Carbon Rocks Deep Underground Could Hold the Evidence of Mars' Watery Past.

A new geochemical study led by researchers from the Japan Aerospace Exploration Agency (JAXA) found that feldspar-rich rocks on Mars show possible evidence of interaction with water and carbonates, and that ground groundwater could be burying carbonates underground. The study, published in the journal JGR Planets, suggests that Mars may have had a wetter past, with groundwater interacting with rocks to form carbonates. The findings challenge the previous assumption that water interacted with the most common rock types on Mars.

The study involved doctoral student Chang-Chin Wang and Professor Tomohiro Usui of JAXA, along with Associate Professor Mohit Melwani Daswani from the Earth-Life Science Institute (ESLI). The research team used one-dimensional thermochemical models to simulate water's effect on minerals, tracking how water dissolved and created new minerals. The simulations showed that feldspar-rich rocks readily produce calcium/iron-rich carbonates under most conditions, while mafic rocks do so only briefly before the chemistry shifts toward magnesium-rich carbonates. This indicates that groundwater may have played a key role in forming these carbonates.

The study suggests that Mars may have had substantial stores of carbonate rocks beneath the surface, which parallels theories about Mars "missing water." The findings could help future Mars missions, such as drilling operations, to reveal evidence of Mars' warmer, wetter past and find underground water sources. The research also highlights the importance of groundwater in the formation of carbonates and the potential for future exploration of the planet's history.

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