SWEAT (hypothesis)

Source: Wikipedia, the free encyclopedia.


SWEAT (which stands for Southwestern United States and East Antarctica) is the hypothesis that the Southwestern United States was at one time connected to East Antarctica.

The hypothesis of a late

ophiolitic belt of the latter may extend into East Antarctica. The Wopmay orogen of northwest Canada may extend through eastern Australia into Antarctica and thence beneath the ice to connect with the Yavapai-Mazatzal orogens of the southwestern United States. Counterparts of the Precambrian-Paleozoic sedimentary rocks along the U.S. Cordilleran miogeocline may be present in the Transantarctic Mountains. Orogen boundaries provide useful piercing points
for Precambrian continental reconstructions.

The

Appalachians
.

Evidence

A paper published by an international team of U.S. and Australian investigators led by John Goodge gives significant support to the theory.[1][2] The team's findings were made in the Transantarctic Mountains and provide physical evidence that confirms the SWEAT hypothesis.[2]

The team was searching in Antarctica's Transantarctic Mountains for rocks carried along by ice rivers that could provide clues to the composition of the underlying crust of Antarctica, which in most places is buried under approximately 3,200 meters (2 mi) of ice. One rock, found atop

rapakivi texture.)[3][2][4] Chemical tests run on the rock revealed that it has a radiometric age and stable isotope ratios closely matching those of a distinctive belt of rapakivi granite in North America that stretches from California through New Mexico to Kansas, Illinois in the United States, and eventually New Brunswick and Newfoundland in Canada.[3]
This belt of rock was a part of Laurentia, thought by some geologists to be the core of Rodinia.[5] This belt stops suddenly at its western margin, leading geologists to suspect that some piece of crust had rifted away from what is now the West Coast of the United States.[2][4][3]

East Antarctica–Laurentia juxtaposition

The positions of Laurentia and other landmasses in the Precambrian

detrital zircons
match those in Laurentian granites of similar age; and a glacial clast of A-type granite has a uranium-lead zircon age of c.1440 million years, an epsilon-hafnium initial value of +7, and an epsilon-neodymium initial value of +4. These tracers indicate the presence of granites in East Antarctica having the same age, geochemical properties, and isotopic signatures as the distinctive granites in Laurentia.

References

  1. ^ Hill, Josh Hill (July 18, 2008). "Were Antarctica and North America Once Connected? A Single Boulder Says "Yes"". The Daily Galaxy. Retrieved 2008-07-29.
  2. ^ a b c d "A Single Boulder May Prove that Antarctica and North America Were Once Connected". National Science Foundation. July 17, 2008. Retrieved 2008-07-29.
  3. ^
    S2CID 11799613
    . Retrieved 2008-07-29.
  4. ^ a b Thompson, Andrea (July 28, 2008). "Senior Writer". LiveScience.com. Archived from the original on August 13, 2008. Retrieved 2008-07-29.
  5. ISBN 9781405107778
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=SWEAT_(hypothesis)&oldid=1186235173"