The hottest rock discovered in Earth's crust was first found in 2017 and reported the same year in research published in the journal Earth and Planetary Science Letters. At the time, it was reported that the rock had been formed at temperatures as high as 2,370 °C, hotter than much of Earth's mantle.
Recently, a new rock analysis has shown that the veracity of this record is real. The rocks analyzed belong to the Mistastin crater, located in Labrador, Canada.
The crater, which was formed 6 million years ago and is 28 kilometers wide, was part of a study funded by the Canadian Space Agency that showed how to coordinate astronauts and rovers in the exploration of other planets.
The confirmation of the temperature of the hottest rock
When researchers analyzed the rock found in Mistastin crater, which looks a lot like lunar craters, zircons, an extremely durable mineral that crystallizes when it is exposed to high temperatures, was found in it.
By analyzing the structure of a zircon, it's possible to figure out the temperature they formed. To do this, postdoctoral researcher Gavin Tolometti of Western University in Canada and colleagues analyzed four zircons that came from the crater in samples of different types of local rocks to provide a more comprehensive view of how the impact heated the ground.
Among the samples, one was from a glassy rock that formed on impact, two other samples belonged to rocks that melted and solidified, and one was from a sedimentary rock that contained glass fragments formed on impact.
The results of the analysis showed that the glass zircons were formed at a temperature of 2,370 °C, just as the 2017 research indicated. In addition, the current research showed that the sample collected from the glass sedimentary rock was heated to a temperature of 1,672 °C.
The importance of discovery
The confirmation of the hottest rock temperature made by the scientists, also helped the researchers to better narrow down the locations where superheated rocks are sought after.
"We are starting to realize that if we want to find evidence of such high temperatures, we need to look at specific regions rather than randomly selecting an entire crater," Tolometti said in a statement.
In addition, the researchers also found a mineral called reidite inside the crater's zircon grains. The reidites are formed when zircons undergo high temperatures, and their presence allows scientists to more accurately calculate the pressures the rocks experienced in the impact.
These findings, made in the study of the hottest rock, can also be used on other craters on Earth. "It could be a step forward to try to understand how rocks have been modified by impact craters throughout the solar system," Tolometti said.