Methane Hydrate

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Methane Hydrate
Depth - about 1000 m
Suess and Thompson, 1999
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Oregons continental shelf is an active margin
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• In contrast, the east coast continental shelf is
  a passive margin.
• Both can and do have deposits of gas hydrates.

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Methane plumes in the ocean overlying the
deposits at Hydrate Ridge off the coast of
Oregon. Methane hydrate deposits that are
actively deforming in the accretionary prism and
releasing unknown amounts of carbon into the
overlying ocean and atmosphere. Further,
estimates of global abundance of methane hydrate
are in the range 15 Gigatons, a value that has
caused government, industry, and academic groups
to begin considering the resource potential of
these volatile deposits. These formations appear
to be common to the continental slope in many
environments around the world. The hydrate
systems off the Oregon coast promise to become
one of the major study areas in the world for
this kind of work
Water
Seafloor
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Gas Hydrates and associated macrofauna on the
seafloor. Microbial populations in these systems
utilize methane and sulfate as nutrient sources
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Vent fauna community in a box corer sample found
at Hydrate Ridge.
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Ocean sediments as a resource

• Ocean sediments contain many important resources,
  including
• Petroleum
• Gas hydrates
• Sand and gravel
• Evaporative salts
• Phosphorite
• Manganese nodules and crusts

Offshore drilling rig
Figure 4-21
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Clathrate/Methane Hydrates and Climate Change

• Methane (CH4) is a much stronger greenhouse gas
  than carbon dioxide. It is usually released from
  swamps or through biomass burning. But it is also
  trapped in huge amounts in some ocean-floor
  sediments, where it lies buried in a strange kind
  of ice known as 'methane clathrate'. These
  clathrates are stable only within a certain range
  of temperatures and pressures when brought to
  the surface, they melt rapidly and release
  burnable gas to the air.
• A catastrophic release of trillions of tonnes of
  methane is thought to have triggered a
  temperature jump some 55 million years ago in an
  already warm climate at the Palaeocene/Eocene
  boundary (see ' Gas leak!'). But some scientists
  suspect that similar methane bursts, triggered
  perhaps by submarine landslides, sea-level drops
  or changes in water temperature, may also have
  caused a number of rapid warming episodes during
  and at the end of the last glacial period.

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