Asteroids that hit Earth 2.2 billion years ago could cause Earth to “unfreeze”

The discovery of the ancient Yarabuba crater in Western Australia may explain how the most intense ice period on Earth ended, according tomedia CNET. The Yaraba crater, 43 miles (70 kilometers) in diameter, suggests that Earth may have been hit by an asteroid 2.2 billion years ago. Violent impacts could change the Earth’s climate by spraying dust and water vapor into the atmosphere and improving the planet’s ability to absorb heat.

The new study, published Tuesday in the journal Nature Communications, details the work of an international team of collaborators. They include researchers from curtin University of Western Australia and NASA’s Johnson Space Center, who used uranium lead dating to determine the exact age of rocks in the area, based on how elements get trapped inside one of the most accurate dating projects. After the impact, the internal crystals melt and then recrystallize – which is the key to revealing the exact age of the impact crater.

Chris Kirkland, a geoscientist at Curtin University and co-author of the study, said: “We analyzed these individual, small zircon grains in the impact structure – these tiny crystals grow during the impact. The team’s analysis puts the time of impact at 2,229 million years, making it the oldest impact structure on Earth. This also means that impacts can occur as the Earth experiences relatively dynamic changes.

Scientists believe that from about 240 to 2.1 million years ago, a major ice age occurred in Earth’s history, causing the Earth to freeze completely. This situation is often referred to as the “snowball Earth” because from space, our planet may look like a giant snowball floating in the universe.

Nicholas Timms, another geoscientist at Curtin University, said: “The age of the Yarabuba crater matches the time of the demise of a range of ancient glaciers. After the impact, there were 400 million years of rock deposits in the rock record. This ‘turn of fate’ suggests that a huge meteorite impact may have affected the Earth’s climate. “

The researchers modeled the possible effects of craters using computational software. If an asteroid with a diameter of about 4.5 miles (7 kilometers) hits Earth, it could lead to craters similar to the one in Yaraba. It also suggests that such an impact could cause about 5 trillion tons of water vapor to be sprayed into the atmosphere.  However, the team concluded that it was difficult to model the interactions of ancient Earths.

The findings were first reported in the journal Science in August 2019, after the team presented their findings at the Goldschmidt Geochemistry Conference in Barcelona. At the time, Andrey Bekker, a geologist at the University of California, Riverside, wondered whether the impact would cause the Earth to “defrost” alone.