A Billion Year Old Piece of North America Traced Back to Antarctica

[Judi Lynn]

A Billion Year Old Piece of North America Traced Back to Antarctica
August 09, 2011

Boulder, CO, USA - An international team of researchers has found the strongest evidence yet that parts of North America and Antarctica were connected 1.1 billion years ago, long before the supercontinent Pangaea formed.

"I can go to the Franklin Mountains in West Texas and stand next to what was once part of Coats Land in Antarctica," said Staci Loewy, a geochemist at California State University, Bakersfield, who led the study. "That's so amazing."

Loewy and her colleagues discovered that rocks collected from both locations have the exact same composition of lead isotopes. Earlier analyses showed the rocks to be the exact same age and have the same chemical and geologic properties. The work, published online (ahead of print) in the September issue of the journal Geology, strengthens support for the so-called SWEAT hypothesis, which posits that ancestral North America and East Antarctica were joined in an earlier supercontinent called Rodinia.

The approximately 1.1 billion year old North American Mid-continent Rift System extends across the continent from the Great Lakes to Texas. Volcanic rocks associated with the rift, which appears to represent an aborted tectonic attempt to split the ancestral North American continent of Laurentia, are well exposed in the Keweenaw Peninsula of the Upper Peninsula of Michigan from which they take their name, the Keweenawan large igneous province. The rift extends in the subsurface beneath Minnesota, Iowa, Nebraska, Kansas and Oklahoma to the Franklin Mountains near El Paso, Texas where related rocks are exposed. In this latest report, Loewy, Ian Dalziel, research professor at The University of Texas at Austin, Richard Hanson of Texas Christian University and colleagues from several overseas institutions, find that rocks barely peeking through the ice in Coats Land, a remote part of the Antarctic continent south of the Atlantic Ocean basin, reflect a former continuation of the North American rift system. Loewy began her collaboration with Dalziel several years ago as a graduate student at the University of Texas at Austin.

More:
http://www.brightsurf.com/news/headlines/67793/A_Billion_Year_Old_Piece_of_North_America_Traced_Back_to_Antarctica.html

[Johonny]

1. OMG Antarctica succeeded from Texas

can you blame it?

[dtexdem]

2. Cool.

And I don't just mean Antarctica. ;-)

[immoderate]

3. If you catch my drift...

I get nostalgic for Laurentia.

--imm

[Ian David]

4. Older than McCain! n/t

[laconicsax]

6. Are you sure?

:shrug:

[starroute]

5. Map

[Enthusiast]

7. Thanks.

I've never seen that particular map. This is fascinating stuff (to me). I love learning about plate tectonics -especially about its role in influencing the path of evolution.

[Enthusiast]

8. Thank you, Judi Lynn.

I appreciate you calling this to our attention.