Huge granite formations discovered under the surface of the moon

Microwave frequency data from the Lunar Orbiter reveal deposits of cooled magma beneath the volcano, which likely erupted 3.5 billion years ago.

Scientists have discovered a large formation of granite beneath the surface of the moon, indicating ancient volcanic activity and challenging existing theories about the formation of the lunar crust. The presence of granite, a rock type commonly associated with water and plate tectonics, raises questions about past conditions on the Moon.

A large formation of granite discovered beneath the moon’s surface likely formed from the cooling of molten lava feeding a volcano or volcanoes that erupted early in the moon’s history – 3.5 billion years ago.

A team of scientists led by Matthew Siegler, professor of research and research scientist at SMU in the Planetary Science Institute, has published a study in the journal nature which uses microwave frequency data to measure the heat beneath the surface of a suspected volcanic feature on the moon known as the Compton-Belkovitch. The team used the data to determine that the heat generated below the surface comes from a concentration of radioactive elements that can only be found on the moon, such as granite.

Granites are the igneous remnants of plumbing systems below extinct volcanoes. The granite formation left when lava cools without erupting is known as a batholith.

“Any large body of granite that we find on Earth used to feed a large group of volcanoes, much like a large system feeding the Cascade volcanoes in the Pacific Northwest today,” Siegler said. “Batholiths are much larger than surface-feeding volcanoes. For example, the Sierra Nevada Mountains are a basin of volcanic rock, left over from a volcanic chain in the western United States that has been around for a long time.”

The lunar bath basin is located in an area of ​​the moon previously identified as a volcanic complex, but the researchers were surprised by its size, estimated at 50 kilometers in diameter.

Granite is fairly common on Earth, and its formation is generally driven by water and plate tectonics, which aid in the formation of large melt bodies below the Earth’s surface. However, granite is extremely rare on the Moon, which lacks these processes.

Finding this granitic body helps explain how the early lunar crust formed.

“If you don’t have water, making granite requires tough situations,” Siegler said. “So this is a system with no water, no plate tectonics—but you have granite. Was there water on the Moon—at least in this one spot? Or was it particularly hot?”

Reference: “Remote Discovery of a Lunar Granite Basin at Compton-Belkovitch” By Matthew A. Siegler, Jianqing Feng, Caitlin Lyman-Franco, Jeffrey C. Andrews-Hanna, Rita C. Economos, Michael St. Clair, Chase Million, James W. Head, Available Here. Timothy D. Glutch and Mackenzie N. White, July 5, 2023, Available here. nature.
DOI: 10.1038/s41586-023-06183-5

Among the research team members was Jianqing Fang of the Institute of Planetary Sciences. Caitlin Lyman Franco, Rita Economos, and Mackenzie White of SMU; Jeffrey Andrews Hanna of the Southwest Research Institute; Michael St. Clair and Chase Million in a Million Concepts; James Head III of Brown University and Timothy Glotch of Stony Brook University.

The work was funded by[{” attribute=””>NASA’s Lunar Data Analysis Program and work related to the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer.

Data for the study was obtained from public data released from two Chinese lunar orbiters, Chang’E-1 in 2010 and Chang’E-2 in 2012, carrying four-channel microwave radiometer instruments. The original Chang’E‐1 and Chang’E-2 MRM data can be downloaded from: http://moon.bao.ac.cn/index_en.jsp.

Siegler will be presenting the team’s research at the upcoming Goldschmidt Conference, scheduled for July 9-14 in Lyon, France.