Antarctic geological evidence of link to North America.

In an interesting finding from the University of Minnesota-Duluth. A lone granite boulder found against all odds high on the top of a glacier in Antarctica may provide additional key evidence to support a theory that parts of the southernmost continent once were connected to North America hundreds of millions of years ago

UMD Professor of Geological Sciences, John W. Goodge and UMD masters student, Devon Brecke (along with five other scientists from the United States and Australia) conducted a research expedition with startling findings. The research of the UMD-led team (in 2005) confirms a hypothesis that Antarctica and North America were connected to one another about one billion years ago.

This provides physical evidence that confirms the so-called southwestern United States and East Antarctica (SWEAT) hypothesis.

The boulder was found while the researchers were picking though rubble carried through the Transantarctic Mountains by ice streams-rivers of ice-that flow at literally a glacial pace from East Antarctica. Goodge and his team were searching for rocks that might provide keys to the composition of the underlying continent crust of Antarctica, which in most places is buried under almost two miles of ice.

Subsequent chemical and isotopic tests conducted in laboratories in the United States revealed that the boulder had a chemistry “very similar to a unique belt of igneous rocks in North America” that stretches from what is now California eastward through New Mexico to Kansas, Illinois and eventually through New Brunswick and Newfoundland in Canada.

That belt of rocks is known to have been a part of what is called Laurentia, which was a component of the supercontinent of Rodinia.

“There is a long, linear belt of these igneous rocks that stretches across Laurentia. But ‘bang’ it stops, right there at the (western) margin where we knew that something rifted away” from what is now the West Coast of the United States,” Goodge said.

“It just ends right where that ancient rift margin is,” Goodge said. “And these rocks are basically not found in any other part of the world.”

This fascinating research was funded by the National Science Foundation and can be explored further in the July 11 edition of the journal Science, at:

http://www.sciencemag.org/cgi/content/full/sci;321/5886/235

PHOTO OF THE DAY:

Collecting specimens in Antarctica

John Goodge and a colleague collecting specimens in the Transantarctic Mountains.

Credit: John Goodge / University of Minnesota-Duluth

The Transantarctic Mountains where the boulder was found.

Credit: John Goodge / University of Minnesota-Duluth

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~ by abstraktbiblos on Tuesday, 29 July, 2008.

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