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Alberta Crater May Have Been An Ancient Meteorite Impact Site

May 8, 2014
Image Caption: This is a map showing the structure and contour of the Bow City crater. Color variation shows meters above sea level. Credit: Alberta Geographic Survey/University of Alberta

Gerard LeBlond for redorbit.com – Your Universe Online

Evidence from an ancient ring-like structure discovered in southern Alberta, Canada, suggests it was formed by a meteorite strike. The meteorite was large enough to form a five-mile-wide crater and if a strike of that magnitude occurred today, the resulting explosion would obliterate Calgary.

A research team led by Doug Schmitt, a Canada Research Chair in Rock Physics from the University of Alberta, studied the site discovered by a geologist from the Alberta Geological Survey. According to the findings, most of evidence has been either eroded away or covered by glaciers, making it nearly impossible to disclose 100 percent certainty it was caused by a meteorite strike. However, the seismic and geological evidence does suggest it.

“We know that the impact occurred within the last 70 million years, and in that time about 1.5 km of sediment has been eroded. That makes it really hard to pin down and actually date the impact,” Schmitt said.

A graduate student, Wei Xie, calculated the depth on impact to be one to one-and-a-half miles deep.

“An impact of this magnitude would kill everything for quite a distance. If it happened today, Calgary (200 km to the northwest) would be completely fried and in Edmonton (500 km northwest), every window would have been blown out. Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades,” Xie said in a statement.

The size of the meteorite would had to have been between 980 and 1,600 feet in diameter if it was composed of iron or if it was made of rock it would have been at least 3,200 feet across to cause such a crater. The blast would have been 200 times more powerful than any nuclear device. Anything living within a 124-mile radius would have received first-degree burns, reported CBC News.

The crater was first discovered in 2009 by geologist Paul Glombick while working on a geological map using log data from the oil and gas industry. He checked maps that dated back to the 1940s and found evidence of faulting at the surface.

“It’s exciting to come across a structure like this. It highlights there’s still a fair amount of unknowns in the shallow subsurface,” Glombick said. “It’s nice to be able to contribute something to the geology of Alberta.”

“It was buried, it was just luck. It’s probably one of the most boring places. It’s beautiful, but it’s flatline and in that sense it’s quite boring. All of a sudden, he’s mapping this up, expecting just flat layers. Then this funny, doughnut-shaped thing appears,” Schmitt, who was contacted by AGS to survey the site, explained about the discovery.

During the research the team found some interesting evidence.

“We could see features that you would expect very much from a large meteorite impact. You see great big faults at the edges. When it makes the crater, then the edges of the hole start to slump in, and then, also, what’s really distinctive is the central peak — you get a little mountain in the centre of it. We don’t know exactly how old it is and that’s tied to how big it is. In that area of Alberta, there was much, much more sediments before — about 1.5 to two kilometres of sediments, and they have all been eroded away. We’re pretty confident it can only be a meteorite impact. It’s pretty clear,” Schmitt said in a statement to the Calgary Herald.

Currently the team is looking for minerals that are only found under certain conditions that would prove the crater was formed by a meteorite strike.


Source: Gerard LeBlond for redorbit.com - Your Universe Online



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