Cruise Report
R/V Hakuho-maru KH05-1-3 cruise
Evolution of the southern tipof the Parece Vela Basin−4000

June 15, 2005 to June 27, 2005
(Guam to Guam)

10
136

9

135

Co-chief scientists:
Kyoko Okino and Yasuhiko Ohara

Contents
Onboard participants list………. 2

Acknowledgement………. 5

Confidentiality………. 5

Summary………. 6

1

Background………. 72

Objectives of the cruise………. 93

Summary of Operations……….12

4

Explanatory notes and Preliminary Results
4.1 Bathymetry survey……….15
4.2 Gravity survey……….22
4.3 Magnetic survey……….27
4.4 Multichannel seismic reflection survey
4.5 Dredging……….395

Future Works

References……….49……….51

Appendices
Appendix A: Sound velocity table
Appendix B: List of SeaBeam navigation editing
Appendix C: Dredge logs
Selected scenes from KH05-1-3……….32

Onboard Participants List
Science
OKINO, Kyoko
Co-chief scientist
Ocean Research Institute, University of Tokyo
OHARA, Yasuhiko
Co-chief scientist
Hydrographic and Oceanographic Department of Japan
FUJIWARA, Toshiya
Japan Agency for Marine-Earth Science and Technology
LEE, Sang-Mook
Seoul National University
NAKAMURA, Yasuyuki
Ocean Research Institute, University of TokyoWU, Shiguo
Institute of Geophysics, Chinese Academy of Science
KOIZUMI, Kinichiro
Ocean Research Institute, University of Tokyo
YANG, Yaomin
Institute of Geophysics, Chinese Academy of Science
KIM, Yoon-Mi
Seoul National University
HARIGANE, Yumiko
Graduate School of Science and Engineering, Shizuoka
University
INOUE, Hiroyuki
Ocean Research Institute, University of TokyoWATANABE, Mizuki
Ocean Research Institute, University of Tokyo
SATO, Taichi
Ocean Research Institute, University of Tokyo
Technical Support
ISHIGAKI, Hideo
Ocean Research Institute, University of Tokyo
YOKOGAWA, Shin’ichiro
Marine Works Japan, Ltd.

2-4

Acknowledgement
We are grateful to Captain Fujita and the crew of R/V Hakuho-maru for theirprofessional skills to make this program successful. We also thank peoples in the Officefor Cruise coordination in Ocean Research Institute and peoples in the Research
Support Department of JAMSTEC for their on land logistical support to the cruise. Dr.
Teruaki Ishii kindly provided his dredge gears.

Confidentiality
Data and samples obtained during this cruise, most of which are described in this report,
should be treated as carefully as possible, in order to protect the priority of the cruise
participants.
Confidential and publication policies are as follows:(1) The participants aboard the KH05-1-3 cruise agreed the future study plan listed in
the section 5.
Those appeared in the lists have the priority for each study topics.
(2) No one other than the cruise participants or those listed in the future study plan can
submit papers or give oral (or poster) presentations using any data and/or samples ofthis cruise within 24 monthafter the completion of the cruise (June 25, 2007).
(3) Any questions on the data and samples of this cruise, or on the future study plans
must be forwarded to the co chief scientists.

5

Summary
The KH05-1-3 cruise aboard the R/V Hakuho-maru (JAMSTEC) were planned to reveal
the evolution history of the southern Parece Vela Basin and the structure of the Yap
trench-arc system. The ship left Guam on June 15, 2005 and returned to Guam on June27, 2005. We successfully conducted the extensive geophysical mapping in the southern
tip of the basin, long across-trench multi-channel reflection survey and two dredge
hauls.
The highlights of our results are summarized as follows:
1. The southern tip of the Parece Vela Basin has been mapped using state-of-the-art
instruments for the first time. The southward propagator tip of the Parece Vela Basinspreading center was discovered. The seismic profile from the Caroline Ridge to thebasin was acquired.
2. The western part of the survey area is characterized by “curved” deeps and robust
magmatism. The kinematics of the enigmatic “curved” structure remains unsolved
but it may be related to the rotational deformation associated with continuous rift
propagation and fracture zones. Dredging on the foot of one of the curved deeps
recovered some rock samples.

61. Background
Written by Kyoko Okino and Yasuhiko Ohara
1.1 Evolution of the Philippine Sea and the Parece Vela Basin
The Parece Vela Basin (PVB) is an extinct backarc basin behind the Mariana arc-trenchsystem (Fig. 1). The basin was formed in the Miocene by rifting of, and later backarc
spreading between the Kyushu-Palau Ridge and the West Mariana Ridge. The evolutionof the basin consists of at least two stages, 1) east-west spreading and 2) NE-SW
spreading [Okino et al., 1998; Okino et al., 1999](Fig. 2). In the first stage, spreading
propagated toward the north in the northern part of the basin, where several propagatortips with associated pseudo-faults are observed. East-west spreading continued from 26
Ma to 19/20 Ma and the spreading half-rate is estimated at 44mm/yr. The spreading
direction changed from E-W to NE-SW around 19/20 Ma, similar to the directionalchange of the Shikoku Basin opening. The ridge axis was highly segmented in thissecond stage, and prominent fracture zones developed. The spreading rate during NESW spreading has not yet been determined due to low magnetic anomaly amplitude andpoor data coverage, however we tentatively identified magnetic lineations and estimatedthe spreading half-rate at 30-35mm/yr. Based on the identification, spreading ceasedaround 11~12 Ma, about three million years after the cessation of the Shikoku Basin
opening. The Ar40-Ar39 age dating of a basalt sample dredged from the rift zone also
indicates 10~11 Ma. The extinct spreading center remains preserved as a row ofdepressions deeper than 6500 m, named the Parece Vela Rift (PVR).
Contrary to the previously studied northern PVB, the southern PVB remains almost
unmapped. The spindle-shape of the basin may indicate that the initial rifting andspreading propagated toward south in the southern part of the basin, however we haveno data directly indicating the ridge propagation.
1.2 Tectonic setting of the southern tip of the PVB and the Yap Trench
The southern tip of the PVB shows unique tectonic setting and geometry. The main partof the basin has developed between the Kyushu-Palau Ridge and the West Mariana
Ridge, on the other hand the southern tip of the basin is now located between thesouthern Kyushu-Palau Ridge and the Yap Trench. The southwestern tip of the Mariana
Trench trends nearly E-W toward a junction with the northern Yap Trench, where two
trenches form an acute cusp. It seems strange that the southern tip of the PVR (remnant
spreading axis) morphologically continues to the Yap Trench. The southern end of the
PVR is the North Yap Escarpment, a ~1500 m high escarpment extending N20E
parallel to the PVR fracture zones. The Yap Trench constitutes a link between the
Mariana Trench and the Palau Trench, where the Caroline Plate and Philippine Sea Plateconverge. The convergent rate is very slow, 0-6 mm/yr [Seno et al., 1993]. The
seismicity along the trench is markedly low with no evidence of a Wadati-Benioff zone
[Sato et al., 1997]. The arc including the Yap Island is characterized with the proximityof arc and trench (~50km) and with the absence of forearc. The arc consists primarily of
metamorphic rocks and lacks active volcanism [Hawkins and Batiza, 1977; Shiraki,

71971]. These facts cast some doubts on the ongoing subduction along the Yap trench-arc
system at present. Submersible dives were conducted and it was found that the gabbroic
rocks were exposed on the landward trench slope shallower than the 6000 m [Fujioka etal., 1996].
The seafloor east of the Yap Trench is characterized with the Caroline Ridge, a large
topographic high formed in the late Oligocene. The Caroline Ridge is divided into twoby the Sorol Trough trending WNW-ESE. The northern wing of the Caroline Ridge
collides with the Yap Trench at 1030N where the trench is deepest, whereas the Yap
Island lies in a NNW extension of the Sorol Trough. The style of lithosphericdeformation by the collision changes at the Sorol Trough; the extensional features arefound on the arc and slab to the north, on the other hand the compressional deformation
is dominant to the south [Lee, 2004].
McCabe and Uyeda [1983] suggested that the Caroline Ridge collided with the Yap
Trench in early Miocene, and that the collision made the volcanic activity in the Yap Arc
stop. [Fujiwara et al., 2000] compiled the bathymetry and gravity along the Yap Trencharea and proposed a scenario of tectonic evolution as follows (Fig. 3); 1) The Caroline
Ridge collided with the Yap Trench at ~25 Ma, however the subduction continues atvery low rate. The cessation of volcanism at the yap Arc was contemporaneous with thecollision. 2) The frontal part of the trench was removed by the subduction erosion,
causing the westward migration of the trench. 3) Lower crustal sections became
exposed on the arc-ward trench slope by overthursting. [Kobayashi, 2004] also
attempted to explain unique morphological and geological characteristics of this region
using a simple hydrodynamic model.
1.3 Lithospheric compositions of the PVB and Yap arc system
No systematic rock sampling had been done in the PVB since DSDP Leg 59 [Kroenke
and Scott, 1980] until KR03-1 by R/V Kairei. During the KR03-1, mantle peridotite andgabbros were recovered from the surface of the Godzilla Mullion and other corecomplexes. Plagiogranites associated with mantle peridotites were also recovered fromthe Godzilla Mullion surface, suggesting small amount of melts were highly
fractionated in this melt-starved spreading. [Ohara et al., 2003a] described detailed
petrological data of serpentinized peridotite and gabbro from the PVR for the first time,and revealed small degree of mantle melting beneath the basin. Peridotites are exposedat mid-points of the northern segments, in addition to the Godzilla Mullion surface. Thisis anomalous, because segment mid-points are generally considered to be the mostmagmatically robust part of an entire ridge system, with the highest degree of mantle
melting [Lin et al., 1990]. The most notable characteristic of PVR peridotites is thepresence of fertile peridotite; spinel Cr # (= Cr/Cr+Al ratio) ~ 0.17, with smaller Cr #indicating a lower degree of depletion of source mantle peridotite [Dick and Bullen,
1984]. Fertile peridotites indicate only a minor melting (~ 4 % near-fractional melting
of a MORB-type mantle). Recent two submersible dives at the Shinkai Deep in thesouthern PVR confirmed that the Moho is exposed at ~ 6180 m depth at the deep8

Geochemical studies of peridotites and volcanics from the Yap Trench and the North
Yap Escarpment shows that the Yap Trench peridotites are highly depleted suductionrelated mantle residues and the NYE volcanics have arc-like affinities [Ohara et al.,2002]. It may indicate that the Yap-arc NYE system form as an incipient arc system atthe propagation tip of the PVR.
1.4 Previous filed surveys (southern PVB ~ Yap/Palau)
KH84-1 Hakuho-maru
Yap/Palau Trench [Kobayashi, 1985]
KH86-1 Hakuho-maru:
Yap/Palau Trench [Tomoda, 1986]
KH87-3 Hakuho-maru:
Yap/Palau Trench [Kobayashi, 1989]
S/V Takuyo 1989-1990
Northern Yap Escarpment[Iwabuchi et al., 1990]
KH92-1 Hakuho-maru
Yap/Palau Trench [Fujiwara et al., 1996a]
Y93-03 Yokosuka/ Shinkai6K#193,195 Yap/Palau Trench [Fujioka et al., 1994]
Y95-06 Yokosuka/ Shinkai6K#287~290 Yap/Palau Trench [Fujioka et al., 1996]
Y96-12 Yokosuka/ Shinkai6K#347~350 Yap/Palau Trench [Fujiwara et al., 1996b;
Fujiwara et al., 1997; Fujiwara et al., 2000; Nishizawa et al., 1994] * compilation of
Yokosuka mapping

KH03-3 Hakuho-maru
YK03-09 Yokosuka/ Shinkai6K#798~800

southern PVR
southern PVR

2. Objectives of the cruise
Written by Kyoko Okino and Yasuhiko Ohara
The primary objective of KH05-1 Leg3 is to reveal the structure of the southern tip of
the PVB, and then to confirm the evolution model proposed by [Fujiwara et al., 2000;
Ohara et al., 2002]. To tackle this problem, we will conduct the geophysical mapping of
the backarc side of the Yap trench-arc, obtain the reflection and gravity profiles acrosswhole trench-arc-basin system, and some dredge hauls. The question to be solved are:
 Evolution process of the southern tip of the PVB
 Are there N-S and/or NW-SE abyssal hills?
 Was the area formed as a western wing of the basin?
 If so, how was the fate of the eastern wing of the basin? Eroded?
 How did the junction between the PVR and the Yap Trench develop?
 The relationship of the basin evolution and the collision of the Caroline Ridge
 When and how did the Caroline Ridge collide with the Yap Trench?
 Did the Yap Island obduct the trench?
 Is the Caroline Ridge subducting now?
 The lithospheric composition of the southern tip of the basin

9

10

11

3. Summary of Operations
Written by Kyoko Okino
We conducted an extensive geophysical mapping with a seismic reflection survey andtwo dredging in the southern tip of the Parece Vela Basin during the Hakuho-Maru
KH05-1-3 cruise. The ship left Apra, Guam on 17 June, 2005 for the survey area. We
first conducted a ~150 mile geophysical profiling across the Yap Trench and then started
a box surveying in the southern tip of the Parece Vela Basin. The multibeam bathymetry,
total and vector magnetics and gravity data were collected along survey lines. A multichannel seismic reflection survey was done across the Yap Trench from 19 June to 20
June. We also performed two dredges hauls on 24 June. The survey finished on 25 June
after another across-trench profile and the ship arrived at Apra, Guam on 27 June, 2005.
The sea condition was extremely good during the cruise.
Local
UT
Notes
Date/Time Date(Julian)/Time
June 15 14:15 June 15 (166) 04:15
Departure from Guam
15:00
05:00
Science meeting
18:30
08:30
Meeting with ship officers
June 16 06:50 June 15 (166) 20:55
SeaBeam Power On
08:10
22:10
XBT-1 (failed)
08:20
22:20
Deploy proton magnetometer
08:49
22:49
XBT-2 at 9-55.5'N, 141-28.9'E
10:14 June 16 (167) 00:14
Start watch and log, checking instruments
12:00
02:00
Science meeting
13:00
03:00
Boat drill
18:57
08:57
Start geophysical mapping WP2(Profile1-E)* The MCS team assembled airguns (in day time sift).
June 17 04:04
18:04
WP3(Profile1-W)
04:16
18:16
Figure eight turn No.1 start
04:37
18:37
Figure eight end
09:50
23:50
XCTD-1 at 10-19'N134-50'E
10:35 June 17 (168) 00:35
SeaBeam down (slow down)
10:49
00:49
SeaBeam recover
11:09
01:09
WP4 (4W)
12:00
02:00
Science meeting* The MCS team checked the streamer cable (in day time sift).
June 18 01:22
15:22
WP5(4E)
02:21
16:21
WP6(5E)
08:25
22:25
POS-MV=SeaBeamGPS trouble(slow down)
08:49
22:49
Start turn to (10-05'N,137-30'E)
09:23
23:23
Resume SeaBeam survey
12:00 June 18 (169) 02:00
Science meeting1215:3005:30
WP7(5W)
16:06
06:06
Ship's rudder malfunctioned
16:16
06:16
WP8(6W)
16:30
06:30
Course change / fish boat
16:47
06:47
Back to survey line
* The MCS team checked the depth controller etc. (in day time sift).
June 19 05:57
18:57
WP9(6E)
08:45
22:45
Retreive proton magnetometer
12:00 June 19 (170) 02:00
Science meeting
13:17
03:17
MCS survey startJune 20 12:00 June 20 (171) 02:00
Science Meeting
13:53
03:53
MCS survey end; stop SeaBeam recording
16:00
06:00
XCTD-2 at 10-28'N137-12'E
16:25
06:25
Deploy proton magnetometer
17:15
07:15
Resume SeaBeam survey
18:20
08:20
WP13(4.5E)
June 21 00:31
14:31
WP14(4.5W)
01:30
15:30
WP15(5.5W)
06:15
20:15
S-curve maneuver for POS-MV stablization
06:30
20:30
On course
09:00
23:00
WP16(5.5E)
09:57
23:57
WP17(6.5E)
12:00 June21 (172) 02:00
Science meeting
16:40
06:40
WP18(6.5W)
17:12
07:12
WP19(7W)* Rock sampling team assembled the dredgers.
June 22 04:22
18:22
WP20(7E)
05:24
19:24
WP21(8E)
12:00 June22 (173) 02:00
Science meeting
15:40
05:40
WP22(8W)
15:52
05:52
XBT-3 at 9-24.5'N, 134-49.0'E
16:04
06:04
Figure eight turn No.2 start
16:24
06:24
Figure eight end
16:42
06:42
WP23(7.5W)
June 23
0:14
14:14
WP24(7.5E)
S-curve maneuver for POS-MV stablization
1:27
15:27
WP25(8.5E)
7:40
21:40
WP26(8.5W)
8:06
22:06
WP27(9W)
12:00 June23 (174) 02:00
Science meeting
12:15
02:15
Grvitimeter room tour
20:33
10:33
WP28(9E)

13June 24

21:33
3:34
5:03
6:16
6:45
7:00
7:05
11:00 June 24 (175)

11:33
17:34
19:03
20:16
20:45
21:00
21:05
01:00

16:25
20:30

06:25
10:30

22:06

12:06


June 25

3:34
3:49
4:31

17:15
17:49
18:31

5:52
19:52
6:45
20:45
10:41 June25(176)
0:41
12:00
2:00
13:30
3:30
14:20
4:20
22:12
12:12
22:15
12:15
23:30
13:30
June 26 12:30 June 26 (177) 2:30
16:00
6:00
20:00
10:00
June 27 10:00
0:00

14

WP29(10E)
WP30(10X)
WP31(8.25E)
WP32(8.25W)
Retrieve magnetometer
ArriveD-1 [9-17.67'N, 135-55.83'E, 4500m]
SeaBeam shut down
SeaBeam restart
WP35(9.5X)
WP36(9.5Y)
ArriveD-2 [9-17.67'N, 135-55.83'E, 4500m]
XBT-4 at 9-6'N, 134-23'E
Deploy proton magnetometer, resume
mapping
WP39(9.5X)
WP40(9.5W)
WP41(10W)
WP42(10Y)
WP43(11Y)
WP44(11Z)
WP45(10Z)
WP46(10X)
Science meeting
Engine room tour
Profile2-W
Profile2-W (Survey End)figure eight
Retrieve magnetometer
Group photo
Science meeting
Farewell party
Arrive at Guam

4. Explanatory notes and Preliminary results
Written by Kyoko Okino
4.1 Bathymetry survey
4.1.1 Operations
During the KH05-1-3 cruise, we continued to record bathymetry data in the survey area,
except for the area during some station operations. We conducted in total ~ 2800 milesof swath survey during the cruise, mainly along the east-west trending survey lines. The
swath coverage is ~90% in the western half of the survey box and ~40% in the eastern
half. The survey lines are shown in Fig.4 and the detailed coordinates of the lines arelisted in Table 1. We started logging on 2005/06/16 08:57UT on the northern Caroline
Ridge and stopped logging from 2005/06/20 03:53UT to 2005/06/20 07:15UT for airgun recovery and from 2005/06/23 21:05GMT to 2005/06/24 01:00UT for dredge
operation D-1. We finally finished mapping on 2005/06/25 12:12UT in the southern
Caroline Ridge area. The data logging was stopped for rebooting from 2005/06/22
09:01 to 09:07UT, 2005/06/22 15:27 to 15:30UT, and 2005/06/22 16:13 to 16:15UT
because of trouble in the POS-MV positioning system described later.
Bathymetric data were collected by SeaBeam2120 on R/V Hakuho-maru. SeaBeam2120
is a multibeam survey system that generates data for and produces wide-swathbathymetry maps and backscattering images. The system consists of two main
subsystems, transmitter and receiver respectively. The basic 20 kHz projector array is a
14-foot long linear array positioned fore and aft along the ship’s keel. The receiver array
detects and processes the returning echoes through stabilized multiple athwartshipbeams in a fan shape. The system synthesizes 1° by 1° narrow beams at an interval of 1°.
The swath width decreases from 150° to 60° with increasing water depth. The transmit
interval of the sonar also varies from 10sec to 13sec in the survey area. The accuracy ofthe depth measurement is reported as 0.5% of the water depth. The pinging and signal
processing were controlled by “Hydrostar” software on Windows PC in No.1
Laboratory, in which the operator can set the ship parameters (draft = 6.0m, roll bias =0.2°, pitch bias = 0.0°), sound velocity profiles, ping power and gain, swath width etc.
For the automatic swath width control system forced the swath width narrow to 90° in
the area deeper than 4000m, we tried to widen it to 110° or 120° manually during thedata acquisition. All data were transmitted to the SGI O2 workstation “surveyor”, where
the data were logged in mb44 (=mb94) format at an interval of 125 or 250 pings per filefor ease in editing and transporting the data.
The ship position and attitude data were collected by POS-MV GPS system customized
for multibeam echo sounders. The heading data are usually obtained by integrating the
IMU (Inertial Motion Unit) gyro heading and the GAMS (GPS Azimuth Measurement
Subsystem = azimuth measurement using two GPS antennas). The integrated heading
measurement system provides a heading value with high accuracy (~0.07°), however
the decreasing accuracy (> 0.1°) and The jumps and/or errors in heading measurements
were frequently encountered during the later half of the cruise. We fixed the problem bysimply rebooting the system in case of large heading jump or errors at 2005/06/22 09:01

15

to 09:07UT, 2005/06/22 15:27 to 15:30UT, and 2005/06/22 16:13 to 16:15UT. We
continued the survey with lower accuracy (~0.8°) without GAMS from 2005/06/22
16:15UT to 2005/06/23 21:05UT. During this period, the GAMS was always “Off-Line”
or “Not Ready” modes. The same problem was also reported in the previous cruises.
The SeaBeam system uses sound velocity data for both calculating the depth andposition of each beam during the ray tracing process, and for the beam forming process.
The sound velocity of the surface layer is most important in this regard, so the system
includes a surface sound velocity meter for real-time monitoring of the surface velocity.
Except for the surface layer, data from XBT and XCTD measurements (max depth =1830 m) were used for calculating sound velocities. For depths greater than 2000 m, theLevitus database was used. We conducted four XBT measurements (three succeeded,
one failed) and two XCTD measurements. The locations of these measurements areshown in Fig.4 and the details are listed in Tables 2. The sound velocity profiles usedduring the survey are listed in Appendix-A.

Figure 4 Survey lines of geophysical mapping. Locations of dredge hauls, XBT/XCTD
and figure eight turns are also plotted. Numbers indicate main way points (see Table 1).

16

Table 1 List of waypoints
way point
Profile1-E
Profile1-W
4W
4E
5E
5W
6W
6E
MCS-S
MCS-E
4.5E
4.5W
5.5W
5.5E
6.5E
6.5W
7W
7E
8E
8W
7.5W
7.5E
8.5E
8.5W
9W
9E
10E
10X
8.25E
8.25W
D-1
9X
9.5Y
D-2
9.5X
9.5W
10W
10Y
11Y
11Z
10Z
10X
Profile2-W
Profile2-E

17

Lat [deg]
9
10
10
10
10
10
9
9
9
10
10
10
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8
8
9
9
9
9
9
9
9
9
8
8
8
8
8
8
9
8

[min] Lon [deg]
56
41
19
19
5
5
51
51
57.5
27
12
12
58
58
44
44
37
37
23
23
30
30
16
16
9
9
55
55
19.5
19.5
18
2
2
7
2
2
55
55
40
40
55
55
2
14

139
136
134
138
138
134
134
138
139
137
136
134
134
136
136
134
134
137
137
134
134
136
136
134
134
138
137
136
136
135
135
135
136
136
135
134
134
135
135
135
135
136
137
139

[min]
0
30
50
20
20
50
50
15
0
20
45
55
55
50
50
55
55
51
47
50
50
35
35
50
50
0
55
10
10
50
56
56
28
23
58
50
50
2
2
9
9
10
4
0

Date
06/16/2005
06/16/2005
06/17/2005
06/17/2005
06/17/2005
06/18/2005
06/18/2005
06/18/2005
06/19/2005
06/20/2005
06/20/2005
06/20/2005
06/20/2005
06/20/2005
06/20/2005
06/21/2005
06/21/2005
06/21/2005
06/21/2005
06/22/2005
06/22/2005
06/22/2005
06/22/2005
06/22/2005
06/22/2005
06/23/2005
06/23/2005
06/23/2005
06/23/2005
06/23/2005
06/23/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/24/2005
06/25/2005
06/25/2005
06/25/2005

Time [UT]

JD

8:57
167
14:09 1:09
168
15:22 16:21 5:29
169
6:34 
18:57 
2:41
170
3:41
171
8:20 
14:38 15:36 23:00 23:57 6:36
172
7:09 
18:22 19:24 5:40
173
6:42 
14:16 15:27 21:35 22:05 10:34
174
11:33 17:37 19:07 20:15 21:12 3:23
175
5:29 
6:41 
13:12 17:16 17:49 18:31 19:27 19:54 20:47 0:40
176
4:12 
12:10 

Table 2

Locations of XBT/XCTD observations

Sites
XBT-2
XBT-3
XBT-4
XCTD-1XCTD-2Time
Date
2005/06/15 22:49
2005/06/22 05:51
2005/06/24 19:17
2005/06/16 23:50
2005/06/20 06:05* XBT-1 failed.

Lat[d]
9
9
9
10
10

[min]
55
24
6
19
28

Lon[d]
141
134
134
134
137

[min]
29
49
23
50
12

Depth[m]
1833
1833
1833
1101
1951

4.1.2 Data editing and processing
After SeaBeam data was logged as “.mb44” files on the SeaBeam workstation, files
were ftp-ed to the “mapper” workstation and several other computers on the LAN with
MB-System [Caress and Chayes, 1996], which was used for data editing, gridding, andmap production. The file extension of raw data file is mb44, however the format 44 is
identical to format 94 in MB-System and the “.mb94” is appended to the processed file.
A flow chart of the processing procedure and outputs is as follows. The MB-System
5.0.7 and GMT4.0 [Wessel and Smith, 1998] were used.
1. mbedit – checking data quality ping by ping, editing bad beams. The processcreates “.esf” and “.par” files.
2. mbnavedit– checking navigation data quality and editing. COG (course maygood) data are adopted instead of heading for some periods (see Appendix B).
The process creates “.nve” files.
3. mbprocess – applying the edits to the original “.mb44” files. The processcreates “p.mb94”, “.fbt”, “.fnv”, and “.inf” files.
4. mblist – listing the longitudes, latitudes, and depths for all beams for all pings.
Usually we can use mblist –D option (dump mode), but the option does not work
for mb94 format and “mblist –M0/120 –OXYZ” are used. The process creates“.xyz” files.
5. The masked grid is created using the following script.
#! /bin/csh#
make grid file from xyz files#
set region = 134:45/139/8:30/10:50# grid region
set int = 0.05m# grid interval
set tension = 0.65 # surface tension factor
set radius = 2k
# search radius
set blkfile = kh0501-3.blk # block file
set grdfile = kh0501-3.grd # grid file
set maskedfile = kh0501-3.masked.grd#
cat ../xyz/0616/*.xyz ../xyz/0617/*.xyz ../xyz/0618/*.xyz ../xyz/0619/*.xyz ../xyz/0620/*.xyz ../xyz/0
621/*.xyz ../xyz/0622/*.xyz ../xyz/0623/*.xyz ../xyz/0624/*.xyz ../xyz/0625/*.xyz |¥awk '{if($3 > -8500 && $3 < 0) print $1,$2,$3}' |¥blockmedian -R$region -I$int -V > $blkfile18

surface $blkfile -R$region -I$int -T$tension -G$grdfile -V
grdmask $blkfile -R$region -I$int -NNaN/1/1 -S$radius -Gmask.grd -V
grdmath $grdfile mask.grd OR = $maskedfile

4.2.3 Morphology of the southern tip of the Parece Vela Basin
The overall bathymetric map is shown in Fig. 5. The survey area covers from the Yap
Trench in the east to the foot of the Kyushu-Palau Ridge in the east. West of the
topographic highs including the Yap Island, the southern tip of the basin divided into
four areas (Fig. 6).
Area A: Along the Yap Trench, the area shallower than 3800 m extends toapproximately 50 miles west of the trench axis. The area is characterized by short NWSE abyssal hills. The abyssal hills are clear in the northern part of the area, and seem tobe offset by NE-SW trending discordant zones. The area may be the southern extensionof the central area of the Parece Vela Basin.
Area B. West of the Area A, the seafloor is characterized by well-ordered north-south
trending abyssal hills. The abyssal hills are relatively continuous and the water depth
ranges from 3800 to 4800 m. No clear fracture zones are recognized. The area is Vshaped and its western boundary of is linear and prominent (thick line in Fig. 6). These
facts presumably indicate that the area is the propagating tip of the Parece Vela Basinspreading ridge in the east-west spreading stage. The northern extension of thisboundary is ambiguous and the north-south abyssal hills are also observed on thewestern part of the northern two survey lines.
Area C: West of the V-shaped propagator, the trend of abyssal hills abruptly changes to070°~080°. The area intervenes between the propagator tip and the western curved
deeps and may be a kind of transferred lithosphere between two spreading centers. A
few conical seamounts are distributed in the southern part of the area.
Area D: The most prominent morphology in the survey area is en echelon, curved deeps
east of the Kyushu-Palau Ridge. Two deeps (at10°15’N and at 9°15’N) are crescentshaped and curve towards northward. The northern deep is ~6100 m and the southern
one is ~4500 m. The abyssal hills outside the northern deep seem approximately
perpendicular to the curved deep structure. The southwestern extension of the northern
deep is a narrow curved rift trending 030° and the rift develops within a topographic
high. On the other hand, the area north of the southern deep is characterized withvoluminous dome, which consists of branched topographic highs. Out of our survey
area, the similar curved deep can be recognized on the satellite altimetry map around
8°40’N.
The morphological pattern with curved deeps is very much like those of the Pito Deepof the Easter Microplate [e.g. Naar and Hey, 1991] and of the Endeavor Deep of theJuan Fernandez Microplate [e.g., Kleinrock and Bird, 1994]. It may suggest that arotational deformation associated with continuous rift propagation and some finite
broad transform zone is related to the origin of the enigmatic structure of the area.

19

20

21

4.2 Gravity survey
Written by Sang-Mook Lee
The measurement of gravity field, checking its quality and subsequent reduction
constituted an important part of our field activity during Leg 3 of cruise KH05-1. The
survey area, Yap trench system, comprises of subducting Caroline Ridge, the trenchitself, Yap arc and the backarc section. The Caroline Ridge, a massive volcanic feature
formed on the border of subducting Pacific-Caroline plate, is divided into two along the
WNW-ESE trending Sorol Trough. The characteristics of the Yap trench systemappear to differ between the north and south of the Sorol Trough, according to the recent
study using regional satellite-derived gravity measurement [Lee, 2004]. One of theimportant aims of our gravity study is to investigate the nature of such structuraldifference using onboard marine gravity measurement, which is considered to be more
precise than that of the satellite. This report describes the gravity field measurement
taken during cruise KH05-1 Leg 3.
The measurement was made continuously through the entire length of the cruise, whichbegan on June 15, 2005 in Apra, Guam and ended on June 27, 2005 in Apra, Guam. In
this section, we provide a brief description on the gravimeter system onboard R/V
Hakuho-Maru, calibration of the instrument, estimated drift, and measurement itself andreduction to free-air gravity anomaly. A comparison is made between the free-air
gravity anomalies obtained in this cruise and those derived from satellite altimeter data.
Finally, some remarks are given on the direction of post-cruise gravity analyses.
4.2.1 Gravity Meter System
The gravity meter on board R/V Hakuho-Maru is Dynamic Gravity Meter D-004 and
ZLS GyroPack (GG-49) made by ZLS Corporation, USA (www.zlscorp.com). It is a
Lacoste and Romberg type gravity meter (Figure 7), and the operating system is
UltraSys™. The control system basically consists of remote and host computers. The
former performs all real-time activity associated with controlling the platform andgravity meter as well as maintaining the system clock. The latter receives the data,
computes the cross-coupling correction, and performs the final filtering before archiving
the data. Time is kept very accurately by a temperature-compensated crystal oscillator.
During this cruise, the gravity meter was set at normal sea mode, which outputs thefiltered data at 10-second intervals. These data are reduced to 1-minute-interval
outputs by the host computer.
The gravity meter requires a careful calibration in order to estimate the absolute gravity
value. This tie is done using a reference station on land. The calibration tie was doneat Ocean Research Institute of University of Tokyo and again at Apra Harbour (WharfH) in Guam before the start of the cruise by technical staff (K. Koizumi). The tie wasmade using portable Lacoste and Romberg Land Gravity Meter G-124 (Table 3).

22

While the drift rate of the instrument was not measured at this particular leg,traditionally this value is reported to be less than 2-3 mgal per month.

Figure 7 Photo of ZLS Dynamic Gravity Meter D-004 installed in 2nd deck laboratory
of R/V Hakuho-Maru.

Table 3 Result of calibration of D-004 gravity meter on board the ship with a Lacoste
and Romberg Model G Land Gravimeter (G-124) in Guam.
G-124
Location
Day
G-124
D-004
(Tie)
Guam (Apra, Wharf H) 2005/06/14 2175.8
978510.3 978510.3
Guam

4.2.2 Measurement
To dampen the ship’s motion, gravity measurement is subject to a special low-pass filter.
Due to this filtering, the gravity output from the host computer has a 4-minute delay.
At first the gravity is calculated without considering the time delay. This is called thepseudo gravity. The true free-air gravity anomaly, however, comes from the gravity
reading corrected for the Eötvös effect and latitudinal variation using navigational datataken 5 minutes ago. Below is an example of output file data format.

23

date
lat
lon
sco
ssp
gyro log
cur.dir PDR SB
Gmat5:50+Et1 Gn
Et1(used) Et2
FA2
Gmat5:56 FAat4:55
Gn
C
FAA
06/16 04:55 9.6001 140.11 286.9 +16.68 287.3 15.80 332.3 2683.6 02713 978187.86
978175.46 -118.065 -111.596 000020.33 978314 20.475
06/16 04:56 9.60146 140.106 286.8 +16.70 288.2 16.10 310.2 2666.4 02703 978189.92
978175.50 -118.268 -113.144 000021.22 978316 22.232
06/16 04:57 9.60146 140.106 286.8 +16.70 288.2 16.10 310.2 2666.4 02703 978189.92
978175.50 -118.268 -113.144 000021.22 978316 22.232
06/16 04:58 9.60281 140.101 286.7 +16.73 287.7 16.30 331.2 2658.0 02684 978191.85
978175.54 -118.543 -114.873 000021.93 978317 22.917
06/16 04:59 9.6042 140.097 286.8 +16.77 287.8 16.20 314.9 2659.6 02696 978193.50
978175.58 -118.763 -114.104 000022.47 978317 22.657
06/16 05:00 9.60558 140.092 286.7 +16.81 288.2 16.70 323.0 2595.2 02674 978194.86
978175.62 -119.108 -117.359 000022.85 978318 23.272
AB
A = filtered pseudo gravity at 05:00 valued already added by B
B = Eötvös correction at 05:00
C = Eötvös correction at 04:55
Gn = latitudinal correction at 04:55
Thus the true free-air anomaly (FAA) can be calculated as:
FAA = A – B + C – Gn
which in this case is 20.475 mgal at 04:55.
Figure 8 is a map of free-air gravity anomaly plotted along the survey trackline. Itshows a negative free-air anomaly of -320 and -180 mgal across the Mariana trench andYap trench, respectively. The Yap arc and Caroline Ridge have a large positive
anomaly of approximately 50-60 mgal. The back-arc side of the Yap trench in generalshows up as having a slightly positive anomaly. However, the deep escarpments havenegative anomalies.
The free-air gravity field anomaly measured during our cruise was compared with thatderived from the satellite altimetry data [Smith and Sandwell, 1997] (Figure 9). The
version satellite free-air gravity anomaly that we used is a 2-minute version. The two
measurements appear to match quite well, except for slight differences at the peaks andtroughs. This finding suggests that we can use satellite-derived gravity anomalies
around the study area for regional studies.

24

Figure 8. Free-air gravity anomaly plotted along the ship trackline.
topography of the survey area is also drawn with contours at 1-km intervals.

25

SeafloorFigure 9. Comparison of ship-board free-air gravity anomalies and those derived fromsatellite altimetry data. The overall variations match quite well.

26

4.3 Magnetic survey
Written by Toshiya Fujiwara
4.3.1 Total Force Measurement
During the KH05-01 Leg 3 cruise, underway geophysical surveys, whose items
included were gravity and geomagnetics, were conducted aboard the R/V Hakuho-maru.
The aim of the geophysical surveys was to provide a detailed geophysicalcharacterization of the lithosphere in the southern tip of the Parece Vela Basin and the
Yap Trench, which will be used to unravel tectonic evolution and crustal structure.
Geomagnetic total force data were obtained by using a surface-towed proton precession
magnetometer PR-745 (Kawasaki Geol. Eng. Co.) (Fig. 10). The sensor was towed 350
m behind the ship (Fig. 11). The data were collected every 30 seconds. The following
data processing was made onboar: After removing spike errors and positioning
correction taking into account the sensor cable length, the geomagnetic total force
anomaly was calculated by subtracting the International Geomagnetic Reference Field(IGRF) 9th generation [IAGA, 2003] as the reference field.

Figure 10
PR-745 proton precession magnetometer settled in NO.3 Laboratory.
The controll unit of the magnetometer is in the left-hand of the photograph, and thecomputer in the right-hand records magnetic data merged with ship's navigation data.

27

Figure 11
behind the ship.

The winch of sensor cable is on deck. The sensor is towed 350 m

Figure 12 shows wiggle plots of magnetic total force anomaly along the ship track. The
magnetic anomaly pattern is complicated as with bathymetric morphology in this area.
Some peaks of magnetic anomalies are correlative between parallel tracks, but nomagnetic lineation is clearly identified.
Amplitude of the magnetic anomaly in the west side of the Parece Vela Basin (>250 nT
peak-to-trough) is generally higher than in the east side (<200 nT). In consideration ofbathymetric morphology, the magnetic anomaly amplitudal difference may be caused
from that the water depth in the west side of the basin is shallower, therefore shorter
distance to the oceanic crust as a magnetic source, the topography is rough, and theseafloor fabric shows omnidirectional. Whereas in the east side, the water depth isdeeper, and the strike of the basin fabric, which is the possible magnetic lineation, has anearly north-south direction which makes the geomagnetic signal a minimum.
Because the study area is situated in low magnetic latitude, diurnal variation may effectthe observed magnetic anomaly, significantly, thus correction of the diurnal variation
may be needed. Long-wavelength variations, uncorrelated between the ship tracks,
appear on the observed magnetic anomaly profiles (Fig. 12). Further data analysis
should be processed to remove skewness due to low magnetic latitude and to correct foreffects of seafloor topography, and to evaluate the crustal magnetization distribution.

28

Figure 12
Wiggle plots of magnetic total force anomaly along the ship tracks
superimposed on the ETOPO2 bathymetry. Red shade indicates positive anomaly.
Yellow circles point locations of "Figure-8" turns (See the next section).
4.3.2 Vector Field Measurement
Vector magnetic field data were collected using a shipboard three-component
magnetometer, SBM-89 (GAUSS) (Figs. 13 and 14). Ship's roll and pitch values were
provided from the POS-MV system, and ship's heading value were obtained from
TG5000. The data were collected with a sampling rate of 1 second throughout the cruise.
"Figure-8 turn"s (a ship runs along an 8-shaped track consisting of two circles) weremade for calibration of the ship's magnetic effect, related to magnetic susceptibility ofthe ship, and a permanent magnetic moment of the ship's body [Isezaki, 1986]. The
turns were made at three locations (Table 4). The IGRF 9th model was also employed as
the reference magnetic field for calculation of vector geomagnetic anomaly and "Figure8" calibrations. The resultant calibration coefficients are shown in Table 5.
Magnetic vector anomalies will be utilized to map the strike directions of lineatedmagnetic boundaries, which are commonly representing lithological boundaries,
geomagnetic reversals, or topographic offsets of magnetized layers due to faults. This
study area is located near the magnetic equator. It makes the geomagnetic signal small.
Magnetic vector anomaly is an effective approach to the study of magnetic anomaly inthis area, because the vector anomaly field is free from effects of direction of ambient
geomagnetic field.

29

Figure 13
SBM-89 settled in NO.1 Laboratory. The controll unit of themagnetometer is on lower of the rack, and the computer records magnetic data mergedwith ship's navigation and motion data.

30

Figure 14
the bridge.

The fluxgate sensor of SBM-89 is settled on the upper deck above

Table 4 Summary of "Figure-8".
1. 6/16 18:16-18:37 (UT)
10°42'N, 136°27'E IGRF X: 37484 Y: 388 Z: 4118 nT
2. 6/22 06:04-06:27 (UT)
09°27'N, 134°48'E IGRF X: 37877 Y: 422 Z: 2396 nT
3. 6/25 12:15-12:27 (UT)
08°14'N, 139°00'E IGRF X: 37330 Y: 1064 Z: 657 nT
Table 5 Coefficients of calibration A-matrix. Coefficients a11~a33 are related tomagnetic susceptibility of the ship, and a14, a24, and a34 indicate a permanent magnetic
moment of the ship's body.
a11=0.95666
a12=-0.07742
a13=-0.00220
a14=28.5
a21=0.08021
a22=0.86709
a23=-0.00365
a24=-1811.4
a32=-0.00691
a33=1.06336
a34=6517.0
a31=-0.08564

31

4.4 Multichannel seismic reflection survey
Written by Yasuyuki Nakamura,
Hiroyuki Inoue, Hideo Ishigaki andShinichro Yokogawa
Multichannel seismic (MCS) reflection survey was conducted on one across trench line
during KH05-1 Leg3. We started the MCS survey at 0317 on 20th (UTC) and finished
at 0353 on 21st (UTC). The length of the survey line was ~100 nautical miles.
4.4.1 Seismic sources
Three Bolt 1500C air guns were towed from stern of the Hakuho-maru with separated
towing harness in parallel. The distance from the stern to air guns was ~15 m (Figure15). The total volume of the chamber of air guns was 57 littres (~3400 inch3). The
starboard and center air guns had 20 littres chamber, and port air gun was 17 littres. Two
Hakuho-maru’s compressors sent the air with high pressure to air guns. Air guns were
fired at 110 bars (~1600 psi) of air pressure. We fired 4355 shots during the MCS
survey.
4.4.2 Firing system
Figure 16 shows the block diagram installed in No. 3 Lab. A shot pulse generator,
provided by Earthquake Research Institute (ERI), University of Tokyo, generates theshot pulse every 20 seconds. A shot time randomizer, provided by Dr. E. Araki in
JAMSTEC, was used to randomize the shot time. The randomizer adds random time
between 0-0.6 s to the shot pulse timing so that the multiple reflection from the seafloor
can be weaker after stacking. A closure pulse generator, provided Dr. K. Mochizuki in
ERI, receives the randomized shot pulse and sends the closure pulse to the firingcontroller, AutoSync (Input Output Inc.). AutoSync was configured to synchronize theshot timimg 450 ms after receiving the closure pulse. Two AutoSyncs were used tosynchronize the shot timing of three air guns. Thus, air guns were fired every ~20 s with
+0-0.6 s fluctuation. Hakuho-maru kept her speed against ground at ~ 4kt during MCS
survey, which yields that the shot interval was ~40 m in distance.
4.4.3 Seismic receivers
The ORI’s 48 channel solid streamer cable made by ITI was used as a receiver array of
MCS survey. The streamer cable consists of tail section, active section, and lead-in
section. A ~200 m tail rope was attached at the end of the tail section to stabilize thestreamer cable. The length of the active section of the streamer cable was 1200 m. The
lead-in cable payout was ~114 m from the stern. The streamer cable was powered by acouple of 12 Volts car batteries. The seismic data from the streamer cable was recodedby the acquisition computer (StrataVisorNX48) into DDS-4 tapes and HDD in SEG-D
8058 format. The record length and the sampling interval were 15 s and 2 ms,
respectively. Note that the data of #25-#36 channel were recorded as #36-#25 channel
due to the wrong cable connection built in the adapter cable between the acquisition

32

computer and the deck cable; e.g. #25 channel in the streamer is recorded as #36
channel in the recorded data, #26 in the streamer is #35 in the data etc. The
StrataVisorNX48 receives a trigger signal from the randomizer to start the recording ofeach shot data, so the timing of the recording and shot was synchronized at each shot.
The nearest channel (channel #1) was dead entirely during survey. The depth of thestreamer cable was controlled by Syntron’s MULTITRAK system using 5 birds. Birds
were attached to the streamer cable at the point of 0 (bird #1), 300 (bird #2), 600 (bird#3), 900 (bird #4), 1200 (bird #5) m from the head of the active section (Table 6). Threeof them (#1, #3, #5) were also equipped with a compass so that the orientation of thebird is logged and the shape of the streamer cable can be calculated. The bird depth was
set at 10 m. During this cruise, bird #3 was not responding when it is in the water.
However, the depth of other birds was well controlled at around 10 m, and the streamer
shape was kept almost straight.
4.4.4 Log
Watch standers took the log every 15 minutes onto the logbook for following items;
Time (UTC), ship position, ship course and speed made good, heading, ship speed
against water, water depth, recording file number, bird depth, fire time, air pressure andnotes. The log was also taken at any events, e.g. problems, passing waypoints etc.
4.4.5 Problems
Basically the MCS survey was successfully operated during the survey. All of three air
guns were fired at all shots, however, minor problems occurred as following.
1. Battery of the closure pulse generator
The closure pulse generator operates with 9V battery. The life of the battery was ~2.5
hours, which was much shorter than expected before the cruise. We needed to change
the battery manually when it was dead. It took a few minutes to change the battery. The
shooting of air guns was stopped while we were changing the battery. The longest stopwas ~ 8 minutes at the trench area because power line broke at that time.
2. Battery cable for streamer cable
In the beginning of the survey, the power cable of the streamer cable was snapped by
accident twice. While powered off, the air guns were fired and the acquisition computer
continued the data recording but no waveform was sent from streamer cable. This
problem happened during the first 75 shots.
3. Miss-triggered acquisition
The triggering of the seismic data recording was sometimes not synchronized with thefiring time. The reason was not resolved yet. Eighty-five shots were miss-triggered.
Some of them may be able to use for processing after adjusting the trigger time usingwith the direct wave arrival.
4. Duplicated shot number
The total volume of the seismic data was ~6 GB. Because 6 GB was too large to savethem in one partition of the acquisition computer, we needed to switch the partition of
the data storage space while the survey was under way. When the switching occurred,
the acquisition computer miss-numbered the file number of the data, which were33

duplicated. The shot number 3291 and 3292 were duplicated files.
4.4.6 Onboard processing and quality check
A Sun Blade 100 workstation was brought from ORI into No.3 Lab., and used foronboard processing and quality check of the seismic data. “Seismic Unix” free software
packages installed on the workstation was used for this purpose. We checked the shot
gathers and found the triggering of the data acquisition was ~0.2 s earlier than thetiming of the randomized shot pulse which is 0.45 s earlier than the real shot timing. We
calculated this static time using the arrival of the direct wave, resulting that the data
should be shifted upward 0.637 s to adjust to the real shot timing; e.g. the dataacquisition was triggered 0.637 s earlier than the real shot time. Filtered neartrace
section was created as a preliminary result of the MCS survey. We applied a low cut
filter which has a corner frequency at 8 Hz.
Table 6 Bird setting. Distance is measured from the head of active section. Bird #3
equipped a compass but was not working

Bird #1
Bird #2
Bird #3
Bird #4
Bird #5
Distance 0
300
600
900
1200
S/N
1403
1309
1425
935
1386
Not
Compass 
N/AN/A
working

Figure 15 Positioning information. A is the GPS antenna. CS is the center of the source(assumed). St is the streamer cable position at stern. NT is the head of the active section.
CNT is the center of the near trace section (channel #1).

34

Figure 16

35

Block diagram of the MCS onboard system installed in No.3 Lab.

Figure 17 Shotpoint map.

36

Figure 18(a)37Filtered neatrace section for shot 1-2400.

Figure 18(b)38Filtered neatrace section for shot 2000-4355.

4.5 Dredging
Written by Yasuhiko Ohara
4.5.1 Dredge assembly
We used the ORI-TI type dredge (Fig. 19) during the KH05-01-Leg3 cruise. This
dredge has been used extensively in the JAMSTEC cruises for the past several years.
The dredge assembly used in this cruise is slightly different from that used in theprevious JAMSTEC cruises (c.f., KR03-01 cruise report; Ohara et al., 2003). The
difference includes the size and length of fuse wire. Leader wire was not employed. As
shown in Fig. 1, it consists of a normal steel (20 mm thick) box type jaw (60 _ 45 cm
mouth, 60 _ 27 cm throat, 16 cm deep) with a steel handle (26 mm diameter, 85 cmlong), and a steel chain-bag (6 mm diameter, 100 cm long) with a stainless steel (5 mmthick) box type bucket (27 _ 60 _ 50 cm). The bucket can recover all kinds of geologicalsamples including soft sediments, sands, pebbles and large rocks. It is connected withshackles (16 mm diameter with a square head) to a 25 cm fuse wire (6 mm diameter),
together with a second (100 cm long) and a third (200 cm long) fuse wire (8 mmdiameter), as described below.
Main wire
It is an installed winch wire of the R/V Hakuho for scientific observation. It is piano
wire of 14 mm diameter, ~ 15000 m long, 0.815 kg weight per one meter in the water,
having a 16.9 ton breaking strength.
Heavy chain
Heavy chain (18 mm diameter, 5 m long, 50 kg weight and about 6 ton breaking
strength) was used to stabilize the dredge assemblage and was connected to the wire
leader with a 3 ton swivel and shackles. Two weights (200 kg weight and 50 kg pipe
dredge type weight) were attached to the heavy chain to add additional stability andattempt further sample recovery.
200 kg weight
The weight was used to ascertain when the dredge is on the bottom since it can beobserved by the tension meter in the operation room. It was connected with shackles tothe heavy chain, together with a 1 ton swivel, and two fuse wires (8 mm diameter, 100
cm and 200 cm long, a 2.5 ton breaking strength).
Pipe dredge
This pipe dredge (50 kg weight, 30 cm diameter and 50 cm long) serves both as astabilizing weight and common small cylinder type dredge. It was also connected to theheavy chain in the same manner as the 200 kg weight, as shown in Fig. 1.
Fuse wire
Fuse wire (6 mm diameter, 25 cm long and a X ton breaking strength) was prepared torelease the dredge from big bites that might damage the main wire. It was connected to39the heavy chain with a 3 ton swivel and shackles in the dredge assemblage. In the caseof the ORI-TI-type dredge, two additional fuse wires (8 mm diameter, 100 cm and 200
cm long, 2.5 ton breaking strength) were connected as shown in Fig. 20. This allows the
ORI-TI-type dredge to be hauled toward a different direction by the second fuse wire if
the first fuse wire was broken due to anchoring. The third fuse wire is designed to workin the same manner as the second fuse wire, if the second fuse wire was broken. Thechange in hauling direction can hopefully release the dredge from big bites that might
damage the main wire and/or anchoring.
Life wire
One end of the life wire (10 mm diameter, 7 m long, 3.9 ton breaking strength) wasconnected parallel with fuse wires and the another end was connected with the upper
middle part of the chain-bag, enclosing the chain-bag (see Fig. 19). The life wire wasdesigned to close and recover the chain-bag dredge with rock samples secured in thelower part, in the case all fuse wires were broken by a big bite or anchoring.
4.5.2 Dredge results
We performed in total 2 dredge hauls during the KH05-1-Leg 3 cruise, focusing of thehook-shaped ridge at ~ 9°20’N (Fig. 20). The dredge sites are listed in Table 7 and thedetailed bathymetric map of each dredge site and dredge logs are shown in Appendix.
The main results are summarized as follows:(1) The dredge D1 was on the western escarpment of the hook-shaped ridge (Fig. 21)
and recovered heavily weathered pillow basalts, coarse-grained suspicious plutonic
rocks, pumices and mud balls. Maximum tension during this haul was ~ 6.6 tons. No
fuse wires were damaged.
(2) The dredge D2 was on the eastern escarpment of the hook-shaped ridge (Fig. 22).
The dredge encountered maximum tension ~ 8.8 tons several times, and the first fusewire was broken. The dredge recovered a large amount of mud balls.
4.5.3 Description of the dredged samples
Since the onboard rock saw was not available during the cruise, the samples recoveredfrom the KH05-1-Leg 3 cruise were not being able to be curated during the cruise.
Dredge 1: 9°20'N hook-shaped ridge western escarpment
In this dredge haul it was intended to try to sample the lower crust of the western
escarpment of the 9°20'N hook-shaped ridge. The bathymetry look similar to the Pito
Deep, northern end of the Easter microplate, where deep crustal rocks are exposed.
Although we hoped to recover lower crustal rocks, the dredge contained weathered
pillow basalts, coarse-grained suspicious plutonic rocks, pumices and mud balls (Fig.
23). The degree of weathering of the pillow basalts are heavy (Fig. 24A). The coarsegrained suspicious plutonic rocks include very large grain of euhedral pyroxene or
hornblende (maximum ~ 5 mm in length) (Fig. 24B, 24C). These suspicious plutonic

40

rocks also look very weathered. It should be noted that all the rocks recovered from
dredge 1 has only trace amount of Mn-coating (Fig. 23).
Dredge 2: 9°20'N hook-shaped ridge eastern escarpment
In this dredge haul we hoped to sample the Parece Vela Basin lower crust, if any exist.
However, the dredge recovered only a large amount of mud balls. These mud balls are
relatively thick Mn-coated (Fig. 23).

41

KH03-3 Fuse wires:
6mm 25cm
8mm 100cm
8mm 200cm

Figure 19. ORI-TI type dredge assembly42

Table 7

List of the dredge site during KH05-1-Leg 3 cruise
Start (on bottom)

End (off bottom)

Dredge

Local

Haul

time

Lat.

Lon.

Depth (m)1

June 249°17.71'N

135°55.85'N

4292

9°18.77'N 135°56.44'N

3634

2

June 249°06.88'N

136°23.17'N

4893

9°06.15'N 136°23.15'N

4511

43

Lat.

Lon.

Depth (m)Setting

Main lithologies recovered

9°20'N hook-shaped ridge

weathered pillow basalt; coarse-grained

western escarpment

suspicious plutonic rock; pumice; mud ball

9°20'N hook-shaped ridge
eastern escarpmenta large number of mud ball

Figure 20

44

Bathymetry of the dredge sites. Red circles indicate two dredging locations.

Figure 21 . Detailed bathymetry of the dredge D1. Arrow indicates direction of thedredge haul.

45

Fugure 22 Detailed bathymetry of the dredge D2. Arrow indicates direction of thedredge haul.

46

Figure 23

47

Overall photos of the dredges D1 and D2 samples.

Figure 24 Close-up photos of the samples from dredge D1. (A) Heavily weathered
pillow basalt. (B) Coarse-grained suspicious plutonic rock. (C) Very large grain ofeuhedral pyroxene or hornblende (maximum ~ 5 mm in length) in coarse-grained
suspicious plutonic rock.

48

5. Future works
Rapid publications
1. Okino , Ohara et al. to be submitted to InterRidge News or GRL.
2. Okino, Ohara et al. to be submitted to AGU Fall meeting in 2005.
Morphology and Tectonics
Okino plan to process the side-scan data collected by seabeam2120 and to study thetectonics of the survey area. The comparative study with rotational tectonics in othermid-ocean ridges will be done. Okino and Ohara will continue to establish the complete
scenario of the Parece Vela Basin evolution.
Gravity
Lee and Kim shall analyze the marine gravity data to improve our knowledge of thetectonic and magmatic structure and processes of the Yap trench-arc-backarc system andinteraction between the Pacific-Caroline and Philippine Sea plates. This study will
involve the use of complementary data set such as the multi-channel seismic profile
from which one derive information on the crustal density structure from seismic
velocities. Lee and Kim also plan to continue the analysis of gravity anomaly on aregional scale. In particular, it will be important to understand how the topography of
the Yap trench system is maintained. We intend to compare between various isostatic
models and flexural models. Another important item for our research is to understandthe difference in the subduction style of Caroline and Pacific plates with respect to theSorol Trough. Our previous study has shown that there is a difference, but this argument
needs to be validated by data set with a greater coverage. The acquisition of marine
gravity data set along several new profiles should enable us to improve theunderstanding of the geological evolution of this region. The gravity data collectedduring the cruise will be used in Kim’s MS thesis.
Magnetics
Fujiwara will continue the data processing on magnetic anomaly data (both total force
and vector magnetics). Additional figure eight turns will be done for calibration in
Kh05-1 Leg 5 by Okino.
Seismics
Nakamura will process the seismic data at ORI using the “Focus” software.
Rock samples
Samples are distributed to Ohara, Harigane and Yang. Ohara will study thegeochemistry and tectonic interpretation and Harigane will study on rheology. Yang willin charge of age dating. Fujiwara plan to study on rock magnetism.

49

Scheduled cruise
R/V Hakuho-maru KH05-1 Leg5 (additional 1-day mapping in July 2005)
Cruise proposal (to be proposed)
R/V Kairei (2006 or 2007)

List of collaborators other than cruise participants
Dr. Katsuyoshi Michibayashi (supervisor of Yumiko Harigane)
Institute of Geosciences, shizuoka University
e-mail: sekmich@ipc.shizuoka.ac.jp
Dr. Osamu Ishizuka
Institute of Geoscience, geological Survey of Japan / AIST
e-mail: o-ishizuka@aist.go.jp

50

References
Blackman, D.K., J.R. Cann, B. Janssen, and D.K. Smith, Origin of extensional corecomplexes: Evidence from the Mid- Atlantic Ridge at Atlantis Fracture Zone,
Journal of Geophysical Research-Solid Earth, 103 (B9), 21315-21333, 1998.
Christie, D.M., B.P. West, D.G. Pyle, and B.B. Hanan, Chaotic topography, mantle flow
and mantle migration in the Australian-Antarctic discordance, Nature, 394(6694), 637-644, 1998.
Dick, H., and T. Bullen, Chromian spinel as a petrogenetic indicator in abyssal
peridotites and spatially associated lavas, Contributions to Mineralogy andPetrology, 86, 54-76, 1984.
Fujioka, K., H. Fujimoto, A. Nishizawa, T. Sato, A. Koizumi, T. Ohaga, A. Nakamura,and Y. Horii, Southerncross cruise preliminary results: a transect of Palau, Yap
trenches and Ayu Trough at the southern tip of the Philippine Sea plate,
JAMSTEC Journal of Deep Sea Researches, 10, 203-230, 1994.
Fujioka, K., T. Kanamatsu, Y. Ohara, H. Fujimoto, K. Okino, C. Tamura, S.E.
Lallemand, A. Deschamps-Boldrini, J.A. Barretto, N. Togashi, H. Yamanobe,
and A. So, Parece Vela Rift and Central Basin Fault revisited -STEPS-IV(Structure, Tectonics and Evolution of the Philippine Sea) - Cruise summary
report, InterRidge News, 9, 18-22, 2000.
Fujioka, K., K. Kobayashi, T. Fujiwara, H. Kitazato, Y. Iwabuchi, C. Tamura, K. Omori,K. Kato, M. Ariyoshi, and T. Kodera, Tectonics of southern tip of the Philippie
Sea: results of Southerncross '95 cruise, JAMSTEC Journal of Deep Sea
Researches, 12, 275-290, 1996.
Fujiwara, T., K. Fujioka, K. Kobayashi, K. Tamaki, H. Fujimoto, C. Tamura, J. Segawa,Y. Iwabuchi, and A. Nishizawa, Geophysical mapping of the southeasternboundary of the Philippine Sea Plate, EOS Trans. AGU, 77 (46), 1996a.
Fujiwara, T., J. Lin, T. Matsumoto, P.B. Kelemen, B.E. Tucholke, and J.F. Casey,
Crustal evolution of the Mid-Atlantic Ridge near the Fifteen- Twenty Fracture
Zone in the last 5 Ma, Geochemistry Geophysics Geosystems, 4, art. no.-1024,
2003.
Fujiwara, T., C. Tamura, K. Fujioka, and K. Kobayashi, Bathymetric survey around the
Yap-Palau trench-arc system, JAMSTEC Journal of Deep Sea Researches, 12,291-305, 1996b.
Fujiwara, T., C. Tamura, K. Fujioka, and K. Kobayashi, Detailed morphology of the Yap
Trench, JAMSTEC Journal of Deep Sea Researches, 13, 203-218, 1997.
Fujiwara, T., C. Tamura, A. Nishizawa, K. Fujioka, K. Kobayashi, and Y. Iwabuchi,Morphology and tectonics of the Yap Trench, Marine Geophysical Researches,
21 (1-2), 69-86, 2000.
Hawkins, J., and R. Batiza, Metamorphic Rocks of Yap Arc-Trench System, Earth andPlanetary Science Letters, 37 (2), 216-229, 1977.
Iwabuchi, Y., S. Yoshioka, and A. Asada, Submarine topography of the northern end of
Yap Trench, Report of Hydrographic Researches (Hydrographic Department ofJapan), 26, 87-98, 1990.
Kleinrock M.C. and R.T. Bird, southeastern boundary of the Juan Fernandez microplate:
Braking microplate rotation and deforming the Antarctic plate, Journal of51

Geophysical Research, 99, B5, 9237-9261, 1994.
Kobayashi, K., Geological and geophysical investigation of seafloor east of Ogasawara(Bonin) Islands, northern Mariana Trench, Southern Mariana, Yap and Palau
Trench and Arcs, in Preliminary report of the Hakuho-maru Cruise KH84-1, pp.
305, Ocean Research Institute, University of Tokyo, 1985.
Kobayashi, K., Izu-Ogasawara (Bonin), East Mariana Basin and Yap Trench, in In
Preliminary report of the Hakuho-maru cruise KH87-3, Ocean ResearchInstitute, University of Tokyo, 1989.
Kobayashi, K., Origin of the Palau and Yap trench-arc systems, Geophysical JournalInternational, 157 (3), 1303-1315, 2004.
Kroenke, L., and R.B.e.a. Scott, Initial Reports of the Deep-Sea Drilling Project, U.S.
Government Printing Office, Washington, D.C., 1980.
Lee, S.M., Deformation from the convergence of oceanic lithosphere into Yap trenchand its implications for early-stage subduction, Journal of Geodynamics, 37 (1),83-102, 2004.
Lin, J., G.M. Purdy, H. Schouten, J.C. Sempéré, and C. Zervas, Evidence from GravityData for Focused Magmatic Accretion Along the Mid-Atlantic Ridge, Nature,344 (6267), 627-632, 1990.
Martinez, F., J. Karsten, and E.M. Klein, Recent kinematics and tectonics of the Chile
Ridge, EOS Trans. AGU, 79, Fall Meet. Suppl., Abstract F836, 1998.
McCabe, R., and S. Uyeda, Hypothetical model for the bending of the Mariana Arc, in
The tectonic and geologic evolution of southeast Asian Seas and Islands, 2,edited by D.E. Hayes, pp. 281-293, 1983.
Mitchell, N.C., J. Escartín, and S. Allerton, Detachment faults at mid-ocean ridges
garner interest, EOS Trans. AGU, 79, 127, 1998.
Naar, D.F. and R.N. Hey, Tectonic evolution of the Easter Microplate, Journal ofGeophysical Research, 96, B5, 7961-7993, 1991.
Nishizawa, A., K. Okino, and K. Fujioka, Topography of the seaward slope of thecentral Yap Trench, JAMSTEC Journal of Deep Sea Researches, 10, 251-259,
1994.
Ohara, Y., K. Fujioka, T. Ishii, and H. Yurimoto, Peridotites and gabbros from theParece Vela backarc basin: Unique tectonic window in an extinct backarc
spreading ridge, Geochemistry Geophysics Geosystems, 4, art. no.-8611, 2003a.
Ohara, Y., K. Fujioka, O. Ishizuka, and T. Ishii, Peridotites and volcanics from the Yap
arc system: implications for tectonics of the southern Philippine Sea Plate,
Chemical Geology, 189 (1-2), 35-53, 2002.
Ohara, Y., K. Okino, J. Snow, and K.-S.S. Party, Preliminary report of Kairei KR03-01
cruise: amagmatic tectonics and lithospheric composition of the Parece Vela
Basin1, InterRidge News, 12 (1), 27-29, 2003b.
Ohara, Y., T. Yoshida, Y. Kato, and S. Kasuga, Giant megamullion in the Parece Vela
Backarc Basin, Marine Geophysical Researches, 22 (1), 47-61, 2001.
Okino, K., S. Kasuga, and Y. Ohara, A new scenario of the Parece Vela Basin genesis,
Marine Geophysical Researches, 20 (1), 21-40, 1998.
Okino, K., K. Matsuda, D.M. Christie, Y. Nogi, and K. Koizumi, Development ofoceanic detachment and asymmetric spreading at the Australian-Antarctic
Discordance, Geochemistry Geophysics Geosystems, 5, 2004.

52

Okino, K., Y. Ohara, S. Kasuga, and Y. Kato, The Philippine Sea: New survey results
reveal the structure and the history of the marginal basins, Geophysical Research
Letters, 26 (15), 2287-2290, 1999.
Sato, T., J. Kasahara, H. Katao, N. Tomiyama, K. Mochizuki, and S. Koresawa, Seismic
observations at the yap Islands and the northern yap Trench, Tectonophysics, 271,
285-294, 1997.
Searle, R.C., M. Cannat, K. Fujioka, C. Mével, H. Fujimoto, A. Bralee, and L. Parson,
FUJI Dome: A large detachment fault near 64 degrees E on the very slowspreading southwest Indian Ridge, Geochemistry Geophysics Geosystems, 4, art.
no.-9105, 2003.
Seno, T., S. Stein, and A.E. Gripp, A Model for the Motion of the Philippine Sea Plate
Consistent with Nuvel-1 and Geological Data, Journal of Geophysical ResearchSolid Earth, 98 (B10), 17941-17948, 1993.
Shiraki, K., Metamorphic Basement Rocks of Yap Islands, Western Pacific - Possible
Oceanic Crust beneath an Island Arc, Earth and Planetary Science Letters, 13(1), 167-&, 1971.
Smith, W.H.F., and Sandwell, D.T., Global sea floor topography from satellite altimetry
and ship depth soundings. Science, 277, 1956-1962, 1997.
Tomoda, Y., Geological and geophysical investigation of Mariana, Palau, and Yap Arctrenc systems, in Preliminary report of Hakuho-maru cruise KH86-1, pp. 148,
Ocean Research Institute, University of Tokyo, 1986.
Tucholke, B.E., J. Lin, and M.C. Kleinrock, Megamullions and mullion structure
defining oceanic metamorphic core complexes on the mid-Atlantic ridge,
Journal of Geophysical Research-Solid Earth, 103 (B5), 9857-9866, 1998.

53

Appendices

Appendix A; Sound velocity table
Appendix B: List of SeaBeam navigation editing
Appendix C: Dredge logs

Appendix A:

Depth
5
10
20
30
40
50
60
70
80
90
100
120
140
160
180
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1832
1900 
2000
2500
3000
3500

Sound velocity table

Sound Velocity [m/s] used in SeaBeam Survey~2005.6.17~2005.6.20~2005.6.22~2005.6.24
0:48
6:25
5:52
10:30 ~End of survey
1543.51535.61544.41544.91543.91544.01544.01544.51544.51544.1
1544.2
1544.2
1544.41544.61544.31544.31544.2
1544.51544.81544.41544.51543.81544.11545.01544.41544.51543.51544.11545.11543.31543.51543.61543.61544.71543.01542.51542.71543.1
1544.01541.51542.11541.51542.71542.21540.11540.91540.31541.31540.31538.71540.4
1538.01540.41537.41535.6
1534.01533.6
1536.21531.21528.81523.11530.41529.91522.91521.41519.41525.61523.31517.21516.31516.11518.21517.21512.51512.71510.91511.41514.51505.41511.51495.11495.01493.01493.6
1493.61490.41490.71488.81490.91489.01489.01488.01486.31487.51487.31489.01486.51485.61486.81487.01489.21486.11485.01486.01487.81487.61486.01484.61485.11487.61486.71485.91484.51484.51486.81486.71485.51484.51484.81486.41486.71485.71484.71485.21485.81486.41486.41484.81485.01485.31486.51486.51484.91485.41485.81486.91486.91485.41485.91486.51487.31487.31486.11486.41487.11487.91487.91487.21487.11487.91488.81488.81488.31488.51488.81489.81489.81489.71489.81489.41490.01490.0 
1490.11489.9
1490.8 
1491.41491.41491.41491.41491.41498.31498.31498.31498.31498.31506.41506.41506.41506.41506.41514.51514.51514.51514.51514.5

4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
9000

1523.21523.21523.21523.21523.21532.11532.11532.11532.11532.11541.11541.11541.11541.11541.11550.11550.11550.11550.11550.11559.11559.11559.11559.11559.1
1568.2
1568.2
1568.2
1568.2
1568.21577.4
1577.4
1577.4
1577.4
1577.4
1586.6
1586.6
1586.6
1586.6
1586.61595.81595.81595.81595.81595.81605.01605.01605.01605.01605.01614.31614.31614.31614.31614.3
XBT-2 (yellow) XBT-1(yellow) XCTD-2(blue) XBT-3 (yellow) XBT-4 (yellow)
Levitus (white) XCTD-1(blue) Levitus (white) Levitus (white) Levitus (white)Levitus (white) Appendix B: List of SeaBean navigation editng
SeaBeamFileName

start timeend time

comments

sb200506161809.mb44

2005/06/16 18:11:18

2005/06/16 18:36:27 not used (figure eight turn)sb200506170039.mb44

2005/06/17 00:41:30

2005/06/17 00:50:18 not used (no sound velocity correction)

sb200506172148.mb44

2005/06/17 21:50:37

2005/06/17 22:37:32 navigation edited (bad heading, use COG)

sb200506172235.mb44

2005/06/17 22:37:32

2005/06/17 22:47:48 not used (bad heading)

sb200506272306.mb44

2005/06/17 23:03:08

2005/06/17 23:22:50 not used (bad heading)

sb200506172321.mb44

2005/06/17 23:23:10

2005/06/18 00:09:37 navigation edited (bad heading, use COG)

sb200506182329~06190059.mb44

2005/06/18 23:31:29

2005/06/19 01:24:02 not used (deploying air gun, slow speed)

sb200506201959.mb44

2005/06/20 20:01:12

2005/06/20 20:29:44 navigation edited (bad heading, use COG)

sb200506220546~06220609.mb44

2006/06/22 05:48:29

2005/06/22 06:31:02 not used (figure eight turn)navigation edited (bad heading, use COG,

sb200506220815~06220845.mb44

2005/06/22 08:17:15

2005/06/22 09:12:48 cut 9:01-9:07)
navigation edited (bad heading, use COG,

sb200506221415~06221510.mb44

2005/06/22 14:17:26

2005/06/22 15:38:44 cut 14:29-14:34, 15:27:20-15:30:0)
navigation edited (bad heading, use COG,

sb200506221603.mb44

2005/06/22 16:04:51

2005/06/22 16:29:32 cut 16:13-16:15:30)

sb200506232020~06232044.mb44

2005/06/23 20:21:37

2005/06/23 21:03:50 not used (dredge, slow speed)

sb200506240623~06240637.mb44

2005/06/24 06:24:31

2005/06/24 06:38:46 not used (dredge, sow speed)

1Appendix C
Station : KH05-01-Leg 3-D1

Date : June 24, 2005

Weather : Fine-cloudy

Sea state : Calm

Target water depth (m) : 4500 m

Target position (Lat., Lon.) : 9°17.67', 135°55.83'
Description of the target : southern-facing escarpment of a hook-shaped deep
Dredged assembly employed : Chain-bag dredge + two pipe dredges + 200 kg weight
Watch stander : Yasuhiko Ohara, Yumiko Harigane and Shin'ichiro Yokogawa
Comment : None
Wire length (m)Tension (t)

7:22

0

-

Water depth
(m)
4502

7:34

300

-

4481

Time (local)-

Current
direction (deg)---Heading (deg)

Lat.

Note

Lon.

-

-

9°17.52'

135°55.81'

8:26

3100

3.60

4411

-

-

-

-

8:35

3569

4.08

4461

-

-

9°17.63'135°55.82'

Deploy dredge

8:40

4003

4.58

4388

-

-

-

-

8:50

4500

5.20

4333

70.0

267.1

9°17.69'

135°55.85'

8:53

4537

4.44

-

-

-

-

-

Wire stop; Start 50 m wire-out at wire speed 0.3 m/sec
On bottom

8:54

4550

4.42

4292

75.3

267.6

-

-

Wire stop; Finish 50 m wire-out

9:01

4550

4.48

4278

60.5

267.4

9°17.71'

135°55.85'

9:09

4550

4.90

4220

65.0

267.7

9°17.77'

135°55.88'

9:11

4550

5.16

4161

59.7

269.0

9°17.87'

135°55.93'

9:20

4550

5.36

4150

65.0

264.5

9°17.90'135°55.94'

9:23

4562

4.54

4111

58.0

263.3

9°18.00'

135°56.00'

Start 50 m wire-out at wire speed 0.3 m/sec

9:26

4600

4.48

4092

57.8

270.9

9°18.05'

135°56.03'

Wire stop; Finish 50 m wire-out; Ship speed 1.7 knot

9:29

4600

4.76

4066

58.2

268.5

9°18.09'135°56.05'

9:31

4600

5.12

4052

-

-

9°18.14'135°56.08'

Ship speed 1 knot
Ship speed 1.6 knot

2Time (local)

Wire length (m)Tension (t)

9:34

4600

5.66

Water depth(m)-Heading (deg)-Current
direction (deg)
-

Lat.

Lon.

-

-

9:37

4600

5.74

-

-

-

-

-

9:39

4600

5.60

-

-

-

-

-

9:44

4600

6.66

3938

65.2

269.0

9°18.33'

135°56.17'

9:50

4600

5.78

-

-

-

-

-

Note

Max tension 1

9:52

4600

5.82

-

-

-

-

-

9:53

4600

5.98

-

-

-

-

-

9:53

4600

6.52

3883

55.3

275.1

9°18.46'

135°56.24'

9:56

4600

5.72

-

-

-

-

-

9:58

4600

6.18

-

-

-

-

-

9:59

4600

5.02

3866

60.0

269.3

9°18.52'

135°56.27'

10:05

4516

5.04

3837

70.7

284.8

9°18.58'

135°56.30'

10:06

4516

5.98

-

-

-

-

-

10:07

4516

6.42

-

-

-

-

-

10:09

4516

6.28

-

-

-

-

-

10:15

4375

5.00

3838

66.8

274.9

9°18.61'

135°56.32'

Change amplitude of wire length meter

10:27

4209

5.06

3795

61.8

256.7

9°18.72'

135°56.41'

Off bottom; Change wire speed from 0.2 m/sec to 0.3 m/sec

10:32

4115

4.90

3634

-

-

9°18.77'

135°56.44'

10:37

4020

4.86

3622

61.5

262.7

9°18.81'135°56.46'

10:47

3710

4.60

3606

61.8

263.9

9°18.90'135°56.49'

10:51

3600

4.54

3601

-

-

9°18.94'

135°56.51'~ 12:00

-

-

-

-

-

-

-

Max tension 2
Max tension 3
Start 50 m wire-out at wire speed 0.2 m/sec

Change wire speed from 0.3 m/sec to 0.5 m/sec
Change wire speed from 0.5 m/sec to 1.0 m/sec
Dredge on deckAppendix C
Station : KH05-01-Leg 3-D2

Date : June 24, 2005

Weather : Fine

Target position (Lat., Lon.) : 9°06.95', 136°23.15'

Sea state : Calm

Target water depth (m) : 4900 m

Description of the target : noutheastern-facing flank of hook-shaped abyssal hill
Dredged assembly employed : Chain-bag dredge + two pipe dredges + 200 kg weight
Watch stander : Yasuhiko Ohara, Yumiko Harigane and Shin'ichiro Yokogawa
Comment : 1st fuse wire (6 mm diameter), 25 cm long at the chain-bag dredge was broken.

16:42

0

-

Water depth
(m)
-

-

Current
direction (deg)
-

-

-

17:03

532

1.08

4893

93.5

268.9

9°06.93'

136°23.17'

Wire length meter start operating

18:15
18:16
18:19
18:22
18:23
18:29
18:32

4838
4850
4900
4920
4937
4937
4986

5.56
5.62
5.62
4.90
4.92
4.90
4.84

4896
4889
4894
4893
4891
4858
4847

80.2
79.8
90.8
100.5
109.3
117.5
102.8

277.3
262.1
272.1
256.3
276.4
266.3
267.6

9°06.90'9°06.90'9°06.89'
9°06.88'9°06.73'

136°23.17'
136°23.17'
136°23.18'
136°23.17'
136°23.14'

Change wire speed from 0.3 m/sec to 0.1 m/sec
Wire stop; Start 50 m wire-out at wire speed 0.2 m/sec
Wire stop; Start 50 m wire-out at wire speed 0.3 m/sec
On bottom
Wire stop
Wire stop; Start 50 m wire-out at wire speed 0.3 m/sec
Wire stop; Ship speed 1.3 knot

Time (local)

Wire length (m)Tension (t)Heading (deg)

Lat.

Note

Lon.

18:44

4986

4.94

4665

116.2

262.1

9°06.55'

136°23.14'

18:51

4986

5.46

4620

115.7

264.5

9°06.44'

136°23.13'

18:55

4986

5.56

4588

113.2

260.0

9°06.39'136°23.13'

19:03

4986

5.46

4548

112,2

270.6

9°06.26'

136°23.15'

19:08

4900

5.72

4520

114.8

264.2

9°06.17'136°23.16'

19:10

4867

5.58

4500

115.3

269.7

9°06.14'136°23.15'

Deploy dredge

Start 50 m wire-in at wire speed 0.2 m/sec
Wire stop

19:204867

5.52

Water depth
(m)
4471

112.0

Current
direction (deg)271.1

9°06.00'

136°23.15'

19:22

4872

8.80

4470

113.8

269.7

9°05.97'

136°23.15'

19:23

4893

5.72

4472

112.8

272.0

9°05.95'

136°23.15'

19:25

4915

5.92

4478

113.2

270.0

9°05.93'

136°23.16'

Time (local)

Wire length (m)Tension (t)Heading (deg)

Lat.

Note

Lon.
Max tension 1; wire-out

In order to leave the bottm, change heading to left; Reduceship speed
Wire stop

19:28

4912

5.46

4477

80.7

267.9

9°05.92'

136°23.15'

19:29

4902

5.90

4476

79.5

266.3

9°05.93'

136°23.15'

Start wire-in

19:30

4900

7.92

-

-

-

-

-

Wire stop

19:33

4898

7.38

-

-

-

-

-

19:34

4895

-

-

-

-

-

-

Start wire-in at wire speed 0.2 m/sec
Wire stop

19:36

4884

6.70

4467

64.8

270.0

9°06.00'

136°23.19'

19:37

-

8.88

4483

-

-

-

-

Max tension 2 ; Fuse wire break?

19:39

-

6.32

-

-

-

-

-

Start wire-in at wire speed 0.2 m/sec

19:41

4862

8.86

-

-

-

-

-

19:42

4857

5.90

4500

-

-

-

-

Max tension 3
Off bottom?

19:43

4835

5.50

4502

57.5

269.6

-

-

Change wire speed from 0.2 m/sec to 0.3 m/sec

19:52

4686

5.60

4511

84.2

264.2

9°06.14'136°23.15'

Change wire speed from 0.3 m/sec to 0.5 m/sec; Off bottom

19:57

4509

5.58

4508

84.5

269.0

9°06.15'136°23.14'

Change wire speed from 0.5 m/sec to 1.0 m/sec; Start wire-in

20:22

-

-

-

-

-

-

-

Start wire-in

Dredge on deck