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Science objectives and drilling plan:

The goal of Expedition 331 is to directly sample hydrothermally active mounds in the Okinawa Trough to obtain evidence for microbial communities. This includes variations in biomass and species diversity, as well as the function and impact of such active subseafloor microbial ecosystems underneath the hydrothermal vents. The results are expected, not only to provide clues to the role of a subsurface biosphere left untouched deep under the sea, but also to help understand the mechanism of microbial methane generation and gas transport in seafloor sediments. The expedition also expects to reveal the relationship between the extent of subseafloor microbial communities and methane commonly found at high concentration in the hydrothermal fluids, and the formation of hydrothermal mineral deposits.

Coring up to 50 meters below seafloor (mbsf) is planned for sites on the hydrothermal mounds or in adjacent areas. Following the coring, steel casing pipes will be installed within the boreholes for future installation of an in-situ incubator.

On the margin of the hydrothermal vent field, hydrothermal fluids mix into sea water in subseafloor sediment, creating a unique and extremely active microbial environment (a subsurface analogue to surface estuary). Target drilling depths in this area are 100 mbsf and 200 mbsf. Coring and casing pipe installation are also planned.

Expected outline of operations during the period onboard

8 August - 29 August, 2010 Preparation for the expedition at Shimizu port

29 August - 31 August

Transit from Shimizu Port to Shingu Port
Mid-August Helicopter underwater escape and sea survival training for science party
1 September - 5 September Material loading and embarkation of science party (at Shingu Port)
5 September Sailing out from Shingu Port
9 September - Arrive at the drill sites at the Okinawa Trough and drilling operation start
18 September Port call at Nago, Okinawa
Disembarkation of filming/interviewing crew
3 October 2010 Completion of Expedition 331

*The above schedule is liable to change depending on weather and other operational requirements.

Expected outline of operations during the period onboard

  • Transit to the drill sites
  • Installation of transponders onto the seafloor using a remotely operated vehicle (ROV)
  • Operation of Dynamic Positioning System in the survey area
  • Assemblage and lowering of drilling unit/equipment
  • Final selection of the drill sites and commencement of drilling
  • Coring and subsequent shipboard research activities
  • Installation of casing pipes

* The above operations are subjected to change due to weather and other operational requirements.

Co-Chief Scientists

Ken Takai, Program Director, Institute of Biogeosciences (Biogeos), JAMSTEC
Another Co-Chief Scientist: TBA

Ken Takai

An international team of scientists, composed of about 20 people from IODP member countries, will join the expedition.