Found underneath a lunar volcano that most likely erupted 3.5 billion years
ago are layers of cooled magma.
Another indication that the far side of the moon formerly sparkled with
volcanic eruptions is a huge granite deposit that was found under a
long-extinct lunar volcano.
On the surface of the moon, a formation known as Compton-Belkovich that is
thought to be volcanic was where the granite was discovered. This feature
probably developed as a result of the cooling of the magma that powered the
lunar volcanoes' explosive eruptions about 3.5 billion years ago.
This area of the moon has long been thought to be an old complex of
volcanoes, thus the discovery of volcanic activity remnants there is not
entirely surprising. But the size of this region of cooled magma, which has
an estimated diameter of about 31 miles (50 kilometers), has surprised the
crew. The finding of this substantial mass of granite under the
Compton-Belkovich volcanic complex may aid in the explanation of the origin
of the lunar crust.
Researchers from the Planetary Science Institute lead by Matthew Siegler
used information gathered by NASA's Lunar Reconnaissance Orbiter to make the
discovery of the granite body. The crew was able to measure the temperatures
beneath Compton-Belkovich's surface thanks to the orbiter's data. The
results revealed heat production that could only originate from radioactive
elements contained in granite, an igneous rock found in the "plumbing" of
volcanoes called "batholith," subterranean rock formations produced when
magma cools without erupting, which is only present on the moon.
The Cascade volcanoes in the Pacific Northwest are now being fed by a vast
system,
according
to Siegler. "Any big body of granite that we find on Earth used to feed a
big bunch of volcanoes," Siegler said in a statement. "Batholiths are
considerably larger than the surface-feeding volcanoes. For instance, the
Sierra Nevada mountains are a batholith that was left behind by a long-ago
volcanic sequence in the western United States.
On Earth, granite often forms as a result of water and plate tectonics
melting vast regions of rock known as melt bodies beneath the surface of our
planet. Granites are abundant on Earth but far more rare on the moon because
to the lack of plate tectonics and water. This means that this discovery may
shed light on the local or global circumstances that existed on the moon at
the time that it was the site of volcanic activity.
Granite can only be created under severe conditions if there is no water,
according to Siegler. "So, this system has granite despite lacking water and
plate tectonics. At least in this one location, did the moon formerly have
water? Or was it just very warm?
Between July 9 and July 14, Siegler will present the team's findings at the
Goldschmidt Conference in Lyon, France. The team's research is also covered
in a publication that appeared in the journal
Nature on July 5.
