cruise report nt13-22 r/v natsushima & rov hyper dolphin ... data logger and a lithium battery...

Download Cruise Report NT13-22 R/V Natsushima & ROV Hyper Dolphin ... data logger and a lithium battery pack,

Post on 03-Aug-2020

0 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Cruise Report

    NT13-22

    R/V Natsushima & ROV Hyper Dolphin

    Iheya North Ridge, Okinawa Through

    2013

  • Contents

    1. Cruise Information

    1.1. Cruse number

    1.2. Name of vessel and submersible vehicle

    1.3. Title of the cruise

    1.4. Titles of the proposal

    1.5. Cruise period

    1.6. Ports of call

    1.7. Research area

    2. Research map

    3. Research team

    4. Observation/ Investigation

    5. Preliminary Research results

    6. Acknowledgment

    7. Appendix

    Payload plan

    Specification and Crew of R/V Natsushima and ROV Hyper Dolphin

    2

  • 1. Cruise Information

    1.1. Cruise number

    NT13-22

    1.2. Name of vessel and submersible vehicle

    R/V Natsushima and ROV Hyper Dolphin

    1.3. Title of the cruise

    Biological monitoring and physical exploration researches

    1.4. Title of the proposals

    1) Monitoring the hydrothermal ecosystem and assessment of effects of drilling activity

    2) DC resistivity survey and OBEM operation

    3) Feasibility study for mineral harvesting system from hydrothermal fluid

    1.5. Cruise period

    7 to 19 November y 2013

    1.6. Ports of call

    Departure: Yokosuka

    Arrival: Naha

    3

  • 1.7. Research area

    Iheya North Ridge, Okinawa Trough

    27° 46.5’N 126° 53.0’E to 27°49.0’N 126°55.3’E

    Water depth: 850-1500m

    4

  • 2. Research map

    Location of research area in Okinawa Trough

    Surveillance points in hydrothermal field of Iheya North Knoll

    C0013 : 27°47.42’N, 126°53.85’E, 1035m, C0014: 27°47.43’N, 126°54.05’E, 1059m,

    C0016: 27°47.45’N, 126°53.80’E, 998m, C0017: 27°47.50’N, 126°54.72’E, 1129m

    5

  • 6

  • 3. Research team (onboard)

    Chief Investigator:

    Hiroyuki Yamamoto (JAMSTEC)

    Onboard Researchers:

    Video survey:

    Tetsuya Miwa

    Ryota Nakajima

    (JAMSTEC)

    (JAMSTEC)

    Biological survey:

    Masako Nakamura

    Takuya Yahagi

    Seinosuke Teruya

    Frederic Sinniger

    (OIST)

    (Tokyo Univ)

    (Tokyo Univ)

    (JAMSTEC)

    Environmental survey:

    Junichi Miyazaki

    Katsunori Yanagawa

    Yuka Masaki

    Hideaki Machiyama

    (JAMSTEC)

    (JAMSTEC)

    (JAMSTEC)

    (JAMSTEC)

    Physical survey:

    Tada-nori Goto

    Takafumi Kasaya

    (Kyoto Univ)

    (JAMSTEC)

    Engineering study:

    Masayuki Watanabe (JAMSTEC)

    Technical supporting stuff:

    Hisanori Iwamoto (NME)

    7

  • 4. Observation / Investigation

    4.1 Overview This research cruise has been planned for three subject; 1) annual survey the

    post-drilling environments of IODP Expedition 331 on hydrothermal field in Iheya

    North Knoll, 2) DC resistivity survey and OBEM operation, and 3) feasibility study for

    mineral harvesting system from hydrothermal fluid.

    4.2. Habitat mapping Habitat mapping is a basic approach to understand a situation of community and a

    linkage between habitat condition and distribution pattern of organisms. The data on

    seafloor bathymetry, seabed classification, benthic faunae have been collected in this

    deep-sea expedition. The video survey of seafloor using downward-facing video

    camera was conducted to analyze the animal distribution.

    4.3. Survey of biological diversity and distribution pattern Hydrothermal system sustains dense and diverse communities in deep-sea ecosystem. In

    this cruise two approaches by taxon-based and gene-based have been conducted.

    Benthos aggregation and sediment were collected for this study.

    4.4 In-situ experiment on benthic community Understanding the process of migration and settlement of benthic community including

    microorganisms and megabenthos is a crucial issue in study of deep-sea ecosystem. In

    this cruise, we conducted in-situ experiment for larvae settlement of benthos, and in-situ

    cultivation system for prokaryotes. The long-term measurement of seawater movement

    in bottom layer was conducted to analyze the migration pathway of planktonic larvae.

    4.5. Environmental survey using physical and chemical sensors Physical and chemical properties in surrounding area of hydrothermal system are data to

    determine the extent of chemosynthesis-based ecosystem. In this cruise, several types of

    physicochemical sensors were examined.

    8

  • 4.6. DC resistivity survey and OBEM operation

    4.6.1 DC resistivity survey The recent growth of world-wide requirement of metals demands advanced explorations

    for finding metal mine and deposits. Especially, the submarine massive sulphides

    (SMS) have attracted mining companies because of its compactness with high grades.

    However, few exploration techniques were developed to evaluate the thickness of SMS

    and to find the buried SMS.

    One of the great problems is the rough seafloor feature near the hydrothermal area,

    which restricts the ways for marine controlled-source electromagnetic (CSEM) survey.

    Recently, the deep-towed CSEM technique is used for imaging the shallower structure

    below the seafloor for detection of methane hydrate etc. (e.g., Schwalenberg et al.,

    2005). However, the deep- towed CSEM survey requires a long towed cable for

    source and receiver electrodes. The rough topography does not allow the towing just

    on the seafloor. The high altitude of towed cable gives us a chance of towing but the

    obtained data mainly reflect the seawater layer below the cable, so that the resolution to

    the sub-seafloor structure is decreased.

    Here, we propose a new EM exploration technique with a Remotely Operated Vehicle

    (ROV) as shown in Fig. 4.6.1.1. In

    our concept, the ROV-based DC

    resistivity survey system consists of

    two instruments; i) on-line

    transmitter and receivers attached to

    ROV and ii) off-line receiver. The

    former can measure the seafloor

    resistivity with sounding depth of

    1-2m due to the short

    source-receiver separation. The

    later receiver (ocean-bottom

    electrometer=OBE) can be

    simultaneously used for keeping far

    source-receiver distances to obtain

    the deeper images (with depth of Fig. 4.6.1.1. Schematic drawing of

    ROV-based marine DC resistivity survey.

    9

  • 2-30m). In this cruise, we test our newly developed system to image the sub-seafloor

    resistivity structure below the SMS deposits in the Iheya north hydrothermal area.

    The detailed introduction of our DC resistivity survey system is summarized below

    (Figs. 4.6.1.2-4.6.1.3). In this study, we use only one OBE for the far receiver.

    Fig. 4.6.1.2 Schematic drawings of ROV-based marine DC resistivity survey. The source

    amplitude was 1-10 amperes in this study. The dipole length of source (TX) and receiver (RX)

    were about 2m and 1m, respectively. The dipole length of OBE was about 1m.

    Fig. 4.6.1.3. Payload of Hyper-Dolphin Dive #1594.

    The payload setting was same at Dive s#1595 and #1596

    10

  • Fig. 4.6.1.4. Ocean Bottom Electrometer (OBE). Receiver electrodes are installed

    in the four pipes (with dipole length of about 1m).

    4.6.2 OBEM The OBEM system can measure time variations of three components of magnetic field,

    horizontal electric field, the instrumental tilts, and temperature. In this cruise, we carried

    out the deployment and recovery test operation of new type system. It mainly consists

    of one 17-inch glass sphere float, two aluminum pressure cases and electrode arm unit

    with arm holding mechanism (Fig. 4.6.2.1). The main aluminum case involves main

    11

  • data logger and a lithium battery pack, and a fluxgate sensor is installed in a smaller

    case. The electrodes are Ag-AgCl equilibrium type made by Clover Tech. For electric

    field, four voltage differences between the electrodes on the tip of the pipes and the

    ground electrode are measured. A transponder unit, radio beacon and a flash light are

    also mounted on this system. The acoustic system can communicate with the SSBL

    system and it is easy for us to detect its position in the sea or on the seafloor. This

    system is based the existing OBEM system with the arm holding system developed by

    JAMSTEC (Kasaya and Goto, 2009). This arm holding mechanism (Japan patent No.

    4346605), which electrode arm is folded when OBEM is in surfacing (Fig. 4.6.2.2),

    enable recovery operation.

    Fig. 4.6.2.1 New OBEM system

    12

  • Fig. 4.6.2.2 Electrode arm-holding mechanism of an OBEM

    4.5. Mineral harvesting system Hydrothermal fluid contains many minerals and metals, which are characterized by

    ingredients of

View more >