Reading the Rocks: The Importance of the Margin Carbonate Unit on Mars

After greater than two and a half years of driving and exploring, Perseverance is closing in on an eagerly anticipated vacation spot: the margin carbonate unit.

The Mars 2020 scientists have been buzzing with pleasure this previous week as Perseverance makes its remaining method in the direction of a particular rock unit that performed a pivotal function in deciding on Jezero because the touchdown web site for exploration. Positioned in a slim band alongside the internal fringe of Jezero’s western crater rim, this layer showcases pronounced signatures of a mineral generally known as carbonate. On Earth, carbonates sometimes type within the shallow shoals of freshwater or alkaline lakes. It is hypothesized that this is perhaps the case for the margin carbonate unit on Mars too—over 3 billion years in the past, the waters of a lake in Jezero crater might need lapped in opposition to its shores, depositing this carbonate layer. Another speculation is that the carbonates shaped by mineral carbonation, the place silicate minerals (like olivine) react with CO₂ and are transformed to carbonates.

Carbonates are intriguing for a number of causes. Firstly, carbonates can supply insights into Mars’ bygone environment. These minerals type by a collection of chemical reactions that start when carbon dioxide (CO₂) from the environment reacts with liquid water. Thus, by learning the presence, abundance, and isotopic composition of those carbonates, our group could possibly infer Mars’ previous atmospheric CO₂ ranges and glean insights into its climatic historical past.

Second, carbonate minerals are a superb medium for preserving traces of historical life if it existed. When carbonates precipitate early within the rock-forming course of, they’ll seize a snapshot of the setting by which they shaped, together with any indicators of microbial life. On Earth, carbonate minerals have been noticed to type instantly round microbial cells, encapsulating them and quickly turning them to fossils. That is notably helpful as a result of as soon as an organism is encased in carbonate it may be preserved for a really very long time. One other instance of carbonate fossilization on Earth is stromatolites—layered buildings created by microbial colonies rising in mineral-saturated waters. Stromatolites symbolize a number of the earliest data of life on Earth. 

Though we don’t but know precisely how the margin rocks, or the carbonate inside them shaped, the group is raring to drill into these rocks and unlock their secrets and techniques. 


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