Geologists map rocks to soak CO...(generally form in earth's mantle startin...)

Date:3/5/2009

generally form in earth's mantle, starting some 12 miles under the surface and extending down hundreds of miles. Bits of these rocksperidotite, dunite, lherzholite and others-- may be squeezed to the surface when continental plates collide with oceanic plates, or, less often, when the interiors of continents thin and develop rifts. Because of their chemical makeup, when the rocks are exposed to carbon dioxide, they react to form common limestone and chalk. A map accompanying the report shows that most such rocks are found in and around coastal mountain ranges, with the greatest concentrations in California, Oregon and Washington, and along the Appalachians from New England to Alabama. Some also occur in the interior, including Montana. Worldwide, other formations are scattered across Eurasia and Australia.

Klaus Lackner, who directs the Lenfest Center, helped originate the idea of mineral sequestration in the 1990s. The U.S. survey is the first of what Lackner hopes will become a global mapping effort. "It's a really big step forward," he said. Krevor produced the map as part of his PhD. dissertation, with help from another Columbia student, Christopher Graves, and two USGS researchers, Bradley Van Gosen and Anne McCafferty. By combining more than a hundred existing maps, the researchers were able to pinpoint the areas nationally where ultramafic rocks are most abundant.

Another rock, common volcanic basalt, also reacts with CO₂, and efforts are underway to map this in detail as well. The U.S. Department of Energy has been working on a basalt atlas for the northwestern United States as part of its Big Sky Carbon Sequestration Partnership; extensive mapping in Washington, Oregon and Idaho has already been done through Idaho State University.

The major drawback to natural mineral carbonation is its slow pace: normally, it takes thousands of years for rocks to react with sizable quantities of CO₂. But scie
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Contact: Kim Martineau kmartine@ldeo.columbia.edu 845-365-8708 The Earth Institute at Columbia University Source:Eurekalert

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