As a result of the fall of the meteorite in Lake Quebec, rare stones appeared

For more than ten years, Western University planetary geologist Gordon "Oz" Osinski led expeditions to Lake Kamestastin in Labrador. The environment is an ideal training ground, as the features and rock formations created by the powerful impact (and intense heat) of an asteroid 36 million years ago uniquely mimic the surface of the Moon.

Osinski, Niraja Chinchalkar, a research technician at the Western Laboratory for Earth and Planetary Materials Analysis (EPMA), and their colleagues have now uncovered new evidence that the impact of another meteorite once produced equally extreme (and thus rare) high temperatures exceeding 2,370 ° C (4172°F), on another remote impact structure in northern Quebec.

For the study, published in 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 a scanning electron microscope. The analysis revealed evidence of natural cubic zirconia, a mineral that requires temperatures of at least 2370°C to form. To put this into perspective, lava flows from volcanoes on Earth range from about 800°C to a maximum of about 1200°C.

"We looked at the structures present in 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 terrestrial rocks. left behind unique space-modified specimens that can be studied for years to come and will only contribute to our understanding of the cosmos», — said Chinchalkar.

Field photos of the sampling sites. A: Sample 1 was collected from a glassy dike in a breccia-bearing melt; B: Close-up of the glass dam; C: Outcrop of molten rock with a large fragment of host rock. The white square shows the location (D). D: close-up of the area marked by the square in C; sample 2 was collected from the cooled vitreous rim. The handle at the bottom left is for zoom. Credit: Earth and Planetary Science Letters (2024). DOI: 10.1016/j.epsl.2024.118714
While previous studies have shown that molten material from meteor impacts can reach such extreme temperatures, there has been little direct evidence on Earth. In fact, prior to this new study, such evidence had only been found in one meteorite crater: the Lake Kamestastin impact structure.

"Lake Kamestastin contains some of the best-preserved molten rock on Earth, which is one of the top-priority samples that future lunar astronauts want to find and retrieve,— said Osinski, professor of earth sciences. "Now that we have found evidence of these incredible impacts of molten rock at West Clearwater Lake, we have a new place on Earth for astronauts, students and geologists like me to study and learn.

Examination of rock samples at West Clearwater Lake also found evidence of reidite, a mineral that forms under extreme pressures exceeding 20 gigapascals, a measurement of the physical force exerted on an object.

"This discovery highlights the variable and dynamic conditions that occur during the process of melt formation caused by meteorites falling on Earth and beyond", — Chinchalkar said.

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