MOON: ORIGIN, GEOLOGY AND RESOURCE POTENTIAL IN A UNIQUE PLANETARY BODY

Author: Silas Gonçalves, Geologist Engineer

ABSTRACT

The Moon is one of the most studied objects in the Solar System and exhibits unique geological characteristics when compared to Earth. Its origin, linked to a major planetary impact, led to a geological evolution marked by primitive volcanism, absence of active tectonics, and intense modification by impacts. This article addresses the Moon’s origin, its geological structure, differences between the near side and far side, and its mineral resource potential from an economic geology perspective.

1. ORIGIN OF THE MOON: CAPTURE OR LOCAL FORMATION?

Historically, three hypotheses were proposed for the origin of the Moon:

• Gravitational capture

• Co-formation with Earth

• Fission from the early Earth

However, the most widely accepted model today is the Giant Impact Hypothesis.

🌍 Giant Impact Model

According to this model, a Mars-sized body (commonly referred to as Theia) collided with the early Earth about 4.5 billion years ago.

👉 Consequences:

• Ejection of material from Earth's mantle

• Formation of a debris disk

• Subsequent accretion forming the Moon

📌 Key geological implication:The Moon has a composition similar to Earth’s mantle, particularly in silicate minerals.

2. GEOLOGICAL EVOLUTION

After its formation, the Moon underwent processes dominated by:

🔥 Magmatic differentiation

• Formation of a global magma ocean

• Crystallization of light minerals (anorthosite → crust)

🌋 Basaltic volcanism

• Infilling of large impact basins

• Formation of lunar “maria” (rich in Fe and Ti)

💥 Heavy bombardment

• Crater formation

• Exposure of deeper materials

3. MAIN GEOLOGICAL DOMAINS

🌑 Lunar maria

• Basalts rich in iron and titanium

• Age: ~3.0 to 3.8 billion years

⛰️ Highlands

• Anorthositic composition

• Oldest crustal units of the Moon

💥 Impact basins

• Giant structures

• Indirect access to mantle materials

4. THE FAR SIDE OF THE MOON

The so-called “far side” of the Moon is not permanently dark, but rather the hemisphere that is never visible from Earth due to synchronous rotation.

🌌 Main characteristics:

• Higher crater density

• Fewer basaltic maria

• Thicker crust

👉 Geological interpretation:

• Lower volcanic activity

• Reduced internal heat flow

• Limited magma ascent

📌 This indicates a significant thermal and structural asymmetry between the lunar hemispheres.

5. GEOCHEMISTRY AND COMPOSITION

The Moon exhibits geochemical characteristics distinct from Earth:

• Low volatile content

• Enrichment in:

  • Iron (Fe)

  • Titanium (Ti)

  • Aluminum (Al)

6. MINERAL RESOURCE POTENTIAL

From an economic geology perspective, the Moon hosts relevant resources, though with important limitations.

🟡 Helium-3 (He³)

• Implanted by the solar wind

• Potential fuel for nuclear fusion

6.1 Geological interpretation (technical level)

👉 Lunar He-3 is:

➡️ a dispersed, shallow, and non-concentrated resource

👉 fundamentally different from:

• Natural gas (reservoir systems)

• Petroleum (trapping systems)

6.2 Areas of higher concentration

More favorable regions:

🌑 Basaltic maria

• Richer in ilmenite (FeTiO₃)

• Higher He-3 retention

👉 Examples:

• Mare Tranquillitatis

• Oceanus Procellarum

🔢 Typical concentrations

• ~1 to 20 parts per billion (ppb)

🔵 Titanium (ilmenite)

• Abundant in basaltic units

• Industrial potential

⚫ Iron

• Widely present

• Potential use for in-situ construction

⚪ Aluminum

• Derived from anorthosites

• Structural applications

💧 Polar ice

• Essential for human support

• Potential fuel production (H₂ and O₂)

7. GEOLOGICAL LIMITATIONS

Unlike Earth, the Moon does not exhibit:

• Plate tectonics

• Hydrothermal circulation

• Secondary enrichment processes

👉 Result:

• Absence of concentrated ore deposits

• Resources distributed diffusely in the regolith

8. DISCUSSION

The Moon represents a primitive geological environment, preserving records from the early Solar System. Its mineral potential is significant but constrained by the absence of complex geological processes that, on Earth, lead to economically viable deposits.

9. CONCLUSION

The Moon was not captured by Earth, but formed from material ejected during a giant impact. Its geological evolution resulted in a body dominated by primitive magmatic processes and impacts, with diffusely distributed resources. While not currently a viable source of minerals for Earth, the Moon plays a strategic role as a platform for future space activities.