Geochemical Characterization of Concentrated Gas Hydrate Deposits on the Hikurangi Margin, New Zealand: Preliminary Geochemical Cruise Report

• Main Authors: Coffin, Richard B., Hamdan, LeiLa, Pohlman, John, Wood, Warren, Pecher, Ingo, Henrys, Stuart, Greinert, Jens, Faure, Kevin, Gorman, Andrew, Orpin, Alan
• Other Authors: NAVAL RESEARCH LAB WASHINGTON DC CHEMISTRY DIV
• Format: Text
• Language: English
• Published: 2008
• Subjects: Biological Oceanography; Geology; Geochemistry and Mineralogy; Mining Engineering; *GEOCHEMISTRY; *GEOPHYSICAL PROSPECTING; *METHANES; SEISMIC DETECTION; CONTINENTAL SHELVES; MARINE BIOLOGY; NEW ZEALAND; HEAT TRANSMISSION; MICROBIOLOGY; LITTORAL ZONES; SEDIMENTS; *GEOCHEMICAL POREWATER PROFILES; SEISMIC PROFILES; GAS HYDRATES; HIKURANGI MARGIN; DEEP SEDIMENT HYDRATES DEPOSITS; OCEAN CARBON; MARINE SEDIMENTS; CLIMATE CHANGE; MICROBIAL ANAEROBIC OXIDATION; SEISMIC EXPLORATION; Canada; New Zealand; Methane hydrate
• Online Access: http://www.dtic.mil/docs/citations/ADA478461; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA478461

This report provides a preliminary summary of geochemical contribution to methane hydrate research and exploration on the Hikurangi Margin, off the northeastern coast of New Zealand from June 20 to July 3, 2006. Geochemical porewater profiles taken from shallow piston cores and vertical fluid migration measured with heatflow probing were compared with seismic summaries of potential deep sediment hydrates deposits. Research goals for this expedition include: (1) Refine geophysical, geochemical, and microbiological technologies for prospecting hydrate distribution and content; (2) Contribute to establishing high-priority geographical regions of prospective interest, in terms of methane volume estimates; (3) Prediction of environmental effects and geologic risks at the continental margin associated to the natural resource occurrence and resource exploitation; and (4) Expand understanding of the biogeochemical parameters and associated microbial community diversity in shallow sediments that influences the porewater sulfate gradient observed through anaerobic methane oxidation profiles. Scientists from New Zealand, United States, Belgium, Canada and Germany, representing 11 university and government research institutions contributed to this expedition. Expertise of the science team resulted in the contribution of geochemical, geophysical, geological, molecular ecology, and biological data to address ocean water column, sediment, and porewater research questions. Prepared in collaboration with Geological and Nuclear Sciences, Lower Hutt, NZ; Department of Geology, University of Otago, Dunedin, NZ; and National Institute of Water and Atmospheric Research, Kilbirnie, Wellington, NZ. The original document contains color images.