were implemented along the
Xiaogangshan fault. 1) The survey line is 1,600 meters long and spans the topogra
phic cliff suspected to be the Xiaogangshan fault; 2. The survey line is 37 meters
higher than the southern edge of Alian Township Road (survey line 08P-HKSF-AL2), the survey line length is 733 meters 3. The survey was carried out on the north
ern section of the fault along the county road 13-1 higher (the survey line 08P-HK
SF-AL-3), and the length of the survey line was 475 meters. The configuration posi
tions of these three survey lines are shown in Figure 3.3 & Figure 3.7 respectively.
Figure 3.7. The relative location of survey lines 08P-HKSF-AL-1, 08P-HKSF-AL-2 and
08P-HKSF-AL-3 (solid blue line), and the red dotted line is the possible passage of the
Xiaogangshan fault.
10
1. Alian Line 1 of Xiaogangshan Fault (08P-HKSF-AL-1)
The survey line 08P-HKSF-AL-1 is the first survey line arranged for the Xiaogangshan
fault in the Alian area of the middle section of the fault. An obvious terrain cliff can be seen
on the road, and the terrain cliff is suspected to be related to the Xiaogangshan fault. The
survey line is located in Fu'an Village, Alian, along the county road 14-1, with a total section
length of 1,600 meters. Figure 3.8 shows the location of survey line 08P-HKSF-AL-1 on the
1/25,000 topographic map. The survey line is roughly northwest-southeast, and the height
difference between the southeast and northwest ends of the terrain along the line is about 17
meters. Figures 3.9a and b show the ground conditions looking westward and eastward along
the survey line 08P-HKSF-AL-1, respectively.
The survey line 08P-HKSF-AL-1 uses the JMS-MINI65 seismic source to advance from
west to east in a push method, and from the east end of the survey line to the west in a push
method, and uses a 96-channel seismometer to receive the earthquake. measurement signal.
The distance between the receiver groups of this survey line is 5 meters, the minimum close
distance is 5 meters, and the distance between the blasting points is 10 meters. The average
impact of each blasting point is about 40 times, and each receiver group uses three 40 Hz
receivers. The wave receivers are arranged in parallel, the wave receiver spacing is 1 meter,
and the average number of coincidences is 24. Table 3.1 shows the seismic parameters used
for the survey line 08P-HKSF-AL-1.
Figure 3.10a shows the records of 3 representative measuring points along the survey
line 08P-HKSF-AL-1. This survey line is located in a section with frequent traffic and the
noise interference is serious, and the bottom right in the record is the ground roll wave.
Although the filtered signal of the ground roll wave is not very significant in the recording of
a single measuring point, although the signal-to-noise ratio can be improved after processing,
only the reflected signal with a depth of more than 200 milliseconds can be clearly seen.
Figure 3.10b shows the filtered measurement point record, in which the low-frequency
ground roll has been roughly filtered out.
The basic data processing flow of this survey line is shown in Figure 1.9. After
data processing, the overlapping section of the Alian line 08P-HKSF-AL-1 with the
midpoint is shown in Figure 3.11a. It can be seen from the profile that the strata in
the western half of the section have good continuity, while the strata in the eastern h
alf only appear in the shallow part. Fig. 3.11b is the interpretation of profile 08P-HK
11
SF-AL-1, in conjunction with the interpretation of drilling data, the horizontal yellow
line is the base plate, and the base plate rises to the east, but at the east end of the
survey line, the base plate surface is too shallow to be seen from the profile out. T
he yellow line sloping eastward in the middle of the section is the junction of the m
udstone and the western strata, and the stratum to the west of the mudstone can still
be seen at a depth of 1 second. The blue signal explained below the base plate on
the east side of the profile is quite clear, and its frequency (about 50 Hz) is lower t
han the reflected signal (about 75 Hz) of the base plate surface, but since there is no
layered phenomenon in the mudstone in the base plate, it may be that the mudstone
is relatively fragmented It comes with saturated water. Since there is no water-bearin
g phenomenon in the well logs interpreted by Shanjiaoxia Well No. 1, the cause of t
he blue signal still needs to be further studied, but it should not be a stratum.
Comparing the profile and topography, it can be seen that the topographic cliffs
on the surface of the survey line are not caused by faults, and the front edge of the
underground fault may still be located to the west of the survey line, about line 19A
(see Figure 3.7). Figure 3.12 shows the coincidence velocity distribution of section 0
8P-HKSF-AL-1. The coincidence speed is first converted to the interval speed, and th
en used as the basis for the time profile to be converted to the depth.
Figure 3.13 shows the comparison between the measuring point record of section
08P-HKSF-AL-1 and the measuring point record of the west side of Line A of Tai
wan 19. In the record of the survey point of profile 08P-HKSF-AL-1, there is only a
signal for more than 0.2 seconds, but the signal of the survey point on the west sid
e of Line A of Taiwan 19 can reach 1 second. The two signals are completely differ
ent, and there is a great lithology. difference.
12
Figure 3.8. The location of the survey line 08P-HKSF-AL-1 in the 1/25,000 topograp
hic map (solid blue line), and the red dotted line is where the Xiaogangshan fault ma
y pass.
a
b
Figure 3.9. Land performance along the survey line 08P-HKSF-AL-1 to the northwest
(a) and to the southeast (b).
13
Table 3.1 Seismic parameters of the survey line 08P-HKSF-AL-1
Line name
08P-HKSF-AL-1
Fu'an Village, Alian To
Line location
wnship, Kaohsiung Count
epicenter
yJMS-mini 65
接收波道（個）
96
Receiver array spacing (m)
5
The number of receivers in each
3
group (pieces)
Individual spacing within each gro
1
up of receivers (m)
Type of receiver
40Hz vertical
Minimum close support distance
5
(m)
Maximum far support distance
505
(m)
Blasting point distance (m)
10
The number of shock sources (ti
40
mes)
Sampling interval (ms)
0.5
Recording time (sec)
1.024
Maximum number of coincidences
24
Total length of measuring line
1600
(m)
line direction
Northwest→Southeast
Line straightness
meander
14
a
b
Figure 3.10, a. Records of 3 representative measuring points along the survey line 08
P-HKSF-AL-1. There is frequent traffic along the survey line, and the reflecte
d signal is not easy to observe. b. The measuring point of the measuring line
08P-HKSF-AL-1 records the filtered result, in which the low frequency noise
15
has been roughly filtered out, but the reflected signal only appears for more
than 0.2 seconds。
16
a
Figure 3.11a, the sectional view of the same midpoint of the survey line 08P-HKSF-AL-1. The reflected signal can be seen at a dep
th of about 300 milliseconds in the profile。
17
b
Figure 3.11b, Explanation of Section 08P-HKSF-AL-1. The yellow line should be the base plate, and the blue signal is more likely t
o be the aquifer rather than the formation reflection。
18
Figure 3.12. Coincidence velocity distribution of section 08P-HKSF-AL-1。
Figure 3.13. The record of the measuring point on the east side of section 08P-HKSF
-AL-1 (there is a signal for more than 0.2 seconds) and the record of the me
asuring point west of the station 19 A line (the reflected signal can reach a
depth of 1 second) have a completely different performance。
19
2. Alian Line 2 of Xiaogangshan Fault (08P-HKSF-AL-2)
The survey line 08P-HKSF-AL-2 is the second survey line arranged for the southern
section of the Xiaogangshan fault in Fu'an Village. The survey line is located between
Dagang Mountain and Xiaogang Mountain. It is surveyed along the height of 37 Alian
Township Road. The total length of the survey line is 733 meters. The Xiaogangshan fault
may be formed by the mud-filled body. If its shape is like a salt dome, the survey line should
be like the survey line 08P-HKSF-AL-1, and the stratum can be clearly seen in the profile.
Figure 3.14 shows the location of survey line 08P-HKSF-AL-2 in the 1/25,000 topographic
map. The relative positions of lines 08P-HKSF-AL-2 and 08P-HKSF-AL-1 are shown in
Figure 3.8. The survey line generally runs east-west. The terrain along the line continues to
rise to the east, and the height difference between the west and northeast ends is about 14
meters. Figure 3.15a and b are divided into the situation along the survey line
08P-HKSF-AL-2 looking westward and looking eastward.
The survey line 08P-HKSF-AL-2 still uses the JMS-MINI65 impact source during the
survey. During the survey, the western section of the survey line is pushed forward from west
to east, and the eastern section of the survey line is changed from east to west. Moving
forward in a push manner, the seismic signals are all received by a 96-channel seismometer.
The distance between the receiver groups of the extension line of this survey line is 5 meters,
the minimum close support distance is 5 meters, and the distance between the blasting points
is 10 meters. Each blasting point hits an average of about 50 times, and each group of wave
receivers uses 3 receivers. The 40 Hz receivers are arranged in parallel, and the distance
between each receiver is 1 meter. The maximum number of coincidence sections is about 24
coincidences. Table 3.2 shows the seismic parameters used by the survey line
08P-HKSF-AL-2.
Figure 3.16a is a record diagram of three representative measuring points along the
survey line 08P-HKSF-AL-2. The reflected signal in the picture is difficult to see due to
frequent traffic. Figure 3.16b shows the filtered measurement point record. The energy of the
ground roll wave is obviously weakened, but the reflected signal is still very unclear.
Figure 3.17a shows the processed coinciding profile of the second line of Alian
(08P-HKSF-AL-2). The visible depth of the stratum is about 200 milliseconds, which is
consistent with the image on the east side of the line 08P-HKSF-AL-1. The basic data
processing flow of this survey line is shown in Figure 1.9. Figure 3.17b is a cross-sectional
20
interpretation of this survey line, and the yellow line is the base plate surface. This survey
line is similar to the image on the east side of survey line 08P-HKSF-AL-1. The base plate
signals gradually rise to the east, and low-frequency similar to water layers can also be seen.
It can be seen from this figure that the mud pouring body is not dome-shaped, and the
junction of mudstone and western strata should still be on the west side of the section. Figure
3.18 shows the coincidence velocity distribution of this section. The coincidence speed is first
converted to the interval speed, and then used as the basis for the time profile to be converted
to the depth.
Figure 3.14. The location of the survey line 08P-HKSF-AL-2 in the 1/25,000 topogra
phic map (solid blue line), and the red dotted line is where the Xiaogangshan fault
may pass.
a
b
圖3.15、測線08P-HKSF-AL-2往西(a)及往東望(b)之地表現況。
21
表 3.2 測線 08P-HKSF-AL-2 之震測施測參數表。
Line name
08P-HKSF-AL-2
Line location
高雄縣阿蓮鄉復安村
epicenter
JMS-mini 65
接收波道（個）
96
Receiver array spacing (m)
5
The number of receivers in each
3
group (pieces)
Individual spacing within each gro
1
up of receivers (m)
40Hz垂直式
Type of receiver
Minimum close support distance
5
(m)
Maximum far support distance
490
(m)
Blasting point distance (m)
10
The number of shock sources (ti
40~50
mes)
Sampling interval (ms)
0.5
Recording time (sec)
1.024
Maximum number of coincidences
24
Total length of measuring line
733
(m)
line direction
西→東
Line straightness
蜿蜒
22
a
b
Figure 3.16, a. Records of 3 representative measuring points along the survey line 08
P-HKSF-AL-2, the noise disturbance is serious in the picture. b. After filterin
g, the ground roll wave is obviously weakened, but the reflected signal is sti
ll not easy to observe。
23
W
a
Fig. 3.17a, Coincidence profile of the midpoint of Alian line 2 (08P-HKSF-AL-2) afte
r processing. The profile is visible to a depth of about 200 ms.
24
200
b
Figure 3.17b, Sectional interpretation of line 08P-HKSF-AL-2. The base plate graduall
y rises to the east, and low-frequency signals similar to water layers are also visible.
圖3.18、測線08P-HKSF-AL-2之重合速度分佈。
25
2. Alian Line 3 of Xiaogangshan Fault (08P-HKSF-AL-3)
In order to examine the behavior of the mudstone boundary extending to the north, the
survey line 08P-HKSF-AL-3 is the third survey line set up in the area of Fu'an Village in the
northern section of the Xiaogangshan fault. 475 meters. Figure 3.19 shows the location of
survey line 08P-HKSF-AL-3 in the 1/25,000 topographic map. The relative positions of the
survey lines 08P-HKSF-AL-3 and 08P-HKSF-AL-1 and 08P-HKSF-AL-2 are shown in
Figure 3.8. The survey line is generally northwest-southeast. The terrain along the line
continues to rise to the east, and the height difference between the northwest and southeast
endpoints is about 14 meters. Figure 3.20a and b are divided into the situation along the
survey line 08P-HKSF-AL-3 looking westward and looking eastward.
The survey line 08P-HKSF-AL-3 used the JMS-MINI65 impact source during the
survey, and moved from west to east in a propulsive manner during the survey. The seismic
signals were all received by a 95-channel seismometer. The distance between the receivers on
the extension line of this survey line is 5 meters, and the minimum close distance is 5 meters.
The distance between the blasting points of the first 10 strokes is 10 meters, and the distance
between the blasting points of the last 22 strokes is 20 meters. The explosion points hit about
20 times on average, and each group of receivers uses three 40 Hz receivers arranged in
parallel, and the distance between each receiver is 1 meter. The maximum number of
coincidence sections is about 24 coincidences. Table 3.3 shows the seismic parameters used
by the survey line 08P-HKSF-AL-3.
Figure 3.21a is a record diagram of three representative measuring points along the s
urvey line 08P-HKSF-AL-3. The reflected signal in the picture is difficult to see due
to frequent traffic. Figure 3.21b shows the filtered measurement point record. The ene
rgy of the ground roll is significantly reduced, but the reflected signal is still very un
clear, and there are many noises from the lateral direction.
The basic data processing flow of this survey line is shown in Figure 1.9. The proce
ssed coinciding profile of Alian Line 3 (08P-HKSF-AL-3) is shown in Figure 3.22a,
with a visible depth of about 120 milliseconds, and is only visible on the west side
of the profile. Figure 3.22b explains the section of this survey line. The yellow line i
s the base plate surface. The base plate surface of this section is shallow and gradual
ly rises to the east. The boundary between mudstone and western strata is still on the
west side of this section. Figure 3.23 shows the coincidence velocity distribution of t
his section. The coincidence speed is first converted to the interval speed, and then u
sed as the basis for the time profile to be converted to the depth.
26
Figure 3.19. The location of the survey line 08P-HKSF-AL-3 in the 1/25,000 topogra
phic map (solid blue line), and the red dotted line is where the Xiaogangshan fault
may pass.
27
a
b
Figure 3.20. The performance of the survey line 08P-HKSF-AL-3 looking west (a) an
d looking east (b).
表 3.3 測線 08P-HKSF-AL-3 之震測施測參數表。
測線名稱
08P-HKSF-AL-3
測線位置
高雄縣阿蓮鄉復安村
震源
JMS-mini 65
接收波道（個）
95
受波器陣列間距（m）
5
每組受波器個數（個）
3
每組受波器內個別間距（m）
1
受波器種類
40Hz垂直式
最小近支距（m）
5
最大遠支距（m）
475
炸點間距（m）
10、20
震源撞擊次數（次）
20
取樣間隔（ms）
0.5
28
記錄時間（sec）
1.024
最大重合數
24
測線總長（m）
475
測線走向
西北→東南
測線曲直性
蜿蜒
29
a
b
Figure 3.21, a. Records NW
of 3 representative measuring points along the measuring line
08P-HKSF-AL-3, the noise in the picture is seriously disturbed, and the reflected sig
nal is unclear. b. The ground roll wave is obviously weakened after filtering, but the
reflected signal is still not easy to observe.
30
200m
a
Fig. 3.22a, Coincidence profile of the midpoint of Alian line 3 (08P-HKSF-AL-3) afte
r processing. The profile is visible to a depth of about 200 ms.
31
b
Figure 3.22b, Sectional interpretation of line 08P-HKSF-AL-3. There is no sign of a f
ault.
Figure 3.23. Coincidence velocity distribution of survey line 08P-HKSF-AL-3.
32
(3) Surface and underground geological survey
Based on deep seismic profile, shallow seismic and gravity data, and geological identi
fication of Well No. 1 at the foot of the mountain. This study preliminarily believes
that the line shape of the Xiaogangshan fault is caused by the fold deformation of th
e underlying mud intrusion, which intrudes into the Dagangshan anticline, and the ver
tical uplift of this anticline is at least 1,300 meters.
1. Well logging of No. 1 well at the foot of the mountain
The well is located about 200 meters on the east side of the terrain cliff, and th
e height difference between the two sides of the terrain cliff is about 4 meters. The
surface composition is loose modern alluvial layer, and the vegetation is serious (Liu
Yanqiu, 2008). Figure 3.24 shows the drilling location of Well No. 1 at the foot of t
he mountain. The lithology of the formation is roughly as shown in Table 3.4, and t
he detailed well log is listed in Appendix 5. The 0-36 meters in the core are Holoce
ne marine strata, with a low dip angle and unconformity on the underlying Guting pit
layer. The Guting pit layer is inclined at a high angle, about 50-70 degrees. There a
re many small faults developed in the Gutingkeng layer, and it can be found in the
well log that the dip angle of the fault is roughly between 20 and 90 degrees. Figure
s 3.25 to 3.27 depict partial fault zones, similar to those widely distributed in cores.
In Figure 3.25, A is the core at 16.8 meters, and it can be seen that the formation is
nearly horizontal. B is the reverse fault near 37.3 meters, black fault gouge is comm
only developed in this core, C is the conjugated reverse fault, and Figure D is the re
verse fault near 46 meters, with black fault mud. A in Figure 3.26 is a high-angle no
rmal fault at 137 meters. B is a high-angle normal fault at 163 meters. C is the conj
ugate low-angle reverse fault, and the black fault gouge is cut by another set of fault
s. D is the 184.2-meter conjugate reverse fault. A and B in Figure 3.27 are high-angl
e normal faults at 189 meters. C is the high-angle fault at 197 meters. The visible la
yers in Figure D are nearly vertical and present a flow-like structure. The core record
s show that compressive structures are dominant at low to medium and high angles,
and the near-vertical faults are roughly normal faults, showing that the maximum prin
cipal stress is in the vertical direction.
33
depth
lithology
level
0-24 meter
Well panned sand lay 0-5
fracture surface
er with limestone gra
vel and shell fragmen
ts
20-30 meter
Mainly a mud layer c 0-5
ontaining carbonaceou
s and shell debris
33.6-200 meter
Guting pit mudstone
50-70
20-90 degrees, the rupture s
urface is mainly the sliding
shear plane along the layer
and the high-angle fault
表3.4 山腳下1號井之岩芯岩性
34
Figure 3.24. Drilling position map of Shanjiaoxia Well No. 1 (modified from Liu Yan
qiu, 2008).
35
圖3.25、Ａ為山腳下一號井16.8公尺處，地層近水平，Ｂ為37.3公尺處斷層，發育黑色
斷層。C為37.4 公尺處斷層，斷層為共軛的高角度逆斷層。D為36公尺處的逆
36
斷層，發育黑色斷層泥。
圖3.26、A為山腳下一號井137公尺處高角度正斷層。B為163公尺處高角度正斷層。C為
37
共軛低角度逆斷層，黑色斷層泥受另一組斷層截切。D為184.2公尺的共軛逆斷
層。
38
圖3.27、A與B為山腳下一號井189公尺處高角度正斷層。C為197公尺高角度斷層。D圖
中可見層裡近垂直，並呈現類似流動構造。
39
2. Thickness of Quaternary sediments or overlying soil on the hanging wall of Xiao
gangshan fault, as well as the thickness and interface of each layer
From the core data of Shanjiao No. 1 Well, it can be seen that the Holocene marin
e strata from 0 to 36 meters, with a low dip angle, are not integrated on the under
lying Guting pit layer, and all below 36 meters are the Guting pit layer. According
to the drilling data of Professor Chen Wenshan, the shallow sediments gradually de
epened westward from the No. 1 well at the foot of the mountain, and the thicknes
s can reach more than 70 meters.
(4) Dynamic analysis of faults
Since the Guting pit layer was deposited on the continental slope with a water
depth of nearly 1,000-2,000 meters, the vertical uplift of this Dagangshan anticline
is at least about 1,300 meters. Xiaogangshan develops linearly on the west edge of
the Dagangshan anticline, and the limestone on the surface covers the mudstone of
Gutingkeng in the form of an angular unconformity. Downhole records show that t
he dip angle of the mudstone in Gutingkeng on the west flank of the anticline can
reach 50°-70°. Although the east flank of the anticline lacks seismic data, it has a
high anomalous gravity gradient (Hsieh, 1972), so it is inferred that the eastern fla
nk of the anticline should also be a high-angle sloping formation, and the tight inte
r flank angle is one of the characteristics of typical detachment folds or mud-penetr
ating structures. The gravity data in Figure 3.28 shows that there is a small-scale gr
avity high area under the Dagangshan anticline, and the size of this high area is si
milar to the distribution range of the Dagangshan and Xiaogangshan limestones (Fig
ure 3.28). In addition, it can also be clearly seen in the seismic section that in the ax
is of the Dagangshan anticline, the structure of the mud infiltrating body cutting the s
urrounding rock layers. However, according to the core records, in addition to vertical
flow structures in mudstone, there are also shear structures generated by horizontal c
ompression. Therefore, the Dagangshan anticline is not a simple mud penetration struc
ture, but may be a mud penetration structure accompanied by slipping folds. As for t
he depth of the detachment surface, according to the drilling data at the Zhongzhou a
nticline, the depth of the detachment surface should be below 4,000 meters. We specu
late that the detachment surface may be located at the junction of the Gutingkeng lay
er and the Wushan layer, because this is the place where the lithological contrast is t
40
he greatest, and it may also be the place where the strength contrast of the rock laye
rs is the greatest, and the depth may be about 5,000 meters. Since the flow behavior
of mudstone is affected by many local factors, it is difficult to quantitatively explain
the structures it forms with simple numerical methods. However, we can qualitatively
speculate that in the later stage of the deposition of the Guting pit layer, the mud pe
netration caused the areas including the Tainan platform, Zhongzhou, and the Dagangs
han anticline to uplift upward. Long-term erosion of the protruding terrain resulted in
the absence of the upper Guting pit layer, and then coral reef limestone was re-depo
sited on this eroded surface; the subsequent orogeny caused slip-off folds in the Gutin
g pit layer, and the fold axis was along the earlier ridges. The mud through-body de
veloped and finally formed today's structure, and its possible tectonic evolution is sho
wn below.
Figure 3.29 shows the terrane structure from southwestern Taiwan to the sea, in
which the sedimentary environment south of Zuozhen gradually changed from a shed
rift to a continental slope to abyss. Because this area is located on the front edge of
the orogenic belt, the sediments were largely supplied by the Central Mountains, whi
ch accumulated huge thickness of Gutingkeng mudstone. Under the rapid deposition, t
he concomitant compaction resulted in the inability of water to be discharged quickly
and was subjected to horizontal compressive stress to form a high-pressure environm
ent, which also led to the formation of mud penetrations. From the tectonic map fro
m the southwest to the sea in Figure 3.29, it can be seen that the present continental
slope is already in the sea off Kaohsiung (Chiu et al, 2006).
Figure 3.30 shows the distribution area of the mud infiltrate in the open sea of Kaoh
siung today (Chiu et al., 2006). The former southwest was also in the same environm
ent, with many mud penetrations. Figure 3.31 is a schematic diagram of the develop
ment of mud infiltrates and coral reefs. The mud penetrations developed in the accreti
onary wedges are located in a submerged environment, so these mud penetrations and
their overlying strata turn into folds and continue to increase their amplitudes. Becau
se the development location is in a tropical environment, coral reefs begin to develop
when the mud penetrations grow to the water level. Because coral reefs are less pro
ne to weathering than the hard caprock, when the folds and mud penetrations continu
e to interact and develop around the mud penetrations at the same time Reverse fault,
thus gradually uplifting the coral reef to form the present-day Okayama limestone.
41
Fig. 3.28. Gravity anomaly map along the Xiaogangshan fault area (Hsieh, 1972). It can be
seen that the axis of the anticline shows a high gravity area. There is a small-scale gravity
high area under the Dagangshan anticline.
42
Figure 3.29. Submarine topography and tectonic morphology of the sea off southweste
rn Taiwan. The sea off Kaohsiung is an accretive-nary wedge.
43
Fig. 3.30. Location map of present-day mud intrusions in the sea off southwestern Tai
wan. (Chiu et al., 2006).
44
Figure 3.31. Schematic diagram of the development of mud infiltrates and coral reefs.
A: In the subduction environment and orogenic belt environment, huge thick sedimen
ts were deposited, and mud intrusions were formed due to the high-pressure environm
ent caused by rapid deposition and horizontal compressive stress. Figure B shows that
this mud penetration is affected by horizontal compressive stress accompanied by fol
ds and reverse faults. When the mud penetration develops to the offshore surface, cor
al reefs begin to develop.
45
(5) Section Essentials
In the deep structural section, it can be seen that there is no reflected signal at the a
xis of the Zhongzhou anticline, and the reflected signal appears on both sides of the
axis. This is mainly because the axis is the mudstone layer of the Gutingkeng, and th
e two sides are interbedded lithofacies of sand and shale. Therefore, a better reflected
signal appears. Xiaogangshan develops linearly on the west edge of the Dagangshan a
nticline, and the limestone on the surface covers the mudstone of Gutingkeng in the f
orm of an angular unconformity. The formation of the Dagangshan anticline may be f
ormed by the folds accompanied by the mud penetration, and the seismic profile may
also have image characteristics similar to the Zhongzhou anticline.
In the profile of the shallow seismic survey line 08P-HKSF-AL-1, it can be seen
that the strata in the western half of the section have good stratigraphic continuity,
while the strata in the eastern half only appear in the shallow part. In the profile, the
base plate deepens from east to west, and the mudstone and the western strata meet
with a boundary line that slopes toward the east, and the depth of the western stratu
m can reach 1 second. The image of section 08P-HKSF-AL-2 is consistent with the i
mage of the east side of survey line 08P-HKSF-AL-1, and the base plate gradually ri
ses to the east. The profile of line 08P-HKSF-AL-3 has the same characteristics.
In the early stage of the formation of the Dagangshan anticline, it may be that t
he muddy sediments were affected by the compaction and dehydration of the accretio
nary wedge, and the water pressure in the local area increased, which triggered the m
ud penetration, resulting in the uplift of the Dagangshan anticline. Later, erosion occu
rred at the top of the anticline, resulting in the absence of the upper Guting pit layer
and the formation of coral reef rock masses on it. Later orogeny formed slip-off fol
ds here, expanded the amplitude of anticline folds, and created compressional shear zo
nes in the mud penetrations. The linear cliff of Xiaogangshan is the topographic featu
re developed at the western edge of the mud penetration.
Figure 3.32 shows the structural section across both sides of the Xiaogangshan Blind
Fault. The red inverted triangle in the figure is the suspected location of the Xiaogan
gshan fault. This study considers the Xiaogangshan fault to be a blind fault, formed b
y lateral compression after the penetration of mud. The stratum on the west side of t
he Gutingkeng mudstone in the section is six double layers, the upper layer is covere
d with modern alluvial layers, and the thickness gradually decreases from about 180
meters in the west to the east.
46
Figure 3.32. Structural section across both sides of the Xiaogangshan Blind Fault. The red
inverted triangle in the figure is the suspected location of the Xiaogangshan fault. This study
considers the Xiaogangshan fault to be a blind fault, formed by lateral compression after the
penetration of mud. The stratum on the west side of the Gutingkeng mudstone in the section
is six double layers, the upper layer is covered with modern alluvial layers, and the thickness
gradually decreases from about 180 meters in the west to the east.
Discussion and Conclusion
The shallow part of the Xiaogangshan fault is modern sediments, which are in
unconformity contact with the underlying Gutingkeng layer. The internal variation of the
Gutingkeng layer follows many faults. Based on the analysis of regional subsurface structures,
shallow seismic data and downhole data, we believe that the Xiaogangshan fault is more
likely to be caused by mud penetration and folding (Fig. 3.31).
From the profile of the shallow seismic survey line 08P-HKSF-AL-1 of the
Xiaogangshan fault (Fig. 3.11), it can be seen that the stratigraphic continuity of the western
half of the section located to the west of Line A of Taiwan 19 is good, while the eastern half
of the section has good stratigraphic continuity. The strata appear only in the shallow part. In
the section in Figure 3.11, the base plate deepens from east to west, and the Gutingkeng
mudstone and the six double layers in the west meet at an eastward-dipping interface, which
is the Xiaogangshan blind fault deduced in this paper. Strata in the western part of the fault
are visible to a depth of up to 1 second. The image of the seismic profile 08P-HKSF-AL-2
(Fig. 3.17) is consistent with the image of the east side of the survey line 08P-HKSF-AL-1
(Fig. 3.11), and the base plate gradually rises to the east. The profile of the survey line
08P-HKSF-AL-3 (Fig. 3.22) also has the same characteristics as the above two profiles.
47
Well No. 1 at the foot of the Xiaogangshan fault was drilled on the eastern terrain cliff
along the shallow seismic profile 08P-HKSF-AL-1 (as shown in Figures 3.7 and 3.11). The
Holocene marine strata in the core are unconformable on the underlying Gutingkeng
mudstone at 36 meters. The Guting pit layer is inclined at a high angle, with an angle of about
50-70 degrees, and many small faults with a dip angle of 20-90 degrees are developed.
normal fault. Chen Wenshan et al. (2008) also conducted 3 geological exploration wells along
the seismic profile 08P-HKSF-AL-1, namely Wells 1, 2 and 3 in Xiaogangshan. The well
logs of these four wells are plotted on the seismic profile as shown in Fig. 4.3, and Fig. 4.3a
is an enlarged view of the central area of the square in Fig. 4.3b. The interpretation of the
unconformity in the seismic profile is drawn by integrating the data from these four wells.
Figure 3.32 shows the structural section across the Xiaogangshan blind fault deduced in
this paper, and its tectonic evolution relationship is shown in Figure 3.31. In the early stage of
the formation of the Dagangshan anticline, it may be that the muddy sediments were affected
by the compaction and dehydration of the accretionary wedge, and the water pressure in the
local area increased, which triggered the mud penetration, resulting in the uplift of the
Dagangshan anticline. Later, erosion occurred at the top of the anticline, resulting in the
absence of the upper Guting pit layer and the formation of coral reef rock masses on it. Later
orogeny formed slip-off folds here, expanded the amplitude of anticline folds, and created
compressional shear zones in the mud penetrations. The linear cliff of Xiaogangshan may be
the topographic feature developed at the western edge of the mud penetration.
Chen Wenshan et al. (2008) believed that the Xiaogangshan fault is more likely to be a
wide fault zone composed of multiple branches or dense shear zones in the shallow
lithosphere. Deformation, construction is explained as shown in Figure 4.4. The structure
explained by Chen Wenshan et al. (2008) and the structure explained in this study both
believe that the Xiaogangshan fault is a reverse blind fault, and the fault tip does not cut
through to the surface, but there are also differences in the underground structure and its
evolution, which may be related to drilling the data is still insufficient and related to the
imaging interpretation of the mudstone area in the seismic profile.
This study believes that the topographic cliffs of Xiaogangshan are more likely to be
related to mud penetration and slip-off folds. However, due to the lack of observational data,
and the seismic activity in this area is not significant (Figure 4.5), the activity of the
Xiaogangshan structure at present is not clear. Long-term leveling and latitude and longitude
measurements are needed to analyze the influence of the vertical movement of the mud
48
penetration and the horizontal extrusion of the slipping folds, so as to re-evaluate the
correctness of the structural interpretation of this study. In order to further clarify the
Xiaogangshan blind fault, it is also suggested that a deep well should be drilled at the edge of
the mud penetration in the future to determine the fault location. If the dating data is added,
the tectonic evolution history of this area should be more clearly understood.
49
a
b
圖4.1、六重溪1號與2號井與白河3、4與5號井（陳文山等，2008）於震測剖面08P-MCL
F-BH-1上之相對位置與深度。圖4.1a為圖4.1b中紅色匡線部分之放大圖，測線08
P-MCLF-BH-1的位置則見於圖1.5。
50
W
E
a
W
E
b
圖4.2、木屐寮線形與六甲斷層一帶的震央與震源分佈圖。a、木屐寮線形與六甲斷層一
帶的震央分佈。圖4.2b、木屐寮線形與六甲斷層一帶的震源分布。
51
a
b
Figure 4.3. The relative positions and depths of Well 1 at the foot of the mountain and Wells
1, 2 and 3 in Xiaogangshan (Chen Wenshan et al., 2008) on the seismic profile
08P-HKSF-AL-1. Figure 4.3a is an enlarged view of the red line in Figure 4.3b, and the
location of the survey line 08P-HKS-AL-1 is shown in Figure 3.7. The blue interpretation
52
line seems to be less related to the strata, as shown by the seismic wave bandwidth and the
core of the No. 1 well at the foot of the mountain.
Figure 4.4. Xiaogangshan structural interpretation and seismic profile 08P-HKSF-AL-1
by Chen Wenshan et al. (2008). The shallow rock plate is a wide fault zone compose
d of multiple branches or dense shear zones. The fault tip does not penetrate to the s
urface and causes unequal deformation of the overlying loose sedimentary layer.
W
E
Figure 4.5. Distribution map of earthquake epicenters around Da and Xiaogangshan.
53
附錄 1、六重溪 1 號井井錄
54
55
56
57
附錄2、六重溪2號井井錄
58
59
附錄3、池口1號井井錄
60
61
62
63
64
附錄4、池口2號井井錄
65
66
67
附錄5、山腳下1號井井錄（岩層位態修正自劉彥求，2008；斷層面位態本研究單獨分析)
68
69
70
71