Scientists have determined the age of one of the most ancient impact craters of the Earth

(ORDO NEWS) — A huge impact crater hiding deep under the Hiawatha Glacier in Greenland was probably created after a kilometer-wide asteroid collided with Earth 58 million years ago.

Due to the complexity of working in Greenland, scientists have been studying this issue for more than 7 years.

According to scientists, this happened about eight million years after the infamous collision that killed most of the dinosaurs.

The crater, also called Hiawatha, was first discovered in 2015. The researchers suspected that it was formed by a meteorite somewhere between 12,000 and three million years ago.

These dates roughly correspond to the last ice age. The geological features of the crater also hint that the asteroid that created it crashed into an already formed ice sheet.

However, this theory was formed on circumstantial evidence such as radar scans. Since the discovery, scientists have continued to study the crater to determine its true age.

It took so many years, because most of the samples are under a kilometer of ice, it was not easy to collect direct “evidence” of the true age.

How scientists conducted research in ice

Scientists have determined the age of one of the most ancient impact craters of the Earth 2

Using two different dating methods, researchers from Denmark and Sweden eventually came up with the same date.

“Determining the new age of the crater surprised us all,” says geologist Michael Storey of the Danish Museum of Natural History.

“I am convinced that we have determined the actual age of the crater to be much older than many people once thought.”

Evidence of age has come from the banks of rivers downstream of the Hiawatha Glacier, which carry rocks and sand from bedrock under the ice sheet to the open.

Specialists from the National Museum of Natural History in Sweden focused on the rocks on the banks of the river, which contain the mineral zircon.

When a meteorite falls on this mineral, it forms new crystals that include the radioactive element uranium and lead. Studying the ratio of uranium to lead can show exactly when crystallization began.

Researchers from Denmark used the argon-argon dating method. By heating sand collected downstream with a laser, the team was able to release argon gas from individual grains.

The isotopes of this gas helped determine how much radioactive decay has occurred since the minerals were melted by the meteorite impact.

The argon-argon method suggests that the asteroid hit Earth in the late Paleocene, somewhere between 56 and 66 million years ago, while the uranium-lead method suggests 58 million years ago.


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