Quebec lake meteorite impact yields rare rocks and evidence of extreme heat by StuffsEarth

Estimated read time 13 min read

A rare rock sample, containing natural cubic zirconia, from West Clearwater Lake. Credit: Jeff Renaud

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

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

For the study, published by the journal Earth and Planetary Science Letters, Chinchalkar 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 scanning electron microscope. The analysis found evidence of natural cubic zirconia, a mineral which 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 1,200°C.

“We looked at the structures present within zircon grains to reconstruct a meteorite impact event from 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. It left behind unique space-modified samples that can be studied for years to come and will only further our understanding of the cosmos,” said Chinchalkar.

Quebec lake meteorite impact yields rare rocks, heat evidence
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Field photographs of sample locations. A: Sample 1 was collected from the glassy dike within the melt bearing breccia; B: Closeup of glassy dike; C: Outcrop of impact melt rock with a large clast of country rock. White square shows the location of (D). D: Closeup of area marked by the square in C; sample 2 was collected from the chilled, glassy margin. Pen in the bottom left for scale. Credit: Earth and Planetary Science Letters (2024). DOI: 10.1016/j.epsl.2024.118714

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

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

The West Clearwater Lake rock sample investigation 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 process of melt generation caused by meteorite impacts on Earth and beyond,” said Chinchalkar.

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

More information:
Neeraja S. Chinchalkar et al, Zircon microstructures record high temperature and pressure conditions during impact melt evolution at the West Clearwater Lake impact structure, Canada, Earth and Planetary Science Letters (2024). DOI: 10.1016/j.epsl.2024.118714

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