Were Antarctica and North America Once One Continent? A Single Boulder Says "Yes"

The continual shifting of continents has led to the theories that, as in the cases of Pangaea and Rodinia, many, if not all of our continents, were at one time or another connected. One particular theory evolving from this is the SWEAT theory, standing for southwestern United States and East Antarctica, which theorizes that the southwestern United States was at one time connected to East Antarctica.

John Goodge, an NSF-funded researcher with the Department of Geological Sciences at the University of Minnesota-Duluth, and his team published a paper that details findings that they believe add considerable weight to SWEAT.

Goodge and his team were conducting a search for rocks that might provide links to the composition of the underlying continental crust of Antarctica. "We were picking up boulders in the moraines that looked interesting," Goodge said. "It was basically just a hodge-podge of material."

One of the rocks that they picked up turned out to be, later, a very specific form of granite with, as Goodge describes it, "a particular type of coarse-grained texture." Chemical and isotopic tests conducted by the team in laboratories in the US revealed the boulder to have 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.

This particular belt of rocks is known to once have been part of Laurentia, a component of what was once 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, and these rocks are basically not found in any other part of the world."

Goodge notes that there is no real alternative explanation for how the rock got to where it was, other than a once continental meet with southwestern United States. The rock had been, as Goodge describes it, “bull-dozed over from that interior region of Antarctica,” thanks to ice streams which slowly pushed rubble underneath them as they moved.

"This is first-rate work and a fascinating example of scientists at work putting together the pieces of a much larger puzzle," said Scott Borg, director of the division of Antarctic sciences in NSF's Office of Polar Programs. "Not only do the authors pull together a diverse array of data to address a long-standing question about the evolution of the Earth's crust during a critical time for biological evolution, but the research shows how the ideas surrounding the SWEAT hypothesis have developed over time."

Posted by Josh Hill.

http://www.eurekalert.org/pub_releases/2008-07/nsf-asb071708.php

Comments

[claudio]

Agreed 100%.

Yes in Pangea model the South america and North america were on the west side of the megacontinent according to the best simulations available.

If another proof of concept comes in Now then it is confirmed.

Again in next 200-250 Million Y the megacontinent will form again (Pangea Nr 2) IF the plates movements will not get crazy and change again.

Every 250Millions Y there is a Mass Exctinction of vast nature ...Kind of an ELE of magnitude 1.

Regards to all

Interesting .....

[Craig]

It is a good thing that all of this plate tectonic moving around stuff takes place over such a long time or you would never be able to get insurance for your house.

[Andrew D Mackay]

I have built a model of a smaller Earth (70%) of its present size and all the continents fit together surprisingly easily - particularly - taking into account the greater curvature of a smaller globe. This model can be seen on my website, evolutionem.co.uk and indeed Antarctica's eastern side fits against the western edge of North America. The model also suggests that much of Antarctica has been pressed down below sea-level - by a previous weight of ice from a large ice cap. According to the model, Antarctica today is only 75 per cent of its previous size. Interestingly, Google bathygraphic maps show a submerged shelf which could be this submerged part of Antarctica. The North Side of Antarctica was joined to the coast of China while its western side was joined to South America's western coast. This is all very difficult to picture in one's head and can only be scrutinised from a 3d model.

My theory is - if you remove all the new ocean beds formed from the mid-ocean ridges you gradually bring the continents together - but this can only be done by reducing the radius of the Earth at the same time.
This makes Pangea the original integument of the Earth at about 1 billion years ago. Another, Earth Expansionist, Dr. Maxlow has reduced the Earth to 50% in order to accomodate the small supercontinent Rodinia. If this is true, Rodinia grew into Pangea by magma outpourings and not by tectonics and they only started when the Earth's integument ruptured.