'Frozen' Natural Gas Discovered At Unexpectedly Shallow Depths Below Seafloor

Contrary to established expectations of how gas hydrate deposits form, IODP expedition co-chief Michael Riedel, of McGill University, Montreal, confirms, “We found anomalous occurrences of high concentrations of gas hydrate at relatively shallow depths, 50-120 meters below the seafloor.”

The science party used the drilling facility and laboratories of the U.S. research vessel, JOIDES Resolution, on a 43-day expedition in Fall 2005 during which they retrieved core samples from a geological area known as the (northern) Cascadia Margin. Gas hydrate deposits are typically found below the seafloor in offshore locations where water depths exceed 500 meters, and in Arctic permafrost regions. Gas hydrate remains stable only under low temperature and relatively high pressure.

IODP co-chief scientist Timothy S. Collett of the U.S. Geological Survey states, “After repeatedly recovering high concentrations of gas hydrate in sand-rich layers of sediment, we’re reporting strong support for sediment grain size as a controlling factor in gas hydrate formation.” Prior to drilling, the scientists anticipated that gas hydrate would be more concentrated at deeper levels below the seafloor and more evenly distributed among the various grain sizes comprising the sediments.

The Integrated Ocean Drilling Program (IODP) is an international marine research program dedicated to advancing scientific understanding of the Earth, the deep biosphere, climate change, and Earth processes by sampling and monitoring sub-seafloor environments. IODP is supported by two lead agencies: the U.S. National Science Foundation, and Japan’s Ministry of Education, Culture, Sports, Science, and Technology. Additional support comes from a European consortium of 17 countries, the People’s Republic of China, and South Korea. U.S.-sponsored IODP drilling operations are conducted by the JOI Alliance; comprised of the Joint Oceanographic Institutions, Texas A & M University Research Foundation, and Lamont-Doherty Earth Observatory of Columbia University.