Mars, the enigmatic Red Planet, has long captured the imagination of scientists and explorers alike.
A recent study has provided groundbreaking insights into how variations in the planet’s crustal thickness billions of years ago may have influenced its geological and hydrological systems, reshaping our understanding of water on Mars.
The research, led by a team from Rice University, delves into the unique properties of Mars’ southern highlands.
These regions, with crustal thicknesses reaching up to 80 kilometres, appear to have been crucial in the planet’s magmatic and hydrological evolution.
During the Noachian and early Hesperian periods, between three to four billion years ago, the thick crust underwent partial melting due to intense heat generated by radioactive decay.
This process likely resulted in the formation of granitic magmas – silicic rocks traditionally associated with tectonic activity on Earth.
The findings suggest that the southern highlands were not just a frozen wasteland but a geologically active region, potentially hosting vast underground aquifers beneath a permafrost layer.
The role of heat in sustaining water on Mars
To unravel the ancient conditions of Mars, researchers employed advanced thermal models. These simulations accounted for factors such as the planet’s crustal thickness, heat flow from the mantle, and radioactive decay.
The results revealed that regions with thicker crusts experienced widespread partial melting, generating felsic magmas. More importantly, the elevated heat levels created stable groundwater reservoirs several kilometres below the surface.
These findings challenge the long-held belief that Mars is a dry and frozen planet. Instead, the presence of liquid water beneath the surface suggests a much more dynamic and habitable environment in its distant past.
Hidden granites and ancient aquifers
The study highlights the possibility that granitic rocks, typically hidden beneath basaltic flows in the southern highlands, could provide clues to Mars’ geologic history.
Unlike Earth, where plate tectonics drive the formation of granites, Mars achieved this feat through radiogenic heating. This process underscores the planet’s capacity for complex geological processes despite the absence of tectonic activity.
In addition to magmatic evolution, the research sheds light on ancient systems of water on Mars that may have existed within the southern highlands.
Elevated surface heat likely minimised the extent of permafrost, creating conditions for stable underground aquifers. These reservoirs could have been periodically accessed by volcanic activity or meteorite impacts, triggering episodic flooding events and shaping Mars’ surface features.
Implications for habitability and future exploration
The discovery of granitic magmas and subsurface aquifers has significant implications for Mars’ habitability.
Granite is often rich in elements essential for life, and the presence of liquid water on Mars adds another layer of potential for ancient microbial life. Mars’ southern highlands, in particular, emerge as a promising area for future exploration.
The study suggests that large craters and fractures in the highlands could provide direct access to the planet’s deep crust, offering a window into its geological and hydrological history.
By targeting these regions, upcoming missions could uncover evidence of granitic rocks and ancient water reservoirs, shedding light on the conditions that might have supported life.
Professor Rajdeep Dasgupta explained: “Granites aren’t just rocks; they’re geological archives that tell us about a planet’s thermal and chemical evolution.
“On Earth, granites are tied to tectonics and water recycling. The fact that we see evidence for similar magmas on Mars through deep crustal remelting underscores the planet’s complexity and its potential for hosting life in the past.”
A new chapter in Mars exploration
The research reframes our understanding of water on Mars, suggesting that the Red Planet’s crustal processes were far more dynamic than previously assumed.
The interplay between thick crust, radiogenic heating, and hydrological systems paints a picture of a planet that was once more Earth-like in its capacity to host life.
As exploration of Mars continues, these findings provide a roadmap for discovering its hidden geological and hydrological secrets.
