A team of University of Wyoming scientists has discovered evidence that the ancient rocks from Wyoming's Teton Range are the result of continental collisions dating back as early as 2.68 billion years ago that were similar to those that created the Himalayas. The study sheds light on the plate tectonics that took in what is now Western Wyoming and reveals that they took place before similar collisions created the Himalayas approximately 40 million years ago. The findings outlined in the study examine rocks found in the Tetons that are likely the oldest remnants of continent-continent collisions.
"While the Himalayas are the prime example of continent-continent collisions that take place due to plate tectonic motion today, our work suggests plate tectonics operated far, far back into the geologic past," Carol Frost, lead author of the paper, said in a press release.
The study conducted analyses on ancient granite that was exposed in the northern Teton Range and compared the results to similar rocks in the Himalayas. These rocks were created during the production of magma through the process of decompression melting, which typically occurs when two continental plates collide. After the thickened crust makes it way under gravitational forces, the deeper crust moves towards the surface and causes melting.
Although the Tetons are a fairly young mountain range that were created by an uplift that took place along the Teton Fault less than 9 million years ago, the study reveals that the exposed rocks are some of the oldest ever discovered in North America.
Furthermore, although the mechanisms that created the Teton granites and the Himalayas are similar, there are significant differences stemming from the composition of the continental crust that was present in Wyoming 2.68 billion years ago - in particular, it possessed less potassium than the more recent Himalayan crust.
The findings were published in the Dec. 31 issue of Geochimica et Cosmochimica Acta.
