A recent study published in Nature Astronomy has provided important insights into the clay terrains on Mars, which have intrigued scientists seeking signs of past life on the planet.
Researchers from The University of Texas at Austin and their collaborators have determined that many of these clay formations are linked to ancient bodies of standing water that existed on Mars billions of years ago.
This discovery emphasizes the role of these environments in the chemical weathering process that leads to the formation of thick, mineral-rich layers of clay.
According to Rhianna Moore, the study’s lead author and a former postdoctoral fellow at the UT Jackson School of Geosciences, the presence of stable terrains with abundant water conditions could have provided a favorable environment conducive to the development of life.
“These areas have a lot of water but not a lot of topographic uplift, so they’re very stable,” Moore explained.
The study was part of the Center for Planetary Systems Habitability at UT, which focuses on understanding the origins and requirements for life on Earth and extraterrestrial bodies.
Moore is currently engaged with NASA, supporting the Artemis mission to the Moon.
The researchers also highlighted that the thick clay deposits might indicate an imbalance in the water and carbon cycle on Mars, presenting a possible explanation for the scarcity of carbonate rocks in places where they should be abundant, based on Earth’s geological history.
Mars was once a wet planet, home to lakes and rivers that created distinct geological formations.
These clay layers formed in a wet period of Martian history, but their specific formation environments had largely remained elusive until this study.
Moore’s analysis was based on images and data from 150 clay deposits identified in a global survey conducted by NASA’s Mars Reconnaissance Orbiter.
She examined the topographical characteristics of these deposits and their proximity to other geological features, particularly former bodies of water.
The findings indicate that clay deposits are predominantly located at lower elevations near lake deposits, but notably away from valley networks, which are associated with robust water movement across the terrain.
The balance between chemical and physical weathering processes appears to have contributed to the enduring nature of these clay deposits over time.
Co-author Tim Goudge, an assistant professor at the Jackson School’s Department of Earth and Planetary Sciences, mirrored this sentiment, stating that the clay environments on Mars share characteristics with humid regions on Earth where thick clay mineral sequences typically form.
“On Earth, the places where we tend to see the thickest clay mineral sequences are in humid environments, and those with minimal physical erosion that can strip away newly created weathering products,” he noted.
However, the ancient Martian landscapes were quite different from the conditions observed on Earth today.
Unlike Earth, where active tectonic plates continuously expose fresh rock, Mars lacks such geological dynamics.
When CO2 was released into the Martian atmosphere from volcanic activity, the absence of newly reactive rock sources would have allowed this greenhouse gas to accumulate significantly.
This accumulation likely contributed to the planet becoming warmer and wetter, potentially enhancing the conditions necessary for clay formation.
The lack of new rock on the Martian surface likely impeded the chemical reactions that are necessary for the formation of carbonate rocks, which are expected to arise from volcanic rock under conditions involving CO2 and water over time.
Furthermore, the ongoing formation of clays could have played a role in the deficiency of carbonate rocks by absorbing water and trapping chemical byproducts in the clay, preventing them from leaching into the wider environment where they could engage in further geological reactions.
Moore surmised that this clay formation could be one of several factors contributing to the puzzling absence of predicted carbonates on Mars.
The research received funding from both NASA and the Canadian Institute for Advanced Research, highlighting the ongoing collaboration in planetary research and exploration.
image source from：https://www.jsg.utexas.edu/news/2025/06/thick-clay-layers-on-mars-may-have-been-stable-place-for-ancient-life/
