A 'Giant Magma Network' Was Sleeping Beneath Mars: The Geological Wonder of a Planet Without Plates

It has long been common knowledge that Mars is a dead planet. It has no plate tectonics, surface volcanic activity ended long ago, and its interior has quietly cooled and solidified. In June 2026, a research team at the University of Oxford published a discovery in the journal 'Nature Astronomy' that fundamentally overturns this textbook image.

The possibility that a massive magma system, much like Earth's, once existed deep beneath the surface of Mars—few people would not be surprised to hear that.

InSight 'Pressed Its Ear' to the Ground

The key player in this discovery is NASA's Mars lander, 'InSight.' The most notable feature of this probe, which landed on Mars in 2018, was that it was a machine dedicated to 'listening' to the interior of Mars. It used high-precision sensors to record vibrations traveling through the ground whenever meteorite impacts or marsquakes occurred. It was a probe that kept its ear pressed to the ground, much like a doctor placing a stethoscope against a chest.

When this accumulated data was analyzed precisely using statistical models and thermodynamic calculations, it was revealed that there is an 'interface' about 24.5 kilometers below the surface where the properties of the rock change abruptly. While this itself was already known, its true nature had long remained a mystery.

The Truth Told by the 'Blood Type' of Rocks

Seismic waves are broadly divided into two types: P-waves (primary waves), which travel through both solids and liquids, and S-waves (secondary waves), which travel only through solids. Scientists discovered that Earth's core is liquid iron by using the property that S-waves disappear within liquid magma.

The research team used the same method to identify the rock types above and below the 24.5-kilometer boundary. The layer above the boundary consists of mafic rock (basaltic, with relatively high silicon content), while the layer below consists of ultramafic rock (rich in magnesium and iron). 'Mafic' is a portmanteau of magnesium and ferric, and it is a rock type commonly found in Earth's deep interior and volcanic regions.

This two-layer structure looks familiar. It is strikingly similar to the structure created beneath Earth's volcanic arcs as magma rises, cools, and solidifies, separating into lighter and heavier components—much like how a hot curry left to sit for a long time will see its ingredients sink, separating into a clear top layer and a denser bottom layer.

A Planet with a 'Stagnant Lid' Has the Same Mechanism as Earth

Mars is called a 'stagnant lid' planet. Unlike Earth, where the crust is divided into multiple moving plates, the entire surface is covered by a single, solid lid. Conventional wisdom held that without plate tectonics, complex differentiation of the crust was unlikely to occur.

However, this study suggests that transcrustal magmatism (magmatic activity penetrating the crust) occurred even without plates. By having mantle upwelling and igneous activity continuously supply heat, magma was able to repeatedly differentiate and evolve within the crust. This phenomenon was previously considered unique to Earth.

Even more surprising is that this layered structure may extend across a vast area of the northern hemisphere of Mars. Instead of isolated volcanoes scattered about, a giant magma network connected over hundreds of thousands of square kilometers may have spread underground.

'Earth is Special' Premise Collapses

The greatest significance of this discovery lies in re-examining the conditions for a planet's 'habitability.' Associate Professor Jon Wade of the University of Oxford states: 'One of the big questions in planetary science is whether Earth is special. If Mars could develop such a complex crust without plate tectonics, then habitable conditions might also exist on planets that have been dismissed due to the lack of plate tectonics.'

Plate tectonics is a mechanism that can be called the 'metabolism of a planet,' which stabilizes Earth's climate over the long term through the carbon and silicon cycles and continues to transport nutrients like phosphorus and sulfur from the oceans to the land. Mars lacks this. However, this discovery shows that complex geological evolution can occur through an entirely different route.

This discussion is also deeply related to the Mars life debate covered in our recent article, 'Life on Mars: Evidence of 'Biological Potential' Revealed by New Discoveries.'

The 'Cheyava Falls' rock, a candidate for life traces discovered by Perseverance, and the transcrustal magmatic activity identified this time fit together like pieces of a puzzle. The possibility that magma differentiated deep underground stirred up nutrients near the surface, creating an environment that microorganisms could utilize, is by no means absurd.

Future Mars Exploration Will Change

There is one more perspective from a practical standpoint that is worth noting. Lead author Dr. Mackay-Champion points out, 'There is a possibility that Mars contains more abundant underground mineral resources than expected.' This is because it is known that large-scale metal deposits such as copper, gold, and lithium are formed in regions on Earth where transcrustal magmatism occurs. From the perspective of future manned exploration and resource mining, this discovery can be said to raise the value of Mars by another notch.

The red world, once called a 'dead planet,' is being reborn as a planet that hides a rich history beneath its surface. Although the InSight lander has already completed its mission, the vibrations picked up by its 'ears' continue to tell new stories even now.

Reference Articles

〇Mars May Have Vast Magma Systems Beneath Its Surface (June 29, 2026)

〇Seismic evidence for a melt-depleted lower crust and transcrustal magmatism on Mars, Nature Astronomy (June 26, 2026)

〇Scientists find evidence of vast hidden magma systems inside Mars, EurekAlert! (June 26, 2026)

〇Enormous, Earth-like magma systems once existed inside Mars, The Brighter Side of News (June 27, 2026)

〇Life on Mars: New discoveries showing evidence of 'biological potential' (September 12, 2025)