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Scientists have reconstructed a long-ago asteroid impact that makes the strike that wiped out the dinosaurs 65 million years ago look like a playful chuck on the chin.
The enormous collision occurred 3.26 billion years ago and involved an asteroid 23 to 36 miles (37 to 58 kilometers) across — four to six times wider than the dino-killing space rock. The impact created a crater about 300 miles (500 km) wide and generated seismic waves far more powerful than those produced by any earthquake in recorded history, researchers said.
The asteroid impact was "far larger than anything in the last billion years," Jay Melosh of Purdue University, who was not involved in the new study, said in a statement. [Wipe Out: History's Most Mysterious Extinctions]
Researchers Norman Sleep and Donald Lowe, both of Stanford University, mapped out the details of the cataclysmic strike after studying rocks in a region of South Africa known as the Barberton greenstone belt.
The space rock probably hit far away from the Barberton formation, in a location that researchers may never find. But it left its imprint on the South African rocks and on the entire Earth, disrupting the planet's crust and possibly spurring a transition from an early tectonic regime to the more modern plate-tectonic system that prevails today, researchers said.
"This is providing significant support for the idea that the impact may have been responsible for this major shift in tectonics," said UCLA geologist Frank Kyte, who was not a member of the study team.
According to Dion, Prof Christoph Heubeck of the Free University of Berlin did a thesis on the rocks of this area. He said the site included the best examples of the most important geological exposures. Some of them was shown on the route, one being formations containing the first microfossil evidence of life on earth, such as stromatolites and biomats, which can actually be seen with the naked eye.
He showed pillow lava balloons indicating widespread underwater volcanic eruptions and spherule beds, remnant of the earliest recorded and probably the largest asteroid impacts on earth.
Carl Sagan and George Mullen identified the paradox in 1972. By then, researchers had determined that a newborn star’s brightness gradually increases over time as hydrogen atoms in the star’s core fuse into helium. Working backward, researchers estimated that the sun generated 20 to 30 percent less energy during the first half of Earth’s history than it does now.