Chang’e-5 samples show how young volcanism originated on the Moon

(ORDO NEWS) — A new study by Professor Chen Yi and colleagues at the Chinese Academy of Sciences provides an answer to the question of how young volcanism on the Moon began.

The researchers found that lowering the melting point of the mantle due to the presence of low-melting components could lead to early lunar volcanism.

Their findings were published in the journal Science Advances on October 21.

The lunar samples brought back by the Apollo and Luna missions are older than 3 billion years, so scientists believed the Moon has since been geologically dead.

However, samples collected by China’s Chang’e-5 mission in 2021 revealed young volcanic activity that is only 2 billion years old.

For a small rocky moon, the heat fueling volcanic activity must have been lost long before these eruptions 2 billion years ago.

So what happened? Scientists have previously speculated that either increased water content or heat-producing elements in the Moon’s interior could have caused volcanism during the Moon’s late life.

But the Chang’e-5 data, published in the journal Nature, refuted these hypotheses.

“The recent melting of the lunar mantle could be caused by either a rise in temperature or a decrease in the melting point.

To better understand this problem, we must estimate the temperature and pressure at which young volcanism arose,” said Professor Chen Yi.

The researchers ran a series of simulations of fractional crystallization and melting of the lunar mantle to compare 27 Chang’e-5 basalt samples with Apollo basalts.

They found that the young Chang’e-5 magma contained higher amounts of calcium oxide and titanium dioxide than the older Apollo magmas.

Since late-stage lunar magma ocean accumulations are rich in calcium and titanium and are easier to melt than early-stage accumulations, the addition of these low-melting components to the lunar interior as a result of gravitational mantle flip could effectively reduce the mantle melting temperature and thus provoke a young lunar volcanism.

“We found that the Chang’e-5 magma formed at the same depths, but 80 degrees Celsius colder than the older Apollo magmas.

This means that the lunar mantle experienced a steady, slow cooling of 80°C from about 3 billion years to 2 billion years ago,” said Dr. Su, co-author of the study.

This work provides evidence for the first viable explanation for young lunar volcanism that is compatible with the recently returned Chang’e-5 samples.

This study could help planetary scientists better understand the thermal and magmatic evolution of the Moon.

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