(ORDO NEWS) — The hottest rock ever found in the earth’s crust was indeed superhot.
The rock, a fist-sized piece of black glass, was discovered in 2011 and first reported in 2017, when scientists wrote in Earth and Planetary Science Letters that it formed at temperatures as high as 4,298 degrees Celsius. Fahrenheit (2370 degrees Celsius), which is hotter than most of the Earth’s mantle.
Now a new mineral analysis from the same location shows that this record temperature was real.
These rocks were melted and reshaped by a meteorite impact about 36 million years ago in what is now Labrador, Canada.
The impact created the 17-mile (28 km) wide Mistastin Crater where Michael Zanetti, then a doctoral student at Washington University St. planets or moons. (Mistastin crater is very similar to the lunar crater and is often used as a dummy for such studies).
The chance find turned out to be important. Analysis of the rock showed that it contains zircons – extremely durable minerals that crystallize under the influence of high temperature. From the structure of zircons, you can determine how hot it was at the time of their formation.
But to confirm the initial findings, the researchers needed to date more than one zircon. In the new study, lead author Gavin Tolometti, a postdoctoral researcher at Western University in Canada, and colleagues analyzed four more zircons in samples from the crater.
These samples were taken from different rock types in different locations, giving a better idea of how the impact warmed the earth. One sample was taken from glassy rock formed by the impact, two others from rocks that had melted and solidified, and one from sedimentary rock containing fragments of glass from the impact.
The results, published April 15 in Earth and Planetary Science Letters, showed that the glass-bearing zircons were formed at temperatures of at least 4,298 F, as indicated in a 2017 study.
In addition, the glassy sedimentary rock was heated to 3043 F (1673 C). This wide range will help researchers narrow down where to look for the most superheated rocks in other craters, Tolometti said in a statement.
“We’re starting to realize that if we want to find evidence of such high temperatures, we need to look in specific regions rather than picking randomly across the crater,” he said.
The researchers also found a mineral called reidite in the zircon grains from the crater. Reidites are formed when zircon is subjected to high temperatures and pressures, and their presence allows researchers to calculate the pressure the rocks were under when they were impacted.
They found that the impact resulted in a pressure of 30 to 40 gigapascals. (One gigapascal is 145,038 pounds per square inch of pressure). Such pressure must have been at the edges of the collision; in the zone of a direct impact of a meteorite on the crust, the rocks would not only melt, but evaporate.
The results obtained can be used to extrapolate to other craters on Earth – and elsewhere. The researchers hope to use similar methods to study rocks brought back from impact craters on the Moon during the Apollo missions.
“This could be a step forward to try to understand how rocks have changed as a result of impact craters throughout the solar system,” Tolometti said.
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