(ORDO NEWS) — Chinese geologists have found the most logical explanation for the abnormally late volcanism on the moon.
The differences between the rock samples that were brought to Earth by the Apollo and Chang’e-5 missions helped them in this.
Volcanic activity on the natural satellite of our planet is an incredibly interesting topic for scientists. Eruptions do not and cannot occur on the Moon now, its bowels are, in fact, frozen.
But it was not always so. Most importantly, by the time of the cessation of volcanic activity in the past, one can judge the internal structure of the Moon and the processes of its formation.
According to the most firmly substantiated version, about 2.8-2.9 billion years ago, volcanism on the Moon practically ceased.
However, the Chinese unmanned Chang’e-5 mission in 2020 delivered samples of lunar soil to Earth, in which volcanic rocks were present 2.03 billion years ago.
Such a significant gap in the chronology needed to be explained somehow. In simple words, the logic of Chinese scientists was approximately the following.
An eruption requires molten rock, that is, high temperatures and pressure in the bowels. For almost a billion years, the Moon could not maintain a constant temperature in the mantle.
The hypothesis of heating by the decay of radionuclides of rocks with a high water content exists, but it is refuted by the data of the same Chang’e-5 mission.
There was only one option left – a lower melting point of basalts collected by the Chinese apparatus.
This hypothesis was tested by specialists from the Institute of Geology and Geophysics of the Chinese Academy of Sciences ( IGGCAS ).
They conducted a series of experiments on melting under simulated conditions of the lunar mantle, as well as partial crystallization of fragments of basalt rocks from samples that were mined by the Chang’e-5 drill.
Then they compared these data with similar experiments carried out with soil obtained by American astronauts.
It turned out that in the area where the Apollo crews worked, the basalts had, on average, 80 degrees higher melting point. And the rocks obtained by Chang’e-5 demonstrated comparative fusibility.
This difference is due to the higher concentration of calcium oxide and titanium dioxide in the basalts collected by the Chinese apparatus.
Late volcanism is thus explained by the presence of slightly more fusible rocks in the lunar mantle. About three billion years ago, the interior of the satellite cooled to temperatures close to the point of magma crystallization.
Consistently less refractory rocks solidified and came to the surface less and less frequently.
Apparently, the soil that Chang’e-5 collected is the last evidence of eruptions on the Moon, later even the most fusible magma cooled down and turned into basalt.
This hypothesis cannot yet be considered 100% proven; it requires additional data. But to date, this is the most logical and complete explanation for such late volcanism on the Moon.
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