CHARMNZ 2006

R/V TANGAROA TAN-0607, 20 June – 2 July 2006

CHARMNZ (CH4 Hydrates on the AccRetionary Margins of New Zealand), R/V Tangaroa’s voyage TAN0607, was the first ever research cruise dedicated to studying gas hydrates offshore of New Zealand. CHARMNZ was a cooperative research programme in the offshore Wairarapa – Hawke’s Bay region (Pecher et al. 2007; Coffin et al. 2008).

Summary

During the 13-day voyage, we successfully acquired a comprehensive dataset from gas hydrate deposits on the Hikurangi margin mainly in two study areas, the Porangahau Ridge and Rock Garden. We acquired high-resolution seismic data, mapping an amplitude anomaly beneath Porangahau Ridge. Pore water chemistry and heatflow data from this ridge indicate the presence of a fluid flow anomaly. Seismic data from Rock Garden display evidence for numerous gas pockets close to the seafloor. We collected dredge samples of the hard sediments on Rock Garden. Water above several vent sites was probed on Rock Garden with Niskin bottles attached to CTDs. We retrieved paleoceanographic cores that should allow us to reconstruct water temperatures on the timescale of thousands of years and a temperature sensor record of water temperatures close to Rock Garden over 15 months. TAN0607 was the first-ever research campaign aimed at studying gas hydrates on the Hikurangi margin. It was also the first of three major research campaigns targeting gas hydrates on the Hikurangi margin within a year. We anticipate that interpretation and publication of results from all three cruises will vastly expand our knowledge of the Hikurangi margin gas hydrate system and more generally, of fluid and gas expulsion from this subduction zone.

Collaborators

  • GNS Science
  • U.S. Naval Research Laboratory (NRL)
  • National Institute of Water and Atmospheric Research (NIWA)
  • University of Otago
  • University of Hawaii
  • University of Rochester, New York
  • University of Auckland
  • GeoForschungsZentrum Potsdam

Scientific Objectives

  • To study the nature and extent of a seismic amplitude anomaly within the gas hydrates stability zone beneath the Porangahau Ridge, in particular, whether it is caused by free gas and/or highly concentrated gas hydrates (Crutchley et al. 2006)
  • To improve our understanding of potentially hydrate-related seafloor erosion of Rock Garden and Ritchie Banks (Pecher et al. 2005)
  • To search for evidence of venting on Rock Garden and its relation to gas hydrates (Lewis & Marshall 1996; Faure et al. 2006)

Survey Operations

  • Multibeam bathymetry
  • 3.5 kHz echosounder
  • Short-streamer multichannel seismic
  • Piston coring for pore-water chemistry, isotopes, and microbiology
  • Piston coring for paeloceanographic analyses
  • Seafloor thermometry
  • Dredges for seafloor sampling and carbonate analyses
  • Water column acoustic (echosounder)
  • Water column chemistry (Niskin bottles)

Cruise Participants

Pecher Dr. Ingo GNS Voyage leader, seismic, multibeam, 3.5 kHz
Coffin Dr. Richard NRL Voyage co-leader, piston core/heat flow
Henrys Dr. Stuart GNS Voyage co-leader, seismic, multibeam, 3.5 kHz
Faure Dr. Kevin GNS Water column chemistry
Greinert Dr. Jens GNS &
U. of Ghent, Belgium
GNS coordinator piston cores, water column chemistry, flare imaging, carbonates, pore water chemistry, multibeam processing
Orpin Dr. Alan NIWA Paleoceanographic coring, multibeam, 3.5 kHz
Gerring Pete NIWA Engineer/technician
McGill Kevin NIWA Engineer/technician
Mitchell John NIWA Engineer/technician
Wilcox Steve NIWA Engineer/technician
Gorman Dr. Andrew U. of Otago Seismic, student advisor
Crutchley Gareth U. of Otago Student watchstander
Fohrmann Miko U. of Otago Student watchstander
Kilner Jeremy U. of Otago Student watchstander
Senger Kim U. of Otago Student watchstander
Wood Dr. Warren NRL Piston core/heatflow
Hamdan Dr. Leila NRL Piston core/microbiology
Pohlman Dr. John NRL Piston core
Smith Joe U. of Mass (NRL) Piston core
Dale Celeste NRL Piston core
MacDonald Bob Biologica Ltd (NRL) Heatflow/piston core
Downer Ross Milbar Hydro-Test (NRL) Piston core/heatflow, engineer
Bryant Layton Milbar Hydro-Test (NRL) Piston core/heatflow, engineer
Kurasaki Dr. Ryan U. of Hawaii Microbiology
Yoza Dr. Brandon U. of Hawaii Microbiology
Tomaru Dr. Hitoshi U. of Rochester Iodine isotopes, halogens, oxygen, hydrogen
Kukowski Dr. Nina GFZ Potsdam, Germany Tectonics, multibeam
Schinteie Richard U. of Auckland Student watchstander, pore water analysis, carbonates

Download: TAN0607 Cruise Report (23 MB).
Results from expeditions R/V Sonne SO-191 (NewVents) and R/V Tangaroa TAN0607 (CHARMNZ) will be published in a special issue of Marine Geology.

Acknowledgments

Cruise and cruise participants were funded by various New Zealand, US and European agencies.

New Zealand

Projects at GNS Science:

  • National Petroleum Resources, Offshore Frontiers, Gas Hydrates (Foundation for Research, Science, and Technology, FRST, Energy Portfolio), contract C05X0302 to GNS Science
  • “How do gas hydrates weaken the seafloor, causing submarine slides and tsunamis?” (Royal Society of New Zealand Marsden Fund), GNS Science in collaboration with NIWA and the U. of Otago)
  • “Gas hydrates” Capability Fund, GNS Science

We also acknowledge significant NIWA Capability Funds.

U.S.A.

  • “Quantify the processes responsible for the distribution of gas hydrate (meters to hundreds of meters scale) associated with representative seafloor seeps” NRL research focus on an Advanced Research Initiative (ARI)
  • Office of Naval Research sponsored program for the Marine Biogeochemistry Section, Naval Research Laboratory and Hawaii Natural Energy Institute, University of Hawaii for International Collaboration on Methane Hydrate Research and Development
  • Department of Energy, National Energy Technology Laboratory National Methane Hydrate R & D.

Europe

Laboratory equipment and chemicals for Jens Greinert to conduct pore water analyses and water column methane measurements were funded via a EU Marie Curie Grant (MOIF-CT- 2005-007436).

We greatly appreciate the enthusiasm, skills, and piloting of Captain Baker and his crew on board the R/V Tangaroa, which was crucial for tackling the many challenges during this cruise and for making this cruise successful. We would also like to acknowledge NIWA Vessels for their handling of this logistically complex cruise. We are particularly grateful to NIWA Vessels for accommodating our voyage at its original time slot despite a mechanical problem that required re-scheduling of a number of surveys. Thanks also go to IfM-Geomar, Kiel, Germany, who helped with ICP-OES measurements.

References

  • Coffin R, Hamdan L, Pohlman J, Wood W, Pecher I, Henrys S, Greinert J, Faure K, Gorman A, Orpin A 2008. Geochemical Characterization of Concentrated Gas Hydrate Deposits of the Hikurangi margin, New Zealand NRL-6110-2007.
  • Crutchley GJ, Pecher IA, Henrys SA, Gorman AR 2006. Gas hydrate "sweet spots" on the Hikurangi margin, from recently acquired multi-channel seismic data. Proc. New Zealand Petrol. Conf. Auckland. Pp. 7pp.
  • Faure K, Greinert J, Pecher IA, Graham IJ, Massoth GJ, de Ronde CEJ, Wright IC, Baker ET, Olson EJ 2006. Methane seepage and its relation to slumping and gas hydrate at the Hikurangi margin, New Zealand. N. Z. J. Geol. Geophys. 49: 503-516.
  • Lewis KB, Marshall BA 1996. Seep faunas and other indicators of methane-rich dewatering on New Zealand convergent margins. N. Z. J. Geol. Geophys. 39: 181-200.
  • Pecher IA, Coffin R, Henrys SA, CHARMNZ Working Group 2007. Cruise Report: gas hydrate exploration on the East Coast, North Island, New Zealand. GNS Science Report 2007/29. 112 p.
  • Pecher IA, Henrys SA, Ellis S, Chiswell SM, Kukowski N 2005. Erosion of the seafloor at the top of the gas hydrate stability zone on the Hikurangi Margin, New Zealand. Geophys. Res. Lett. 32: L24603.