A 52-foot-high “Mega Ripple” from a dinosaur-killing asteroid hides under Louisiana

An ancient “mega-ripple” about the height of a five-story building is hidden deep in Louisiana, indicating that its unique geology was formed shortly after the asteroid strike that killed non-birds. I will. dinosaur, A new study was found.

The 52-foot (16-meter) high Mega Ripple is approximately 5,000 feet (1,500 m) below the Iatt Lake area in north-central Louisiana. Cretaceous Researchers said 66 million years ago when that part of the state was underwater. The size and orientation of the Mega Ripple suggests that a giant space rock known as the Chicxulub asteroid was formed after it crashed into the Yucatan Peninsula. Chicxulub collision tsunamiResearchers then said the waves rushed into the shallows, creating huge ripples on the ocean floor.

“Ripples of that size mean that something very large had to disturb the water column,” said Gary Kinsland, a senior researcher at the University of Louisiana at Lafayette, a professor of earth sciences. I told Live Science. “This is further evidence that the influence of Chicxulub has ended the Cretaceous.”

Relation: Image: How North America grew as a continent

The project began when energy company Devon Energy conducted a 3D seismic exploration of Iatt Lake. Seismic exploration provides surface detectors that can generate large sound waves (often made of “explosives or large lumps”) and capture the returning sound waves that are reflected when they hit various underground rock formations. Place it around the area. Data from these sound waves allow researchers to map underground geology.

Kaare Egedahl, a collaborator in the Master’s Program in Petroleum Geology at the University of Louisiana at Lafayette, obtained Devon Energy data and created seismic images of underground areas. “Kale brought it to me and he said,’What is this?’Because it is very different from what is found in sediments in the sea and rivers.” “I saw it and went to’OMG’.”

A black-and-white seismic image of Mega Ripple created for a master’s thesis by research collaborator Kaare Egedahl. Seismic images cover an area of ​​approximately 11 x 7 miles (18 x 11 kilometers). (Image credit: Kinsland, GL. Etal. Earthand Planetary Science Letters (2021); Kaare Egedahl)

Kindsland had previously studied the Chicxulub crater. When he saw the image of the earthquake, “I immediately saw the ripples, and I soon knew the direction in which the water would have had to go. [to create them]”And if you retreat from it, I knew you would run right in Chicxulub,” he said.

Kindsland was able to pinpoint the direction of the tsunami due to the asymmetrical megaripple. This shows the direction in which the water was flowing when the Mega Ripple was created. In this case, the long, asymmetrical side of the megaripple has a south-southeast slope, which points to the Chicxulub crater, he said.

This map shows the location of the Chicxulub crater (red arrow) and the newly discovered megaripple (red star), most likely left by the tsunami caused by the asteroid’s collision 66 million years ago. is showing. The numbers represent the tsunami deposits previously identified from the event. (Image credits: Kinsland, GL. Etal. Earthhand Planetary Science Letters (2021); Ron Blakey / Colorado Plateau Geosystems; Original basemap by Nina Zamanialavijeh)

The average wavelength of megaripple (from one peak to the next) is 1,968 feet (600 m). It, combined with their 52-foot-high amplitude, makes them “the largest ripples recorded on Earth,” the researchers wrote in their research.

In addition, these megaripples are located above the 66-million-year-old Cretaceous / Paleogene geological boundary, below a layer of debris kicked in the aftermath of the Chicxulub impact, researchers study. I am writing in.

Relation: Wave of Destruction: The Largest Tsunami in History

How did Mega Ripple last?

Huge ripples occur when a tsunami rushes across the Gulf of Mexico after Space Rock hits Earth 66 million years ago, “reaching the sudden shallows of what is now the Gulf of Mexico in central Louisiana.” It shows that it struck shallow water and collapsed offshore. The researcher wrote in the study. “The resulting pulse of water flowing north-northeast through the ledge area produced an asymmetric megaripple imaged in the seismic data.”

However, the small ripples left by the waves on the beach are short-lived. So how did Mega Ripple last for 66 million years?

After the tsunami made huge ripples, they stayed in the water. They were deep enough in the water, and when the storm struck the Gulf of Mexico, the giant ripples remained undisturbed, Kinsland said. Then, over a period of about 5 million years during the Paleocene era (66-56 million years ago), megaripple was formed by shale (essentially sedimentary rock made of mud mixed with clay and mineral fragments). He said it was buried. .. Later, he added, the shale was covered with younger sediments.

This study was published online in the journal on July 2nd. Earth and Planetary Science Letter..

Originally published in Live Science.

A 52-foot-high “Mega Ripple” from a dinosaur-killing asteroid hides under Louisiana

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