Published August 09, 2011
Texas may be suffering through a 100-plus degree heat wave, but long ago, the weather must have been surprisingly different. In fact, Texas and sub-zero Antarctica were linked 1.1 billion years ago, long before the supercontinent Pangaea formed, scientists said Monday.
Rocks collected in a mountain range in West Texas have the exact same composition of lead isotopes as those from Coats Land in Antarctica, a remote part of the Antarctic continent south of the Atlantic Ocean basin, said Staci Loewy, a geochemist at California State University, Bakersfield. Both were once part of a supercontinent that existed long before the famed Pangea -- a giant, early land mass called Rodina, she said.
"I can go to the Franklin Mountains in West Texas and stand next to what was once part of Coats Land in Antarctica," Loewy exaclaimed. "That's so amazing."
The study hinges on the knowledge that the Earth's continents rest on tremendous tectonic plates, and like pieces of a jigsaw puzzle, they have been rearranged several times over the history of the planet -- and likely will be moved and re-sorted again in the future.
The exact order of the plates and what sort of continents were formed by their shuffling may be carved in stone, but our knowledge of that part of the planet's history is still being learned, as geologists sort through the boulders and rubble around us for evidence of history's progress.
Earlier analyses had revealed that the rocks in Texas and Antarctica were the exact same age and have the same chemical and geologic properties. Loewy, Ian Dalziel, research professor at The University of Texas at Austin, Richard Hanson of Texas Christian University and colleagues from several overseas institutions relied on the analysis of lead isotopic data and paleomagnetic data to connect the rocks to the icy waste via a continuation of the North American rift system.
The approximately 1.1 billion year old North American Mid-continent Rift System extends across the continent from the Great Lakes to Texas.
The new finding, which will be published 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 once joined in the supercontinent Rodinia.