In addition to being one of the seven natural wonders of the world, the Grand Canyon is a book of living history that reveals great geological epochs in its various strata.
Now, Colorado researchers think they have unraveled the mystery surrounding a more than billion-year-old “gap” in this record, known as “The Great Nonconformity.”
In an article published in the journal Geology, they theorize that the rupture of an ancient supercontinent, known as Rodinia, more than 630 million years ago, triggered a series of small but powerful earthquakes that pushed millennia. of rock and feeling in the canyons. east face to the ocean.
“More than a billion years have passed,” lead author Barra Peak, a graduate student in geology at CU Boulder, said in a statement.
“Billions of years also pass during an interesting part of Earth’s history, where the planet is moving from an older environment to the modern Earth we know today.”
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Researchers at the University of Colorado believe that the tectonic disturbance caused by the rupture of an ancient supercontinent contorted the Grand Canyon and created a “gap” of one billion years in its geological record
Rodinia formed about a billion years ago and separated between 750 and 633 million years ago, with its fragments reassembling to end up forming Pannotia, a short-lived pan-African supercontinent.
It is believed that the dissolution of Rodinia cooled the planet and opened the doors to the massive and rapid evolution of primitive life in the Cambrian period, but little is known about the geological history of Rodinia or even about its configuration.
If your breakup is connected to the “Great Nonconformity,” it could shed more light on both.
“The Great Nonconformity is one of the first well-documented geological features in North America,” the author said in a statement, lead author Barra Peak.
“But until recently, we didn’t have many limitations on when or how it happened.”
A recent photograph of the Grand Canyon from the Walhalla Plateau, with the red line showing the Great Nonconformity
The difference in geological strata on the east and west sides of the canyon, known as “The Great Nonconformity,” caused a billion years of rock and the feeling submerged.
Self-taught explorer and geologist John Wesley Powell observed the great dissatisfaction during his historic boat trip on the Colorado River more than 150 years ago in 1869.
Outlining a section of the canyon, he showed how the rocky strata of the Middle and Late Proterozoic era are almost vertical, compared to the horizontal strata above.
Peak, a graduate student in geology at CU Boulder, said the phenomenon shows “beautiful lines” from the Colorado River.
A drawing of a stratigraphic section of the Grand Canyon by John Wesley Powell from 1875. The area of section “B” between “x” and “y” represents the “nonconforming” areas that do not coincide with the direction of the other strata.
“At the bottom, you can see very clearly that there are rocks that have come together,” he said in the statement.
Its layers are vertical. Then there is a boundary, and on top of that you have these beautiful horizontal layers that form the mounds and peaks that you associate with the Grand Canyon.
His team used “thermochronology,” which tracks the history of the heat of the rock left by the pressure of geological formations that are buried deep in the ground.
“We have new analytical methods in our lab that allow us to decipher history in the window of time that is missing through the Great Nonconformity,” said co-author Rebecca Flowers, a geological science professor at CU.
Showing stones from all over the canyon, they found that the western and eastern parts had different heat histories and probably underwent different geological changes over time.
“It’s not a block with the same temperature history,” Peak said.
Judging by the heat levels, the western basement rock came to the surface about 700 million years ago, while the equivalent rock was submerged under miles of sediment.
The big difference was caused by the rupture of Rodinia, Peak said, with earthquakes and “failed events” that contorted the earth in different ways and created the Great Nonconformity.
She and her colleagues are now looking to explore similar periods of lost time in places across North America.