A recent study uncovers how variations in Mars’ crustal thickness billions of years ago shaped its magmatic evolution and underground water systems. Published in Earth and Planetary Science Letters, the research challenges long-standing ideas about Mars’ geological history and hints at a more dynamic and potentially habitable past.
Mars’ southern highlands: a hotbed of ancient activity
The thick crust of Mars’ southern highlands — reaching up to 80 kilometers in some areas — played a key role in generating granitic magmas and sustaining underground aquifers during the Noachian and early Hesperian periods (3–4 billion years ago).
“Our findings indicate that Mars’ crustal processes were far more dynamic than previously thought,” said Cin-Ty Lee, professor at Rice University. “Thick crust in the southern highlands not only generated granitic magmas without plate tectonics but also created the thermal conditions for stable groundwater aquifers — reservoirs of liquid water — on a planet we’ve often considered dry and frozen.”
Thermal modeling reveals crustal melting and aquifers
Using advanced thermal modeling, the research team simulated Mars’ crustal conditions during this early period. By analyzing factors like crustal thickness, radioactive heating, and mantle heat flow, they reconstructed how heat impacted crustal melting and groundwater stability.
The results showed:
- Crustal melting: Regions with crust over 50 kilometers thick experienced significant partial melting, producing felsic magmas such as granites.
- Groundwater systems: Elevated heat flow created stable subsurface aquifers several kilometers deep, even beneath a frozen surface.
These findings reveal that granites, often tied to plate tectonics on Earth, could form on Mars through radiogenic heating. Such magmas likely remain buried beneath basaltic flows in the southern highlands.
Implications for habitability and exploration
The study also sheds light on ancient groundwater reservoirs that could have been accessed by volcanic activity or impacts, triggering episodic surface flooding. These findings suggest that Mars’ southern highlands may have been more hospitable to life than previously thought.
“Granites aren’t just rocks; they’re geological archives that tell us about a planet’s thermal and chemical evolution,” said Rajdeep Dasgupta, professor at Rice University. “Evidence of granitic magmas on Mars underscores its geological complexity and potential for hosting life in the past.”
The research pinpoints areas in Mars’ southern highlands where future missions could search for granitic rocks or ancient water reservoirs. Large craters and fractures in these regions could offer valuable insights into Mars’ deep crust and hydrological history.
A roadmap for future Mars missions
“Every insight into Mars’ crustal processes brings us closer to answering profound questions about how Mars evolved and whether it could have supported life,” said Kirsten Siebach, a co-author of the study. “Our research provides a roadmap for where to look and what to search for in future explorations.”
This groundbreaking study reshapes our understanding of ancient Mars, highlighting its potential for life and offering exciting targets for future scientific missions.
Source: Rice University.
