The impactor (most likely an asteroid) formed the Vredefort crater much larger than previously believed.
Researchers have developed a more accurate simulation of the impact that formed Earth’s largest crater Vredefort nearly two billion years ago. They found that the impactor (most likely an asteroid) formed the Vredefort crater much larger than previously believed.
But according to new research from the University of Rochester, the impact could be much larger and would have devastating consequences across the planet. This study, published in the Journal of Geophysical Research, provides a more accurate understanding of large impacts and will allow researchers to better simulate events that impact The earth and other planets, both in the past and in the future.
Natalie Allen ’20, now a PhD student at John Hopkins University, said: “Understanding the largest impact structure we have on Earth is very important. Allen is the first author of the paper, based on research she did as an undergraduate at Rochester with Miki Nakajima, a assistant professor of Earth and environmental science. “Having access to the information provided by a structure like the Vredefort crater is a great opportunity to test our model and our understanding of the geological evidence so we can better understand more about the impact on the Earth and beyond.”
Over the course of two billion years, the Vredefort crater has been eroded. This makes it difficult for scientists to directly estimate the size of the crater at the time of the initial impact, and thus the size and velocity of the crater-forming impact.
An object 15 kilometers in size and traveling at 15 kilometers per second would create a crater about 172 kilometers in diameter. However, this number is much smaller than current estimates for the Vredefort crater. These current estimates are based on new geological evidence and measurements that estimate that the original diameter of the structure would have been between 250 and 280 kilometers (between 155 and 174 miles) during the time of the impact. .
Allen, Nakajima and their colleagues conducted simulations to match the updated dimensions of the crater. Their results suggest that an impactor would have to be much larger – about 20 to 25 km – and travel at 15 to 20 km/s to explain a crater 250 km in size.
This means that the impact of forming Vredefort crater will be greater small planet killed the dinosaurs 66 million years ago, forming the Chicxulub crater. That impact caused harm across the globe, including greenhouse heating, widespread wildfires, acid rain and ozone depletion, in addition to the killing Cretaceous-Paleogenian extinction event. dinosaur species.
If the Vredefort crater were even larger and more impactful than the impact that formed the Chicxulub crater, the Vredefort collision could have even more catastrophic global consequences.
“Unlike the Chicxulub effect, the Vredefort effect does not leave record “Mass extinction or wildfire caused by only single-celled life forms and no trees existed two billion years ago,” says Nakajima.
Dust and aerosols from the Vredefort collision will spread across the planet and block sunlight, cooling the Earth face, she speaks. “This can have devastating effects on photosynthetic organisms. After dust and aerosols settle – which can take anywhere from a few hours to a decade – greenhouse gases such as cardon dioxide are emitted from the atmosphere. The collision will raise global temperatures potentially by several degrees over a long period of time.”
The simulations also allowed the researchers to study the material ejected by the impact and the distance the material traveled from the crater. They can use this information to determine the geographic location of land masses billions of years ago. For example, previous research identifying material from the impact was shipped to present-day Karelia, Russia. Using their model, Allen, Nakajima and their colleagues found that, two billion years ago, the distance of the Karelia-bearing land mass would have been only 2,000 to 2,500 kilometers from the crater in South Africa – closer. more than the two regions. today.
“It’s been very difficult to pinpoint the location of the land masses long ago,” says Allen. “The current best simulations have been mapped for about a billion years, and the uncertainty grows as you go further. Clarifying evidence such as this ejecta layer map could allow astronomers research tests their model and helps refine views of the past.”
The idea for this paper arose as part of a final for the planetary Interiors course (now named Physics of Planetary Interiors), taught by Nakajima, whom Allen attended as a teenager. is a pupil.
Allen says the college experience that resulted in a peer-reviewed journal article was very rewarding and helped her when applying for graduate school.
“When Professor Nakajima approached me and asked if I wanted to work together to make it a publishable work, it was really gratifying and valuable,” says Allen. “I came up with my own research idea, and it was deemed compelling enough to other scientists that they thought it was worth publishing!”
She added, “This project is outside of my usual research comfort zone, but I think it will be a great learning experience and will force me to apply my skills in a new way. It gave me a lot of confidence in my research abilities as I prepared for graduate school.”
