A groundbreaking study suggests that ancient Mars was far more dynamic and watery than previously thought.
Researchers from Rice University have found evidence that Mars’ thick crust in its southern highlands could have created rare granitic magmas and sustained vast underground water reservoirs billions of years ago.
This discovery challenges long-standing beliefs about the red planet’s geology and its potential for life.
Published in Earth and Planetary Science Letters, the study shows that Mars’ thick crust — up to 80 kilometers deep in some areas — was hot enough during its early history to partially melt in the lower layers.
This melting, caused by radioactive heating, likely produced granitic magmas similar to Earth’s. The heat also made it possible for underground aquifers of liquid water to exist beneath a frozen surface.
“Our findings reveal that Mars was more geologically active than we once believed,” said Cin-Ty Lee, professor of geology at Rice University.
“The thick crust in the southern highlands not only created granitic magmas without the need for plate tectonics but also sustained liquid water underground — a surprising discovery for a planet often thought to be cold and dry.”
The research team, which included Rice professors and scientists from the Lunar and Planetary Institute, used advanced computer models to study Mars’ crust during the Noachian and early Hesperian periods, about 3–4 billion years ago.
They analyzed how factors like crust thickness, heat from radioactive decay, and mantle heat flow affected the planet.
Their models revealed that areas with crust thicker than 50 kilometers likely experienced significant melting, forming felsic magmas like granite. These same regions also had enough heat to support stable groundwater aquifers several kilometers below the surface.
The study reshapes our understanding of Mars by showing that granitic rocks, which are common on Earth due to plate tectonics, could form on Mars through heat generated inside the planet.
These granites are likely hidden under layers of basalt in the southern highlands. Additionally, the researchers believe that ancient water reservoirs in these regions could have been periodically released by volcanic activity or asteroid impacts, causing temporary floods on the surface.
This discovery has exciting implications for Mars’ potential habitability. Granites often contain elements necessary for life, and the presence of liquid water increases the chances that ancient Mars may have supported life.
The study also provides clues for future exploration. Scientists suggest targeting craters and fractures in the southern highlands to search for granitic rocks and evidence of ancient water systems. “This brings us closer to answering key questions about Mars’ history and its ability to support life,” said Kirsten Siebach, a co-author of the study.
These findings shed new light on Mars’ complex history and its potential as a once-habitable world.
