An asteroid that killed dinosaurs could penetrate the Earth's crust

An asteroid that killed dinosaurs could penetrate the Earth's crust

The space stone that broke the domination of the dinosaurs may have passed through the planet deeper than we thought.

After analyzing the crater from the impact that put an end to the existence of dinosaurs, scientists now believe that an object crashing into the planet may have gone all the way through the earth's crust. This is evidenced by a new study.

This discovery can shed light on how the consequences could change the face of the planet and how such collisions can generate new habitats for life.

Asteroids and comets sometimes crash into Earth. However, changes to the planet’s surface are largely due to erosion from rain and wind, as well as “plate tectonics that create mountains and oceanic trenches,” said study co-author Sean Gulik, a marine geophysicist at the University of Texas at Austin .

In contrast, on other rocky planets of the solar system, erosion and plate tectonics are usually weak (if such an influence exists at all) affect the surface of the planet. “The key factor for their change is the constant space attacks,” said Gulik.

Scientists in the new study looked at terrestrial features in order to learn more about the effects of exposure found in other objects of the solar system. In their centers, large craters sometimes have rings of rocky hills. Most of these “peak rings” exist on extraterrestrial rocky bodies, such as Moon or Venus, which complicates the process of detailed analysis of these structures and understanding their origin. To learn more about peak rings, scientists explored a giant crater on Earth, covering more than 110 miles (180 km) and located near the town of Chicxulub on the Mexican Yucatan Peninsula. This crater was formed as a result of an epic fall of an object about 6 miles (10 km) in size and is believed to have interrupted the existence of dinosaurs about 65 million years ago.

Researchers have focused on this crater, since only it has an intact peak ring on the planet. In contrast, the larger terrestrial craters (Sandbury in Canada or Vredefort in South Africa) are “highly eroded — none have peak rings,” said Gulik. - "On the other hand, the peak ring Chiksuluba completely preserved."

Structures that scientists wanted to explore were under water for 60 feet (18 m) in the Gulf of Mexico. In order to collect the samples, the scientists arrived at the place in the spring of 2016 in the “descent ship”, which installed the supports on the seabed and lowered the boat into the water for about 50 feet (15 m). Then the launching ship lowered the drills and “drilled the crater for two months to a depth of 1,335 meters (4,380 feet) under the seabed,” said Gulik. (Pulling up the boat helps to avoid waves that can rock the ship and rig the rigging).

In samples of the peak ring, they found granite, which was deeply buried about 500 million years ago. “These rocks rose to the surface of the Earth within the first few minutes after the impact,” said Gulik. “It speaks of a high degree of shock from the blow.” After the collision, “the land there behaved like a slowly moving fluid,” says Gulik. “A rocky asteroid created a hole, probably with a thickness into the earth’s crust — almost 30 km (18 miles) and 80-100 km (50-62 miles) wide.”

And just as the liquid behaves, the earth quickly began to flow to fill the hole. This means that the sides of the crater should collapse inward.

“At the same time, the center of this hole begins to reach for the top. For example, if you throw a stone into a river, you will notice how a drop rises in the middle, ”said Gulik. “The center would have risen as much as 15 km (9 miles) from the earth’s surface, and then became unstable to gravity and collapsed.”

As a result, the process ends with the formation of a ring of mountains or peak rings.

The research results support one of two main hypotheses describing the formation of peak rings. The first assumes that peak rings occur closer to the surface. As the impact shows, a peak forms in the middle of the crater, and its highest part melts, causing the material to disperse along the peak ring. The second hypothesis suggests that peak rings are formed due to a deep blow to the target, which, as it were, digs up the ground.

“It turns out that models based on deeper origins have gained the right of precedence,” said Gulik. “The findings are based on what we know as hydro-modeling models used to simulate nuclear bombs. These models mimic an asteroid that hits the target at a speed of 20 km per second (44,740 miles per hour), which can cause the crust to flow. ” The researchers noted that the rocks from the peak rings “radically changed their way up when struck,” said Gulik. “They end up with lower density and porosity ranging from 1-2% to 10%.”

These changes may be crucial for the evolution of life on Earth and, possibly, on other planets. “When you get stones with a 10% larger pore space, microbial life that lives below the surface can find new habitats already on the surface,” said Gulik. “We’re going to explore ecosystems to see if we can start working with craters.”

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