Early Mars rocks reveal at least three separate water episodes
When NASA's Perseverance rover reached the inner edge of Mars' Jezero Crater in September 2023, mission scientists were surprised by what they found. The geologic area, called the "Margin Unit," stretches along the shoreline of an ancient Martian lake, so they expected sedimentary rocks, which would have formed as layers of sand piled on top of each other over millennia. Composed of clay and…
In September 2023, NASA's Perseverance rover arrived at Jezero Crater's inner edge, specifically the Margin Unit. This geologic area was expected to contain sedimentary rocks, evidence of past water activity, but instead, the team found igneous rocks formed by volcanic activity. Ignition rocks, rich in mineral crystals, offer a detailed record of the precise time they formed, preserving an intricate history of water activity on early Mars.
The Perseverance rover, equipped with the SuperCam instrument, analyzed over 185 bedrock targets in the Margin Unit. The findings published in the journal Communications Earth & Environment reveal that the rocks underwent water interactions at least three times.
Initially, carbon dioxide-rich groundwater reacted with olivine, resulting in carbonate-filled fractures at lower elevations. Later, lake-associated alteration increased silica levels beneath the waterline. Lastly, heated groundwater produced calcium sulfate and fluorite veins in eastern parts of the Margin Unit.
This series of water interactions transforms the geological narrative of Jezero Crater, emphasizing its significance in understanding Mars' climate and potential habitability.
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