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Preliminary Report on

KR11-12 Cruise in the Nankai Trough off Muroto

Dec. 20 – Dec. 25, 2011 Yokosuka – Harumi

Masataka Kinoshita (IFREE-JAMSTEC) and KR11-12 Shipboard Science Party

DISCLAIMER

This cruise report is a preliminary documentation as of the end of the cruise. This report may not be corrected even if changes on contents are 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.

Acknowledgments The science party would acknowledge that the KR11-12 cruise involved very difficult operations which were only made possible by the professional skill of the following persons: Captain Mr. Ishiwata, Chief Officer Mr. Aoki and KAIREI marine crew for overall support, including ship navigation, KAIKO launching/recovery operation, and ship’s life; Chief ROV Operator Mr. Nambu and KAIKO Operation Team for KAIKO operation, including hovering during data retrieval at 1173B and 808I, JAMSTEC Marine Operation Department for cruise logistics, and Mr. Onodera with Nippon Marine Enterprises, Co. Ltd. for technical support.

Table of Contents

1. Introduction

2. Explanatory Notes

2.1. KAIREI

2.2. KAIKO 7000II

2.3. ACORK (Kinoshita)

2.4. Composite gas-tight fluid sampling system (Miyazaki / Hulme / Kinoshita)

3. Dive Summary

3.1. Dive 525

3.2. Dive 526

3.3. Dice 527

4. Preliminary data and post-cruise research plan

4-1. Summary of ACORK results

4-2. Pore fluid geochemistry

4-3. Microbiology

4-4. Flow meter measurements of ACORK venting

4-5. Sub-bottom profiling and side-scan-sonar record (Kinoshita)

Abstract Three dives were completed using ROV ‘KAIKO’ onboard R/V KAIREI during Dec. 20-25, 2011, in order to retrieve the pressure data and the interstitial fluid samples from ACORKs at ODP Holes 808I and 1173B deployed in the Nankai Trough off Muroto. With a 3-year-long and a 4-year-long new data from 808I and 1173B, respectively, we now have 11.5-year-long continuous pressure records since June 2001 at both sites. Most of pressure data from multiple depths show constant values with tidal signals throughout the period. Transient changes were only observed at the time of nearby earthquakes. During the recent 3 to 4 years, a spiky anomaly was detected at the time of Mar. 11 Tohoku earthquake. Gas-tight fluid sampling was successfully carried out from the hydraulic port attached to the awellable packer inserted within the ACORK head. We observed the fluid was shimmering from the port, and the flow rate was successfully measured using a ball-type flowmeter. We also confirmed that closing the valve at the hydraulic port shut down this flow. However, we could not confirm any significant pressure change in the lowermost pressure data after the valve closure.

Cruise Information Cruise ID KR11-12

Name of vessel R/VKAIREI

Title of the cruise ACORK2011

Chief Scientist/PI Masataka Kinoshita (JAMSTEC)

Title of proposal Understanding characteristics and interseismic deformation within the toe of

accretionary prism through borehole hydrologic monitoring

Cruise period Dec. 20-25, 2011

Ports of call Yokosuka – Harumi, Tokyo

Research area Nankai Trough off Muroro

1．Introduction Two Advanced CORKs (ACORKs) were installed in the frontal thrust and on the trough floor of the Nankai Trough off Muroto during the ODP Leg196 in 2001 (Mikada et al., 2002; Figs. 1.1 – 1.3). Since then, data was retrieved basically once per year by ROV KAIKO or HOV Shinkai 6500 (both from JAMSTEC). The downhole pressure data have been continuously recorded since the installation of ACORK in 2001 at Hole 808I (frontal thrust site) and at Hole 1173B (trough floor). Davis et al. (2006) reported a transient pressure increase in July-2003, and interpreted that it was caused by a series of very-low-frequency events in the accretionary prism.

Because of incomplete installation of ACORK at 808I, its top 40m part could not be inserted in the borehole and was forced to lay down on the seafloor. As such, the bridge plug which should isolate the lowermost section in the decollement could not be installed during the drilling operation, so that S1 pressure data remain identical with those on the seafloor. Earl Davis built another bridge plug to be inserted horizontally into the ACORK head on the seafloor, and it was attempted to insert during the KR03-05 KAIKO cruise in 2003. However, we have had bad luck of losing (old) KAIKO vehicle and could install the bridge plug during that cruise. Two more cruises in 2004 and 2006 were spent to complete this operation but we could not do it (Table 1.1). In 2007, we set a bridge plug (inflatable packer) into the mouth of ACORK head at ODP Hole 808I surging the KR07-18 cruise, in order to seal off the lowermost pressure port in the decollement. The result, however, was not satisfactory. From the data recovered during KR08-13 cruise in 2008, we found no change in the lowermost pressure after the packer deployment. We then removed the bridge plug and replaced with a new, swellable packer into the casing. We expected to recover data in 2009, but the KR09-12 cruise could not retrieve any data because of typhoon evacuation, etc.

In 2011, we were finally able to revisit both sites. This document reports preliminary results of the cruise KR11-12.

Table 1.1 List of research cruises related to Nankai ACORK

Cruise Period Chief Sci. Platform Mission & achievements ODP Leg196

2001 Mikada/Becker JOIDES Resolution

ACORK Installation

KR02-10 2002 Mikada Kairei/KAIKO Data download KR03-05 2003 Mikada Kairei/KAIKO Data download & Deploy BP YK04-05 2004 Kinoshita Shinkai 6500 Data download / BP set not completed / recover

BP KR06-10 2006 Kinoshita KAIKO 7000II Data download / BP not launched KR07-18 2007/12/

16-26 Kinoshita KAIKO 7000II Data download / Remove mud / set BP

KR08-13 2008/10/5-14

Kinoshita KAIKO 7000II Data download / Remove BP / Set swellable packer

KR09-12 Kasaya KAIKO 7000II Observe shimmering from 808I hydraulic port KR11-12 2011/12/

20-25 Kinoshita KAIKO 7000II Data download / fluid sampling from 808I /

SSS/SBP across the frontal thrust Note: ‘BP’ stands for the bridge plug.

Fig. 1.1 Index map showing the dive locations (808I and 1173B) .

Fig. 1.2 Location of ACORK sites 808I and 1173B. Stars indicates spicenter of very low frequency events in 2003 (Ito and Obara, 200#).

Fig. 1.3 Location, schematic diagram and photos of ACORK at 808I and 1173B.

Shipboard Personnel Chief Scientist Masataka Kinoshita (IFREE/JAMSTEC) Shipboard Scientists Junichi Miyazaki (BIOGEOS/JASMTEC) Samuel Hulme (Moss Landing Marine Laboratories) Science/Operation support staff Takuya Onodera (Nippon Marine Enterprise) Kairei Crew

Captain: MASAYOSHI ISHIWATA

Chief Officer: TAKAFUMI AOKI

2nd Officer: TAKESHI EGASHIRA Junior 2nd Officer: KAZUKI MIYAKE

3rd Officer: YUMIHIKO KOBAYASHI Junior 3rd Officer: KAZUKI KUMANO

Chief Engineer: KIYONORI KAJINISHI

1st Engineer: KOJI FUNAE

2nd Engineer: KENICHI SHIRAKATA

3rd Engineer: YOSHIHIRO OTSUGA

Chief Electronics Operator: YOICHI INOUE

2nd Electronics Operator: MICHIYASU KATAGIRI

Boat Swain: YOSHIAKI KAWAMURA

Able Seaman: TAKAO KUBOTA, YUKITO ISHII, YOSHIAKI MATSUO

Sailor: SHINSUKE UZUKI, TORU NAKANISHI, RYOMA TAMURA

No1. Oiler: MASARU KITANO

Oiler: KATSUYUKI MIYAZAKI, YOSHINORI KAWAI Assistant Oiler: TAIJUN IWAO, TORU HIDAKA

Chief Steward: ISAO MATSUMOTO

Steward: SHINSUKE TANAKA, YOSHIO OKADA, KIYOTAKA KOZSUJI,

SHIHO SHIMIZU

KAIKO Operation team Chief ROV Operator: YOSHINOBU NAMBU

ROV Operator: UEKI MITSUHIRO, ATSUMORI MIURA,

KIYOSHI TAKISHITA, TOMOE KONDO, SHIGETAKE SEIJI, RYU ASAI,

SHOTA IHARA

2. Explanatory Notes 2-1. KAIREI

全長： 104.9m 幅： 16.0m 喫水： 4.5m 総トン数： 4,628 トン速力： 16.7 ノット航続距離：約 9,600 海里（約 17,800km）主推進機関：ディーゼル機関 2 基×2,206kW×600rpm 推進システム：可変ピッチプロペラ 2 軸バウスラスタ

乗組員： 60 名 (乗組員 29 名・研究者等 31 名)

建造年： 1997 年建造造船所：川崎重工業(株)坂出工場運航会社：日本海洋事業(株)

2-2. KAIKO 7000II

「かいこう７０００Ⅱ」の主要項目

方式：有索中継機方式、遠隔操作自航

（ランチャー方式）最大潜航深度： 7000m

ランチャービークル長さ： 5.2m 2.8m

幅： 2.6m 2.5m 高さ： 3.2m 2.0m 空中重量： 5.8 トン 2.9 トン水中重量： 3.8 トン 0 トン

2.3. ACORK (Kinoshita) Two Advanced CORKs (ACORKs) were installed during Leg 196 to provide

long-term in-situ pressure records in the Nankai Trough. The ACORKs were an important advance over the simple CORK hydrogeological observatories successfully installed in many other ODP locations since 1991 (Figure 1). Objectives of these long-term installations range from assessing background state of formation fluids to detecting deformation-induced transients to constraining elastic and hydrologic properties of the subsurface from tidal loading signals.

The original CORKs have a single seal at the seafloor and therefore integrate hydrogeologic signals over the entire drilled interval beneath the seal, whereas the ACORK has multiple seals and monitoring intervals in a single borehole to allow pressure measurements at isolated stratigraphic intervals. Prior CORK results and the ACORK concept are described in more detail in a workshop report (Becker and Davis, 1998) and in several summary articles (e.g., Becker and Davis, 2000; Davis and Becker, 2001; Becker and Davis, 2005).

Table 1 shows the ACORK channel assignment. On both sites, SF stands for seafloor pressure, S1 the deepest interval, and S5 (S6) the shallowest interval. Table 2 shows the history of data retrieval since 2002.

ACORK at Hole 808I The ACORK at Site 808I has two packers and six screens and was intended to penetrate the decollement. Due to poor drilling conditions and failure of the underreamer, actual penetration concluded ~36 meters short of the goal of 964 mbsf. The ACORK head therefore extended 42 meters above the seafloor, and the casing string could not support its own weight. Upon removal of the drill string, the ACORK slowly tipped within seconds. Careful video inspection showed the casing to be bent but not broken. Fortuitously, the ACORK head tipped in the best possible direction—the ACORK rests on its side with logger bay and sample ports facing upward.

Principal observation zones at Site 808I include the Lower Shikoku Basin formation at several depths above the decollement, the overlying Upper Shikoku Basin formation, and the Outer Marginal Trench-Wedge facies near the frontal thrust (Figure 2).

ACORK at Hole 1173B

The ACORK at ODP Site 1173B has four packers and five screened monitoring intervals. It was successfully installed to 728 meters below seafloor (mbsf). A bridge plug was installed to isolate the deepest screen from pressure at the seafloor via the open casing. During deployment, the bridge plug set prematurely at approximately 466 mbsf. The rig floor did not sense the bridge plug setting, and the drill pipe broke off at the ACORK head. A video inspection at the end of Leg 196 confirmed that the drill pipe broke off precisely at the ACORK head and that the ACORK head suffered no damage, and data show that the bridge plug seated properly. Unfortunately, the broken drill pipe prevented installation of a thermistor cable supplied by JAMSTEC.

Principle observation zones at Site 1173 include oceanic basement below 731 mbsf, the Lower Shikoku Basin formation below the stratigraphic projection of the

decollement, and the stratigraphic projection of the decollement within the upper section of the Lower Shikoku Basin formation (Figure 2).

The ACORK head is a 30" diameter cylindrical frame fabricated from 3/8" steel around a section of 11-3/4" casing. In three separate bays, the ACORK head houses: 1) the sensor/logger/underwater-mateable connector assembly, 2) the spool valves and sampling valves and ports, and 3) the three-way pressure sensor valves and geochemical sampling valve and port (Becker and Davis, 2005). At the top of the ACORK head is a 30" reentry cone for drill-bit, sub-casing, or wireline tool delivery systems. References: Becker, K. and Davis, E.E., 2000, Plugging the Seafloor with CORKs, Oceanus, 42, 14-16. Becker, K., and E.E. Davis, A review of CORK designs and operations during the Ocean

Drilling Program, in Proceedings IODP, edited by A.T. Fisher, Urabe, T., Klaus, A., and the Expedition 301 Scientists, Integrated Ocean Drilling Program Management International, Inc., College Station, TX, 2005.

Davis, E.E., and K. Becker, Using ODP boreholes for studying sub-seafloor hydrogeology: results from the first decade of CORK observations, Geoscience Canada, 28, 171-178, 2001.

Mikada, H., Becker, K., Moore, J.C., Klaus, A. et al., 2002, Deformation and fluid flow processes: Logging while drilling and Advanced CORK in the Nankai Trough accretionary prism, Proc. ODP, Init. Repts, 196, in press.

Mikada, H., Kinoshita, M., Becker, K., Davis, E., Meldrum, R., et al., Hydrological and geothermal studies around Nankai Trough (KR02-10 Nankai Trough Cruise Report), JAMSTEC Journal of Deep Sea Research, 22, 125-171, 2003.

Table 1. ODP Leg 196 ACORK configurations (Modified from Earl Davis’s note) 808I Screen 1 2 3 4 5 6 SeafloorDepth 922 mbsf 879 833 787 533 371 Valve 6 5 4 3 2 1 Sensor 2 3 4 5 6 7 1 Chennel S1 (open) S2 S3 S4 S5 S6 SF Color Black Red Magenta Yellow L.Green Green Blue Hole 1173B Screen 1 2 3 4 5 Seafloor Depth 728 mbsf 569 445 402 359 Valve 1 2 3 4 5 Sensor 6 5 4 3 2 1 Chennel S1 S2 S3 S4 S5 SF Color Black Red Magenta Yellow L.Green Blue Notes: - Screens numbered from bottom up - Sensors are numbered in logging order (as they appear in data files) - 1/8" o.d. geochemistry line used to connect screen 6 to valve 1 and pressure sensor 7 in

Hole 808I - 1/8" o.d. geochemistry line, devoted to separate valved sampling port, connected to

screen 4 in Hole 1173B ‘Channel’ is the header of each column in the *.ACP file. In some cruises the header in *.ACP were numbered on the reverse order but the data itself was ordered in the same way as others. ===== “*.ACP” file contents ==================================== A-Cork 9736 pressures from 11k808i.raw 6407936 12-21-11 04:15:20 logger pressure gauge numbering: 1 2 3 4 5 6 7 line date time Vb SF S1 S2 S3 S4 S5 S6 1 08/10/06 03:20:00 0.00 47674.527 47685.680 47769.148 47701.379 47679.309 47679.000 47680.656 2 08/10/06 03:30:00 0.00 47674.387 47685.707 47769.066 47701.250 47679.199 47678.949 47680.656 3 08/10/06 03:40:00 0.00 47674.258 47685.707 47769.090 47701.379 47679.398 47679.180 47680.949

============================================

Table 2. History of data retrieval 808I --------------------------------------------------------------------------------------------------- Cruise ID Channel order Start time End Time --------------------------------------------------------------------------------------------------- KR02-10 SF S6 S5 S4 S3 S2 S1 2001/06/18 07:20:00 2002/08/02 01:20:00 A 2002/08/02 02:00:00 2002/08/06 00:50:00 B 2002/08/06 01:10:00 2002/08/06 02:05:20 C 2002/08/06 01:10:00 2002/08/06 03:00:00 KR03-05 SF S6 S5 S4 S3 S2 S1 2002/08/06 03:10:00 2003/05/29 03:40:00 YK04-05 SF S6 S5 S4 S3 S2 S1 2003/05/29 04:10:00 2004/04/30 05:20:00 KR06-10 SF S1 S2 S3 S4 S5 S6 2004/04/30 06:00:00 2006/08/24 03:10:00 KR07-18 SF S6 S5 S4 S3 S2 S1 2006/08/24 04:50:00 2007/12/18 03:20:00 KR08-13 SF S1 S2 S3 S4 S5 S6 2007/12/18 04:20:00 2008/10/06 02:40:00 KR11-12 SF S1 S2 S3 S4 S5 S6 2008/10/06 03:20:00 2011/12/21 03:30:00 --------------------------------------------------------------------------------------------------- 1173B --------------------------------------------------------------------------------------------------- Cruise ID Channel order Start time End Time --------------------------------------------------------------------------------------------------- KR02-10 2001/06/01 08:30:00 2002/08/03 04:20:00 KR02-10P 2002/08/03 04:40:00 2002/08/08 01:20:00 KR02-10Q 2002/08/03 04:40:00 2002/08/08 04:10:00 YK04-05 2002/08/08 04:30:00 2004/04/29 05:20:00 KR06-10 SF S5 S4 S3 S2 S1 2004/04/29 05:50:00 2006/08/22 03:10:00 KR07-18 SF S1 S2 S3 S4 S5 2006/08/22 04:37:00 2007/12/19 03:40:00 KR11-12 SF S1 S2 S3 S4 S5 2007/12/19 04:40:00 2011/12/22 02:50:00 ---------------------------------------------------------------------------------------------------

Fig. 1: Schematic diagram of CORK and Advanced CORK borehole observatories. Exchange between permeable subseafloor formations and the ocean is prevented in the CORK by a seal within the inner casing and by multiple packers that isolate individual screens.

Fig. 2 Location of ACORK sensors at Hole 808I left) and 1173B (right) (Sawyer et al., 2008).

2.4. Composite gas-tight fluid sampling system (Miyazaki / Hulme / Kinoshita)

During the KR11-12 cruise, attempts were made to take fluid samples seeping

from the hydraulic port attached to the swellable packer inside the ACORK head. Fluid samples are used for gas and fluid chemistry and microbiology analyses.

Fig. 1 shows the configuration chart of the fluid sampling system used during dive 525 at ACORK 808I. We followed the order 1 through 3.

1: Flow meter Pump speed Low: 1.6ml/sec Medium: 3.2ml/sec High: 4.8ml/sec

drain

2 flow meters

20L Bag

Valve#2

OFF

Pump

D‐WHATS

5‐way valve

Hydraulic r

ACORK

Tank

ACORK connector

US‐type Gas‐tight Sampler*3

MTL temperature

Couple

Couple

2: DWHATS‐US Pump speed Low: 1.6ml/sec Medium: 3.2ml/sec High: 4.8ml/sec

2 flow meters

drain

20L Bag

Valve#2

ON

Pump

D‐WHATS

5‐way valve

Hydraulic r

ACORK

Tank

ACORK connector


Pump speed Low: 1.6ml/sec Medium: 3.2ml/sec High: 4.8ml/sec

3: Bag

2 flow meters

MTL temperature

drain

20L Bag

Valve#2

OFF

Pump

D‐WHATS

5‐way valve

Hydraulic r

ACORK

Tank

ACORK connector


MTL temperature

Hydraulic port at ACORK 808I. (Left) CLOSE position (handle horizontal). (Right) OPEN position (handle upward).

Hydraulic coupler with temperature sensor.

Temperature logger

To 5-way valve

Fluid sampling assembly.

Flow meter with a plastic ball.

D-WHATS Pump

Tank

Flow meter

(Left) 5-way valve. (Right) 2-way valve (#2) to Bag/tank(squeezer).

Tank (left) and a squeezer (right).

Flow(H)

Flow(L)

Sampling

Sample bag (20L).

3. Dive Summary

Dive Date/2011 Site Operations

525 Dec21 808I Data retrieval, Fluid sampling, flow rate, observe

tangled string

526 Dec22 1173B Data retrieval, Fluid sampling

527 Dec23 808I Data retrieval, Fluid sampling, flow rate, observe

tangled string, SSS/SBP

(1) Hole808 I 32_21.215’N, 134_56.700’E, water depth=4,675m

(2) Hole1173B 32_14.683’N, 135_01.484’E, water depth=4,791m

3.1 Dive 525

Dive 525 Photo log

11:38:25 abandoned bridge plug (inflatable packer)

11:41:30 ACORK 808I located.

Closing the valve.

11:59:00 Removing ACORK connector cap white crab is moving

12:00:25 Pullout ACORK connector out of dummy female.

12:02:00- Initial attempt to insert connector fails.

12:29:00 Inspecting tangled strings on the other side of ACORK head

13:48:00 Close-up of aeroquip exit (valve closed)

13:50:40 Insert hydraulic connector

Measurement of flow rate.

13:56:30 Set 5-way Valve to fluid sampling port

13:57:10- Observe US tank, shimmering due to mili-Q fluid venting out from D-Whats

14:06:30- Start squeezing fluid

14:08:00 Squeeze finished OK

14:10:30 Grab the second squeezer

14:12:20- Start squeezing fluid#2

14:13:15 Squeeze#2 finished OK

14:14:50 Turn 2-way valve to Bag

Fluid sampling to 20L-bag.

Observe venting fluid from ACORK hydraulic port

14:52:00 Inspection of tangles strings

Dive 525 Video Log HD1 DVD-1 11:38:25 abandoned bridge plug (inflatable packer) 11:41:30 Arrive ACORK 808I, looking hydraulic outlet. 11:42:10 Observe venting fluid 11:48:00-11:48:30 Observe fluid venting from ACORK hydraulic port (HD2) 11:49:00-11:11:50:00 Close ACORK hydraulic valve (HD2) 11:59:00 Removing ACORK connector cap white crab is moving 12:00:25 Pullout ACORK connector out of dummy female. 12:02:00- Initial attempt to insert connector fails. 12:09:40 Trying to insert again. Fails and keep trying. 12:18:00 Connection successful! 12:29:00 Inspecting tangled strings on the other side of ACORK head HD1 DVD-2 13:31:30 Pull out ACORK connector 13:48:00 Close-up of aeroquip exit (valve closed) 13:50:40 Insert hydraulic connector 13:56:00 Measure flow rate with ball flowmeter (HD2) 13:56:30 Set 5-way Valve to fluid sampling port 13:57:10- Observe US tank, shimmering due to mili-Q fluid venting out from D-Whats 14:06:30- Start squeezing fluid 14:08:00 Squeeze finished OK 14:10:30 Grab the second squeezer 14:12:20- Start squeezing fluid#2 14:13:15 Squeeze#2 finished OK 14:14:50 Turn 2-way valve to Bag 14:52:00 Inspection of tangles strings Dive 526 HD1 1/2 10:11:00 Observe Marker 266-1 near ACORK 1173 This marker was deployed during KR02-10 cruise during the heat flow measurement. 10:18:00 Locate ACORK

10:31:30- Approaching ACORK 10:33:00 Grab ACORK on the right-hand manipulator 10:37:10 Grab UMC 10:38:30- Trying insert UMC to ACORL port 10:43:55 Drop UMC 10:44:33 View of ROV platform (need for future deployment of PPC) 10:45:10 Try picking up UMC (grab cable) 10:55:00 UMC picked up, no damage, no mud inside 11:02:20 Put UMC back to dummy plug on the basket 11:13 Grab ACORK with right hand 11:16:50 Grab ACORK with left hand 11:19:10 Take out UMC from dummy 11:23:30 Insert UMC to ACORK female, incomplete 11:27 Right arm comes off of UMC 11:30 Grab by right, detach left and grab again. Unstable situation. 11:33 Trying to move the cable for complete insertion 11:39:40 Complete, start downloading

3.2 Dive 526

526 Photo log

10:11:00 Observe Marker 266-1 near ACORK 1173

This marker was deployed during KR02-10 cruise during the heat flow measurement.

10:18:00 Locate ACORK

10:31:30- Approaching ACORK

10:33:00 Grab ACORK on the right-hand manipulator

10:37:10 Grab UMC

10:38:30- Trying insert UMC to ACORK port

10:43:55 Drop UMC

10:44:33 View of ROV platform (need for future deployment of PPC)

10:45:10 Try picking up UMC (grab cable)

10:55:00 UMC picked up, no damage, no mud inside

11:02:20 Put UMC back to dummy plug on the basket

11:13 Grab ACORK with right hand

11:16:50 Grab ACORK with left hand

11:19:10 Take out UMC from dummy

11:23:30 Insert UMC to ACORK female, incomplete

11:27 Right arm comes off of UMC

11:30 Grab by right, detach left and grab again. Unstable situation.

11:33 Trying to move the cable for complete insertion

11:39:40 Complete, start downloading

3.3 Dive 527

Dive 527 video log

11:13 Connecting UMC to ACORK: This does not work (cable will stack)

You need to rotate like this, and….

This will work!

11:45 Data download completed.

11:48 Cap was set for next year’s revisit.

11:51 Before vent open

12:06 Flow measurement with metal ball

Turn 5-way valve to ‘fluid sampling’.

12:09 Venting mili-Q

12:16 Turning the valve to Bag mode.

12:31 Bag sampling is begin made.

21:51 Measure flow rate again. The same as before measured at 12:06.

Fluid is still venting.

13:02 Inspecting the valve side of ACORK.

13:27 Inspecting 10” casing.

4. Preliminary data and post-cruise research plan

4.1. Summary of ACORK results During the KR11-12 cruise, we successfully retrieved a 3 year and 2 months-long data from ACORK 808I site, and a 4-year-long new data from 1173B. We now have 11.5-year-long continuous pressure records since June 2001 at both sites. Fig. 4.1 shows the pressure data at ODP Holes 808I and 1173B. Most of pressure data from multiple depths show constant values with tidal signals throughout the period. Transient changes were only observed at the time of nearby earthquakes. During the recent 3 to 4 years, a spiky anomaly was detected at the time of Mar. 11 Tohoku earthquake.

Fig. 4.1 Pressure data at ODP Holes 808I and 1173B.

4-2. Pore fluid geochemistry

Fluid samples were collected on all three of the dives. On the first dive (KK525), a

prototype syringe sampler (referred to as a “Squeezer”) was used to collect borehole fluids being

pumping into a 0.5 L accumulator tank covered with a rubber flap to prevent mixing with ambient

seawater. The primary sampling system was driven off of a peristaltic pump that flowed at 250

mL/min through a series of 3 60 mL titanium cylinders to a 2-way valve. After flushing the sterile

milliQ water from the system, the valve was switched to a hose connected to a sterile 20L bag. Due

to the limited time of the dives, the bag was only partially filled, and the gas-tight cylinders were

closed and the pump shut off. This system was very effective at capturing borehole fluids, and so the

Squeezer samplers were not deployed on subsequent dives to save time for other activities and

obtain a larger volume bag sample. This pumping system was used during dive KK526 while near

the bottom to collect a background sample of near-bottom seawater.

The samples were taken immediately from Kaiko to the laboratory for processing. A split

was taken from the bag sampler for inorganic geochemistry, along with one of the 60 mL titanium

gas-tight samples and the Sqeezers. The inorganic geochemistry samples were filtered with a 0.45

micron filter into acid-washed HDPE bottles, with a small unfiltered amount saved for particulate

analysis. Splits of the filtered samples were treated with 1 N HCl to prevent the formation of silicon

dimers that can occur in the anticipated high-silica fluids. For each sample a 4 mL HDPE bottle was

filled to overflowing and capped tightly for future stable isotope analysis of the water. A 3 mL split

was analyzed on the ship for pH and alkalinity and the residue was saved for future analysis.

The remaining sampled fluids will be analyzed for a wide range of chemical species and

using a variety of methods. The major and minor ions in seawater via ICP-AES, chlorinity by

titration, sulfate and bromide by ion chromatograph, ammonium by colorimetric determinations,

fluoride by ion selective electrode, and the trace and rare earth elements with an ICP-MS. We also

can get the samples analyzed for stable isotopes (H, O, Sr, S, C, Li and B) depending on the need

and concentration observed from the elemental analyses. The purpose of these studies will be

primarily to determine the source of the fluid production. Many of the large ion lithophile elements

are useful thermal indicators of mineral-fluid interactions. Additionally, the rare earth element

patterns can be used to determine the lithology of the host rock that the fluid was initially in

equilibrium with. Stable isotopes of the water molecules also make great thermal indicators and will

likely be analyzed shortly after the cruise.

Table of fluid samples taken on the expedition.

Dive

KK525:

ACORK

808I

Sample

Name Description Preparation

volume

(mL) analyses planned

KK525

Big S F

Filtered 0.45 um into acid‐washed

HDPE bottles. 65

Major and minor elements

(ICP‐AES), trace elements

(ICP‐MS), nutrients (colorimetry)

KK525

Big S UF

placed directly in to acid‐washed

HDPE bottles 30

dissolution of particulates for

metal analysis

KK525

Big S

1:10 HCl


HDPE bottles and added 200 uL of 1N

HCl. 2

trace metals for possible

absorption effects of delayed

acidification

KK525

Big S 4:1

HCl


HDPE bottles and added 3 mL of 1N

HCl. 0.75 Dissolved Si (ICP‐AES)

KK525

Big S OH


HDPE bottles with no head space. 4

Oxygen and Hydrogen isotopes of

water

KK525

Big S Alk


HDPE bottles and titrated with HCl for

alkalinity. 3 backup for minor element analysis

KK525

Big S

A&B

Transferred directly to sterile

cryotubes and stored in ‐80 freezer 2 x 1

Microbial community structure

through DNA and RNA analyses

(ion torrent sequencer)

KK525

Big S

C&D


cryotubes and preserved with 100 uL

of glycerol TE buffer and stored in ‐80

freezer 2 x 1




KK525

Big S

E&F



of LifeGuard buffer and stored in ‐80

freezer 2 x 1




KK 525

Big S

MBIO

ACORK 808I fluids

sampled with 150

mL squeezer inside

outflow

accumulator

Transferred directly to 50 mL sterile

centrifuge tube and stored in ‐80

freezer 30




KK525

50 mL S

F


HDPE bottles. 8




KK525

50 mL S

UF


HDPE bottles 4


metal analysis

KK525

50 mL S

1:10 HCl



HCl. 2



acidification

KK525

50 mL S

4:1 HCl




KK525

50 mL S

OH




water

KK525

50 mL S

Alk




KK525

50 mL S

A&B






KK525

50 mL S

C&D




freezer 2 x 1




KK525

50 mL S

E&F




freezer 2 x 1




KK 525

50 mL S

MBIO

ACORK 808I fluids

sampled with 50 mL

squeezer inside

outflow

accumulator



freezer 18




KK525

Bag F


HDPE bottles. 20




KK525

Bag 1:10

HCl



HCl. 2



acidification

KK525

Bag 4:1

HCl




KK525

Bag OH




water

KK525

Bag Alk




KK525

Bag A&B






KK525

Bag C&D




freezer 2 x 1




KK525

Bag E&F




freezer 2 x 1




KK 525

Bag

MBIO

ACORK 808I fluids

sampled with a 20 L

sterile bag while

pumping



freezer 42




KK525 Ti

F


HDPE bottles. 16




KK525 Ti

UF

ACORK 808I fluids

sampled with 60 mL

titanium gas‐tight

cylinder while

pumping


HDPE bottles 4


metal analysis

KK525 Ti

1:10 HCl



HCl. 2



acidification

KK525 Ti

4:1 HCl




KK525 Ti

OH




water

KK525 Ti

Alk




KK525 Ti

A&B






KK525 Ti

C&D




freezer 2 x 1




KK525 Ti

E&F




freezer 2 x 1




KK 525

Ti MBIO



freezer 10




Dive

KK526:

ACORK

1173B

Sample


volume


KK526 Ti

BW F

Background bottom

seawater sampled


HDPE bottles.

25 Major and minor elements



KK526 Ti

BW UF


HDPE bottles 15


metal analysis

KK526 Ti

BW OH




water

KK526 Ti

BW A&B






KK526 Ti

BW C&D




freezer 2 x 1




KK526 Ti

BW E&F




freezer 2 x 1




KK 525

Big S

MBIO

with titanium

gas‐tight system

while pumping



freezer 9




KK526

Bag BW

F

Background bottom

seawater sampled

with bag system


HDPE bottles. 25




Dive

KK527:

ACORK

808I

Sample


volume


KK527

Bag F

ACORK 808I fluids

sampled with a 20 L

sterile bag while


HDPE bottles. 60




KK527

Bag UF


HDPE bottles 8




KK527

Bag 1:10

HCl



HCl. 2



acidification

KK527

Bag 4:1

HCl




KK527

Bag OH




water

KK527

Bag Alk




KK527

Bag A&B






KK527

Bag C&D




freezer 2 x 1




KK527

Bag E&F




freezer 2 x 1




KK 525

Bag

MBIO

pumping



freezer 42




KK527 Ti

F


HDPE bottles. 25




KK527 Ti

UF

ACORK 808I fluids

sampled with 60 mL

titanium gas‐tight

cylinder while

pumping


HDPE bottles 4


metal analysis

KK527 Ti

1:10 HCl



HCl. 2



acidification

KK527 Ti

4:1 HCl




KK527 Ti

OH




water

KK527 Ti

Alk




KK527 Ti

A&B






KK527 Ti

C&D




freezer 2 x 1




KK527 Ti

E&F




freezer 2 x 1




KK 525

Ti MBIO



freezer 10




Temperature data

Temperature data was logged during the fluid sampling using a stand-alone miniature

temperature logger (see explanatory note). Fig. 4-2 shows the plot of temperature during dives 525

and 527. Dive 525 Temperature log. Temperature during the fluid sampling is 1.600 degC, whereas it is 1.598 degC when disconnected. Dive 527 temperature log. As in dive 525, temperature during connections is ~3mK higher than disconnected status.

Fig. 4-2(a) Dive 525 Temperature log. Temperature during the fluid sampling is 1.600 degC, whereas it is 1.598 degC when disconnected.

Fig. 4-2(b) Dive 527 temperature log. As in dive 525, temperature during connections is ~3mK higher than disconnected status.

4-3. Microbiology

Sub-samples were taken for microbial analysis from the Squeezers, the 20 L bag, and the

60 mL geochemistry gas-tight cylinder. These samples were all preserved in sterile centrifuge tubes

and cryotubes immediately upon vehicle recovery. The samples were preserved by 3 methods: 1)

simple freezing at -80 degrees; 2) addition of 100 uL of glycerol TE buffer to 1 mL of sample and

freezing at -80; and 3) addition of 800 uL of LifeGuard buffer to 1 mL of sample and freezing at -80.

These samples will be shipped frozen to the Center for Dark Energy Biosphere Investigations

(C-DEBI) at the University of Southern California to be analyzed by Drs. Katrina Edwards and Beth

Orcutt. They can conduct molecular biological analyses on the water samples collected. This is

accomplished by extracting DNA and performing polymerase chain reaction for the V3 region of the

16S rDNA, and then sequence using the ion torrent sequencer. Depending on these results, they

could conduct metagenomic analyses using 454 sequencing. Data will be deposited in genbank. All

of the data would be publishable in a high quality journal (i.e., Earth and Planetary Sci. Lett

(chemistry) and The ISME Journal (microbiology).

Shore-based study

Detecting methanogens by culture dependent and independent analyses

Junichi Miyazaki

Subsurface Geobiology Advanced Research (SUGAR) Project, JAMSTEC The previous analysis showed that deep crustal fluid sprung out from CORK 808I included high amount of methane. And also the results demonstrated that the carbon isotope ratio of methane was very light, suggesting the methane was biologically produced. It is known that methanogenesis by microbes was performed only by methane producing archaea called methanogen. Methanogens obtain energy and carbon source by reduction of carbon dioxide, methanol, methyl amines, or acetate. In the course of reduction, methane was produced as a by-product. These methanogens were thought as an important key player in subsurface microbial ecosystems. The purpose of the shore-based study utilizing samples in this KR11-12 cruise are to detect methanogens by culture dependent and independent analyses. The D-WHATS samples will be used for cultivation of methanogens and direct counting of microbes and methanogens. And also we extracted DNA from the samples filtrated from bag fluid samples. The extracted DNA was used for detecting methanogens by their functional gene marker, mcrA gene which is a key enzyme of methanogenesis. And also we will estimate the quantity of methanogens by quantitative PCR analysis of mcrA gene. Tomohiro Toki (University of the Ryukyus) will analyze the concentration of gases (hydrogen, methane, helium and so on and carbon isotopic ratio of methane and carbon dioxide.

4-4. Flow meter measurements of ACORK venting

A novel attempt was made to measure the rate of fluid flowing out of the ACORK at Site

808I using a combination of mechanical ball flow meters of different scales. The flow meters were

connected to a 4-way valve that went to the umbilical attached to the ACORK so that each flow

meter could be tested individually and then the flow could be directed to the pumping system for

sampling.

Apparatus used to calibrate the flow meters.

4-5. Sub-bottom profiling and side-scan-sonar record (Kinoshita)

ub-bottom profiling and side-scan-sonar survey was carried out during dive 527 using

KAIKO launcher. Starting from Hole 808I, survey was made across the second frontal thrust in the

azimuth of 315 deg.

Track of KAIKO launcher during SSS/SBP survey.

On a Christmas Eve

kr11-12 cruise in the nankai trough off muroto€¦ · we also confirmed that closing the valve at...

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