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magazine / ma07
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March/April 2007 issue |
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Salt signals
Domelike deposits mark a motherlode
By Andréa Ventimiglia
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| Click image to enlarge |
Image credit: Earth Observatory, NASA
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The first aerial photos of the Arctic Archipelago, taken
in the 1940s, revealed large, round white domes dotting
some of the islands. The formations, called diapirs, also appear
in the hydrocarbon-rich geology of Iran and the Gulf of Mexico
and so caught the attention of Canadian geoscientists, says
Christopher Harrison, a geologist with the Geological Survey
of Canada in Calgary. Why? Because where there are diapirs,
there is oil and gas.
Two of the white protuberances appear in this Landsat image
of the Sabine Peninsula (right), which reaches into the marbled
sea ice from the northeastern tip of Melville Island. The structures
are created when prehistoric seas evaporate and leave behind large
pockets of salt. As younger, heavier sediments accumulate around
the deposit, they shore up the salt and push it out laterally, forming
island-like domes. Oil and gas can become trapped along the
margins of a diapir or in the sediment above deeper salt deposits.
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| Click map to enlarge |
| Map: Steven Fick / Canadian Geographic |
The Sabine Peninsula generated interest in the 1980s when
scientists discovered the potential for about 224 billion cubic
metres of natural gas — more than three times the amount in
Newfoundland's Hibernia field — just south of the area in this
image. In 2005, the Calgary-based Canadian Energy Research
Institute (CERI) studied the economic feasibility of exploiting
the resource and found that liquefying the gas could help solve
transportation issues and make Canada a major North
American supplier.
"The potential certainly exists," says George Eynon, co-author
of the CERI report. "In the next 5 to 10 years, gas demand is
likely to remain very high, so the resources on Melville Island
are an option that the government and energy companies will
want to explore."
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