Volcanoes under ice yield climate secrets

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When dealing with the academic topic of "volcanoes," the temptation is to suggest that important research results will erupt and flow.

But for volcanologist Ian Skilling in the University of Pittsburgh's School of Arts and Sciences, that image represents an accurate portrayal of what's likely to result from his three-year research project in Iceland.

Analysis of rock from the Dyngjufjöll mountain -- a volcano that's historically been covered by ice sheets in central Iceland just north of the Vatnajökull ice cap -- promises to provide new detail about the Earth's climate over the past 2.5 million years.

It also could help explain 16 ice ages that occurred over that period of time, including the thickness of the ice sheets and details about Earth's climate during each ice age.

The research succeeds in turning volcanic rock into crystal balls from which climate information can be gleaned.

"The place to study active volcanoes through ice is in Iceland," Dr. Skilling said, noting plans to head there next summer.

Water content of volcanic rock reveals how deep beneath the ice it was when the eruption occurred. Magma -- or molten rock below Earth's surface -- has water dissolved into it at temperatures exceeding 1,000 degrees Celsius. Magma reaching Earth's surface is known as lava.

Lava flow under sheets of ice sometimes 1.5 miles thick are affected by the weight of the ice over it. Once lava cools into volcanic rock, the amount of water remaining in the rock indicates how deep under the ice it was at time of formation.

The deeper under ice, the more water the rock contains. Analyzing the rock along with radio-isotope dating of the rock reveals the thickness of ice sheets in that era. The rock thereby offers considerable information about climate.

The research approach is a new one that's been in use for only a decade. It puts Dr. Skilling and his team at a prime position to provide valuable insights about Earth's climate over millions of years.

Dr. Skilling said such research is possible anywhere volcanoes occur under sheets of ice or ice caps. Such locations include volcanoes in Iceland, Siberia, Antarctica, British Columbia, the western United States and the Andes of South America. Findings can be compared with data collected from volcanoes under the ocean, where water temperatures at the time of eruption also create similar characteristics in volcanic rock.

Details about ice thickness on land prior to the last ice age, which ended about 20,000 years ago, have been lacking, so the new analysis will advance the science.

"One valuable thing about this technique is, it records ice ages on land prior to the last one," Dr. Skilling said. "The current ice age often wipes out evidence of the previous ones, but it doesn't wipe out the volcanic record of the ice on land."

A British native who previously worked at the University of South Africa and with the British Antarctic Survey, Dr. Skilling will work with a team including colleagues from Open University in the UK, the University of Wisconsin at Milwaukee, and the University of Iceland.

Their project has received a $304,000 grant through the National Science Foundation. The team hopes to construct a model to illustrate the interaction between large volcanoes and overlying ice sheets through analysis of textures, chemical composition and age of the rocks.

Because the Dyngjufjöll volcano had been blanketed by at least 16 glaciers, central Iceland could provide the most comprehensive record of Northern Atlantic land ice, Dr. Skilling said. Study results will be "invaluable for depicting bygone climate," and help to model future climate change.

The research also offers additional benefits. Because it's believed that volcanoes on Mars existed under sheets of ice, what is learned about Dyngjufjöll will provide insights about the history of ice on Mars.

Dyngjufjöll, like many Martian volcanoes, involve calderas, which result when magma under a volcano shifts or is ejected, leaving a void that causes the volcano structure to collapse in catastrophic fashion. The result is a hole resembling a cooking pot or cauldron, explaining its name.

Such volcanoes often result in the formation of lakes, such as Crater Lake in Oregon. A lake also was created near Dyngjufjöll when a volcano erupted in 1875.

"Caldera volcanoes such as Dyngjufjöll provide a good comparison of the interaction of this common type of volcano with ice on Mars," Dr. Skilling said. "The largest volcano in the solar system is a caldera volcano on Mars. That volcano, known as Olympus Mons, is three times higher than Mount Everest."

David Templeton can be reached at dtempleton@post-gazette.com or 412-263-1578.


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