Meteorite impact on Lake Quebec yields rare rocks and evidence of extreme heat

Western University planetary geologist Gordon “Oz” Osinski led expeditions to Lake Kamestastin in Labrador for more than a decade. The environment is a perfect training ground because the features and rock formations – created by the violent impact (and extreme heat) of an asteroid 36 million years ago – uniquely mimic the surface of the Moon.

Osinski, Neeraja Chinchalkar, a research engineer at Western’s Earth and Planetary Materials Analysis (EPMA) Laboratory, and their collaborators have now discovered new evidence that another meteorite impact once produced equally extreme (and in this case rare) high temperatures, exceeding 2,370°C (4,172). °F), on another remote impact structure in northern Quebec.

For the study published by the journal Letters on Earth and Planetary ScienceChinchalkar analyzed glass from rock samples originally collected by Osinski in 2014 at the West Clearwater Lake impact structure in Quebec using an electron microprobe and a scanning electron microscope. The analysis found evidence of natural cubic zirconia, a mineral that requires a temperature of at least 2,370°C to form. To put this into perspective, lava flows from volcanoes on Earth range from about 800°C to a maximum of around 1200°C.

“We looked at the structures present in the zircon grains to reconstruct a meteorite impact event millions of years ago. We found evidence that the target rocks reached extremely high temperatures which, combined with high-pressure conditions, melted and transformed these Earth rocks. They left behind a unique space-modified samples that can be studied for years to come and will only enhance our understanding of the universe,” Chinchalkar said.

While previous research has suggested that molten material from meteor impacts can reach such extreme temperatures, direct evidence on Earth is scarce. In fact, until this new study, such evidence had only been found from one meteorite crater: the Lake Kamestastin impact structure.

“Lake Kamestastin contains some of the best-preserved impact melts on Earth, which are some of the highest-priority samples that future lunar astronauts want to find and collect,” said Osinski, a professor of Earth sciences. “Now that we’ve found evidence of these incredible molten rock impacts at West Clearwater Lake, we have a new destination on Earth to bring astronauts, students and geologists like me to train and study.”

Research on the West Clearwater Lake rock sample also revealed evidence of reidite, a mineral that forms under extreme pressure exceeding 20 gigapascals, a measurement of the physical force exerted on an object.

“This discovery underscores the variable and dynamic conditions that occur during the melt formation process caused by meteorite impacts on and off Earth,” Chinchalkar said.

Reidite has previously been found on only 10 meteorite impact structures on Earth, including Haughton, Nunavut and Steen River, Alberta.