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R/V Natsushima Cruise Report

NT15-15

Off Tanegashima, southwestern Japan

Biogeochemical and geomicrobiological investigations of

submarine mud volcano off Tanegashima, southwestern Japan

-implication for research on the potential of huge hydrocarbon

resources-

Aug.12,2015-Aug.17,2015

Japan Agency for Marine-Earth Science and Technology

(JAMSTEC)

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●Contents 1. Cruise Information

2. Researchers

3. Observations

3.1 Background

3.2 Objective

3.3 List of observation equipment

3.4 Research results

4. Notice on Using

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1. Cruise Information ● Cruise ID NT15-15

● Name of vessel: R/V Natsushima

● Title of the cruise: Biogeochemical and geomicrobiological investigations of submarine mud

volcano off Tanegashima, southwestern Japan

-implication for research on the potential of huge hydrocarbon resources-

●Title of proposal: Biogeochemical and geomicrobiological investigations of submarine mud

volcano off Tanegashima, southwestern Japan

-implication for research on the potential of huge hydrocarbon resources-

● Cruise period: Aug.12,2015-Aug.17,2015

● Ports of departure: Kagoshima, Kagoshima prefecture / arrival: Naha, Okinawa prefecture

● Research area: Off Tanegashima, southwestern Japan

● Research Map

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Fig. 1 Cruise truck of the NT15-15 cruise

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2. Researchers Chief scientist Akira Ijiri (JAMSTEC) Representative of Science Party Akira Ijiri [JAMSTEC]

Associate chief scientist Fumio Inagaki (JAMSTEC) Scientist Hideaki Machiyama (JAMSTEC)

Scientist Yuki Morono (JAMSTEC)

Scientist Yuka Masaki (JAMSTEC)

Scientist Nan Xiao (JAMSTEC)

Marine Technician Yuji Fuwa (NME Ltd)

3. Observations 3.1 Background

Submarine mud volcanoes occur along the margins of convergent plates and are formed by the

vertical intrusion of low density, deformable sediments from the deep subsurface to the seafloor (Milkov,

2000; Kopf, 2002). The common geochemical characteristics of submarine mud volcanoes are

diagenetically altered pore fluid by dehydration of clay mineral and presence of hydrocarbon gases

derived from thermocatalyte decomposition of sedimentary organic matter (Ijiri, 2009). These

characteristics suggest that the mud volcano fluid must originate at a deep depth in the sedimentary layer

where these chemical reactions typically occur (>60˚C). The mud volcanoes are, therefore, important

pathway of deep sourced materials, especially natural source of methane, which is one of the green house

gases, to hydrosphere and atmosphere (Milkov, 2000; Kopf, 2002).

Several ten mud volcanoes have been found Island have been found off Tanegashima along the

Ryukyu Trench (Ujiié, 2000). During 2012-2014, our research group (Geobio-Engineering and

Technology Group, Research and Development Center for Submarine Resources), had conducted

submarine topography survey to clarify the spatial distribution of mud volcanoes off Tanegashima. In

these cruises, we observed mud flow from the top of mud volcano No. 1 (MV#1) (30˚53´N, 131˚46´E・

water depth: 1536 m) by side scan sonar image. At MV#1, one piston core was retrieved on 2002.

However, newly erupted mud was not reported (Nakaya et al. 2010). Thus, the mudflow possibly

indicates recent eruption of the mud volcanoes after 2002. Because relatively large earthquakes (M4-M5)

were observed after 2002, the mudflow may be related with these earthquakes. Furthermore, if we take

the mud sample from the top of MV#1, we can get fresh sediment directly supplied from deep realm of

the mud volcano.

Reerences

1. Milkov, A. V. (2000) Worldwide distribution of submarine mud volcanoes and associated gas

hydrates. Mar. Geol. 167, 29–42.

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2. Kopf, A. J. (2002) Significance of mud volcanism. Rev. Geophys. 40, 1005,

doi:10.1029/2000RG000093.

3. Ijiri, A. (2009) Origin of fluid in submarine mud volcanoes. J. Geography, 118, 435–454 (in Japanese

with English abstract)

4. Nakayama et al. (2010) Source of pore water in a Tanegashima mud volcano inferred from chemical

and stable isotopic studies. Geochem. J. 44, 561–569.

3.2 Objective

The objectives of this cruise are investigation of 1) eruption history, activity of eruption, and

origin of mud fluid of MV#1, and 2) biogeochemical processes sustained by the supply of deep origin

materials associated with mud volcanism.

3.3 List of observation equipment

(1) Pressure Corer

This coring system allows retrieving sediment core samples without releasing the in situ hydrostatic

pressure (max. 50 MPa) during core recovery.

Fig.2 Photo of pressure corer.

(2) Push corer

(3) Niskin sampler

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(4) Water temperature recorder (ANTARES)

Serial# 1854306 Depth rating 6000 m Material of pressure case stainless steel Length 160 mm Diameter 15 mm Number of thermistor 1 Accuracy < +/- 0.1 °C

Sampling interval 10 min

Measurement start August 14, 2015 08:00:00

Total weight *1 10.8 kg in air and 8.6 kg in seawater

*1 The value of total weight includes weight values of a platform

Fig. 3 Schematic figure and photo of water temperature recorded.

Deployment of bottom-water temperature monitoring systems

In heat flow measurement in shallow sea area, bottom-water temperature variation (BTV) with

large amplitude prevents to measure accurate temperature gradient with a geothermal probe. For future

measurement of geothermal gradient (hence heat flow), we deployed bottom-water temperature

monitoring systems to obtain long-term bottom-water temperature data for removal of the effects of BTV

from measured sub-bottom temperatures.

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3.4 Research results

○ Dive summary

In NT15-15 cruise, we conducted two dives (#1866 and #1867) of Hyper-Dolphin on 14 Aug

2014 (Fig. 3).

During the #1866, the ROV landed on near the summit of the MV#1 and surveyed around the

summit. We found out a small colony of Calyptogena (Fig. 4). Near the Calyptogena colony, we retrieved

sediment samples by using push corer. We also tried to take pressure-conserved sediment by using

pressure corer. But the pressure was not conserved probably because of leak from valve. The

hemi-pelagic sediment was not observed around the summit. Instead of that, several consolidated sandy

mudstone clasts (several cm to several ten cm) were observed (Fig. 5). Such clasts are probably mixed

with fractured sediments by diapiric mud intrusion. This suggests that the sediment around the summit is

composed erupted mud and not covered by hemi-pelagic sediments. Some clasts were taken to determine

their origin and age.

At second dive #1867, the ROV landed near the western foot of MV#1. The ROV climbed along

a gully and reached to the summit. At the Calyptogena colony, we took living Calyptogena as well as their

shell. Near the colony, we tried to retrieve pressure core (Fig. 2) and succeeded in the sampling.

Fig. 3 HD track during #1866 (red circle) and # 1867 (green circle)

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Fig. 4 Photo of Calyptogena colony found at the summit.

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Fig. 5 Photo of Sandy mudstone clasts.

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○ Cruise log

Date Local

Time

Note Position/Weather/Win

d/Sea condition

12-Aug-15 Sail out & started NT15-15. 8/12 12:00 (JST)

09:00 Let go all shore lines & left Kagoshima port for

Research Area.

Kagoshima bay

9:20 -

9:45

Carried out shipboard education & training for

scientists.

31-06.0N, 130-38.0E

13:00 Proceeded to west of tanegashima due to

research area is rough sea.

Cloudy

21:15 Arrived at west of tanegashima. SSW-6 (Strong

breeze)

4 (Moderate)

1 (Low swell short or

average)

Visibly: 6'

13-Aug-15 Avoided rough sea at west of tanegashima

and Carried out MBES survey.

8/13 12:00 (JST)

13:00

-

13:30

Scientists meeting. West of tanegashima

17:30 Proceeded to research area. 30-15.0N, 130-45.0E

22:30 Arrived at research area. Fine but Cloudy

22:41 Rereased XBT at <30-45.8322N,

131-32.8355E>

WSW-5 (Fresh

breeze)

23:18 Started MBES mapping survey. 4 (Moderate)

2 (Low Swell Long)

Visibly: 8'

14-Aug-15 Operation "HPD" Dive#1866 and #1867 8/14 12:00 (JST)

04:23 Finished MBES mapping survey. Off east of

tanegashima

10:30 Arrived at dive point. 30-53.0N, 131-46.0E

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11:16 Hoisted up HPD Cloudy

11:20 HPD Launched. West-4 (Moderate

breeze)

11:32 HPD dove and started her operation #1866. 3 (Slight)

12:42 HPD landed on the sea bottom (D=1418m). 1 (Low swell short or

average)

14:10 HPD left the sea bottom (D=1417m). Visibly: 6'

14:50 HPD floated.

15:06 Recovered HPD and finished her operation.

16:42 Hoisted up HPD

16:46 HPD Launched.

16:58 HPD dove and started her operation #1867.

18:09 HPD landed on the sea bottom (D=1683m).

20:56 HPD left the sea bottom (D=1417m).

21:36 HPD floated.

21:52 Recovered HPD and finished her operation.

23:00 Started MBES mapping survey.

15-Aug-15 Freefall of umbilical cable 8/15 12:00 (JST)

03:57 Finished MBES mapping survey and then

proceeded to freefall area.

Off south west of

tanegashima

12:45 Arrived at freefall area. 29-36.0N, 131-24.0E

13:14 Started freefall of umbilical cable. Cloudy

16:40 Finished freefall of umbilical cable. WSW-3 (Gentle

breeze)

16:41 Started freefall of umbilical cable. 2 (Smooth)

19:52 Finished freefall of umbilical cable. 1 (Low swell short or

average)

20:00 Proceeded to Naha port. Visibly: 7'

16-Aug-15 Proceeded to Naha port. 8/16 12:00 (JST)

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17-Aug-15 Disembarkation scientist group & completed

NT15-15

09:00 Arrived at Naha port. Then completed NT15-15.

○ Dive information

Dive log #1866

Dive Log of

HPD Dive #1866

2015/

08/14

Time

(JST)

Dep.

(m)

Alt.

(m)

Head

(Deg)

Pos.

Xm

Pos.

Ym

Description Rema

rks

12:41 1414 3.6 278 -89.7 388.7 Niskin (green) close

12:42 1418 0 275 -86 385.4 Arrived to bottom

12:59 1428 0.5 58 7.5 294.5 arrived event mark#14

13:02 1428 0.5 58 7.5 294.5 Rock sampling (R1)

13:15 1424 3.4 174 4.2 463.3 Change direction to south, head to event

#15

13:18 1423 1.2 172 -34.2 464.1 Gap structure was observed (260 degree)

13:20 1422 0.6 240 -53.9 467.6 Head to event #1

13:22 1419 0 237 -75.1 434.8 Wood chips were observed

13:28 1414 2.8 241 -97.2 376.2 Niskin (red) closed

13:33 1417 0 207 -96.8 379 MBARI Red LONG sampling (with hole)

13:36 1417 0 207 -96.8 379 MBARI White LONG sampling

13:43 1417 0 198 -71.4 377.1 Pressure coring start

13:59 1417 0 198 -71.4 377.1 Pressure coring done

14:03 1417 0 198 -71.4 377.1 H1866-1 marker dropped

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14:05 1417 0 196 -102.7 364.3 Temperature sensor deployed (H1866)

14:10 1417 0 196 -102.7 364.3 Left bottom

Dive log #1867

Dive Log of

HPD Dive #1867

2015/

08/14

Time

(JST)

Dep.

(m)

Alt.

(m)

Head

(Deg)

Pos.

Xm

Pos.

Ym

Description Rema

rks

18:08 1683 2.5 118 355.7 -710 Arrived bottom, headed to #2 point

18:30 1639 0.5 124 230.6 491.6 Landed, sampling rock R1

18:40 1639 0.5 124 230.6 491.6 Headed to #3

18:57 1572 3.5 151 121.1 -230.1 Obsevation, Sampling rock R2 (two

pieces)

19:14 1535 0 110 49.2 -109.6 Sampling rock R3

19:25 1469 0 95 9.3 67.7 Sampling rock R4

19:40 1421 1.3 177 -55.6 274.5 Observation of Gap

19:45 1429 2 29 -197.

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288.7 Head to #1

19:52 1419 0 40 -115 367.3 remove mud

20:03 1418 0 41 -94.2 366.1 Landed, pressure coring start

20:35 1418 0 41 -94.2 366.1 Pressure coring done

20:39 1418 0 41 -94.2 366.1 MBARI coring (red)

20:41 1418 0 41 -94.2 366.1 MBARI coring (white)

20:54 1418 0 41 -94.2 366.1 Bio-sampling (mussel)

20:56 1418 0 41 -94.2 366.1 Left bottom

Include any information that may be necessary for analysis and QC planning and secondary use

(publications, provisions, etc.)

4. Notice on Using This cruise report is a preliminary documentation as of the end of the cruise.

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This report may not be corrected even if changes on contents (i.e. taxonomic classifications) may be

found after its publication. This report may also be changed without notice. Data on this cruise report may

be raw or unprocessed. If you are going to use or refer to the data written on this report, please ask the

Chief Scientist for latest information.

Users of data or results on this cruise report are requested to submit their results to the Data Management

Group of JAMSTEC.