Photo credit: www.sciencedaily.com
New Insights into Mars’ Geological History and Potential Habitability
Recent research has shed light on how changes in the thickness of Mars’ crust over its ancient history may have affected both its magmatic processes and water systems. The findings, detailed in Earth and Planetary Science Letters, indicate that the substantial crust of Mars’ southern highlands, which formed billions of years ago, may have contributed to the generation of granitic magmas and the existence of extensive underground aquifers. This challenges longstanding beliefs regarding the red planet’s geological and hydrological history.
The research, spearheaded by Cin-Ty Lee from Rice University, reveals that the crust in the southern highlands reaches thicknesses of up to 80 kilometers. During the Noachian and early Hesperian periods—dating back approximately 3-4 billion years—this thick crust was sufficiently hot to enable partial melting in its lower layers, a process fueled by radioactive heating. Such melting could have led to the formation of significant amounts of silicic magmas, like granites, and supported subsurface aquifers beneath a frozen exterior.
According to Lee, the Harry Carothers Wiess Professor of Geology, “Our research suggests that the crustal dynamics of Mars were far more complex than previously understood. The thick crust in the southern highlands not only potentially produced granitic magmas without the influence of plate tectonics but also established thermal environments conducive to stable groundwater aquifers, countering the view of Mars as merely a dry and frozen planet.”
The collaborative effort also featured contributions from Rice professors Rajdeep Dasgupta and Kirsten Siebach, postdoctoral associate Duncan Keller, and graduate students Jackson Borchardt and Julin Zhang, alongside Patrick McGovern from the Lunar and Planetary Institute. Utilizing advanced thermal modeling, the team was able to recreate the thermal conditions of Mars’ crust during the Noachian and early Hesperian epochs. Their simulations accounted for variables such as crustal thickness and both radioactive and mantle heat flow, aiding their understanding of how heat influenced crustal melting and groundwater stability.
Their results indicated that areas of crust thicker than 50 kilometers likely underwent significant partial melting, producing felsic magmas either through direct dehydration melting or as a result of fractional crystallization from intermediate magmas. Additionally, the elevated heat flow in the southern highlands meant that substantial groundwater aquifers were sustained deep beneath the crust.
These findings dispute the idea that granitic formations are exclusive to Earth, suggesting that Mars has the capacity to produce granitic magmas through radiogenic heating in the absence of plate tectonics. Such granites may still exist beneath layers of basalt in the southern highlands, providing fresh insights into the planet’s geological history. The study also underscores the possible existence of ancient groundwater systems in these regions, where high surface heat flux reduced the depth of permafrost and enabled the formation of stable subsurface aquifers. Volcanic activity or impacts could have periodically accessed these aquifers, leading to episodic surface flooding events.
The implications of this research are substantial for understanding Mars’ potential for habitability. The discovery of liquid water and the means to generate granitic magmas—which often contain elements essential for life—suggest that Mars’ southern highlands may have been more conducive to supporting life than previously assumed.
Dasgupta, who holds the Maurice Ewing Professorship in Earth, Environmental and Planetary Sciences, remarked, “Granites function not just as rocks, but as geological records detailing a planet’s thermal and chemical evolution. On Earth, granitic formations are linked with tectonic activity and water recycling. Evidence of similar magmas on Mars through deep crustal remelting highlights the planet’s complexity and its previous potential for life.”
The study also identifies specific locations on Mars that could be prime targets for future missions aimed at detecting granitic rocks or examining ancient water sources. For instance, large craters and fractures in the southern highlands might provide insights into the planet’s deep crustal structure.
“Each new understanding of Mars’ crustal mechanisms brings us closer to unraveling the profound questions of planetary science, particularly regarding Mars’ evolution and its potential to support life,” Siebach noted. “Our research lays down a blueprint for future exploration, guiding where and what to investigate in that search.”
This investigation received support from NASA under grant number 80NSSC18K0828.
Source
www.sciencedaily.com