Using microwave frequency data, a team of scientists has uncovered the presence of a significant granite formation beneath the Moon’s surface. This discovery challenges existing theories about the formation of the lunar crust and suggests ancient volcanic activity on the Moon. The finding of granite, a rock type typically associated with water and plate tectonics, also raises intriguing questions about past lunar conditions.
The large granite formation that has been found beneath the Moon’s surface is believed to have originated from the cooling of molten lava that once fed a volcano or multiple volcanoes, erupting billions of years ago, as far back as 3.5 billion years.
Led by Matthew Siegler, a research professor at SMU and a scientist with the Planetary Science Institute, the team of scientists published their study in the journal Nature. They utilized microwave frequency data to measure the heat below the surface of a suspected volcanic feature on the Moon called Compton-Belkovich. The analysis of the data revealed that the heat source originates from a concentration of radioactive elements, a characteristic unique to granite found exclusively on the Moon.
Granites are remnants of igneous rock systems that lie beneath extinct volcanoes. When lava cools without erupting, it forms a granite formation known as a batholith. Siegler explains that large bodies of granite found on Earth are usually associated with feeding numerous volcanoes, analogous to the Cascade volcanoes in the Pacific Northwest today. Batholiths are significantly larger than the surface volcanoes they nourish. For example, the Sierra Nevada mountains in the western United States are a batholith resulting from a past volcanic chain.
The lunar batholith, located within a region previously identified as a volcanic complex, surprises researchers with its size, estimated to have a diameter of 50 kilometers.
While granite is relatively common on Earth, its formation is primarily driven by water and plate tectonics, processes absent on the Moon. Thus, the scarcity of granites on the Moon adds to the puzzle of how the lunar crust formed.
Siegler ponders whether the presence of this granite body suggests the existence of water in that specific lunar spot or if the extreme heat alone was responsible for its formation, given the Moon’s overall lack of water and absence of plate tectonics.
The research, titled “Remote detection of a lunar granitic batholith at Compton-Belkovich,” also involved contributions from other team members, including Jianqing Feng, Katelyn Lehman-Franco, Rita Economos, and Mackenzie White from SMU, Jeffrey Andrews-Hanna from the Southwest Research Institute, Michael St. Clair and Chase Million from Million Concepts, James Head III from Brown University, and Timothy Glotch from Stony Brook University.
Funding for the study was provided through NASA’s Lunar Data Analysis Program, as well as work related to the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer.
The team obtained data for their research from two Chinese lunar orbiters, Chang’E-1 and Chang’E-2, which were equipped with four-channel microwave radiometer instruments. The public data released by these orbiters is accessible for download from: http://moon.bao.ac.cn/index_en.jsp.
Siegler will present the team’s findings at the upcoming Goldschmidt Conference, scheduled to take place from July 9 to July 14 in Lyon, France.
Frequently Asked Questions (FAQs) about lunar granite
What did the scientists discover beneath the Moon’s surface?
The scientists discovered a massive granite formation beneath the Moon’s surface, indicating ancient volcanic activity and challenging existing theories about lunar crust formation.
What is the significance of finding granite on the Moon?
Finding granite on the Moon is significant because it is a rock type typically associated with water and plate tectonics, processes that are absent on the Moon. This raises questions about past lunar conditions and how the early lunar crust formed.
How did the scientists make this discovery?
The scientists used microwave frequency data obtained from lunar orbiter missions to measure the heat below the surface of a suspected volcanic feature called Compton-Belkovich. By analyzing the data, they were able to identify the presence of a concentration of radioactive elements, indicative of granite formation.
What is a batholith?
A batholith is a large formation of granite that forms when magma cools beneath the Earth’s surface without erupting. It is often associated with feeding volcanoes and can be significantly larger than the surface volcanoes it nourishes.
How does this discovery contribute to our understanding of the Moon?
This discovery challenges existing theories about lunar crust formation and provides insights into the history of volcanic activity on the Moon. It also raises questions about the presence of water or extreme heat in the specific lunar spot where the granite formation was found.
More about lunar granite
- Nature Journal: Remote detection of a lunar granitic batholith at Compton–Belkovich
- NASA’s Lunar Data Analysis Program
- Chang’E-1 and Chang’E-2 Lunar Orbiters
- Planetary Science Institute
- Southwest Research Institute
- Million Concepts
- Brown University Department of Earth, Environmental, and Planetary Sciences
- Stony Brook University Department of Geosciences
- Goldschmidt Conference
- SMU Research