Niles and his fellow researchers say that the basin now contains huge mineral deposits that were formed in a large sea of hot water, heated by volcanic activity. The volcanoes are no longer active and the sea has long since disappeared. These deposits represent the Red Planet's most ancient exposed crust.
They estimate the ancient Eridania Sea held about 50,000 cubic miles (210,000 cubic kilometers) of water, nearly 10 times more than the combined volume of the Great Lakes. The Eridania Sea would have been the largest body of water on Mars, containing as much as all other lakes and seas on Mars combined. Hot springs similar to hydrothermal vents called black smokers on Earth would have pumped mineral-laden water directly into the ancient Martian sea.
The minerals identified from CRISM’s orbital spectrometer include serpentine, talc, and carbonate, which are all evidence of water. Additionally, the shape and texture of the thick bedrock layers are consistent with seafloor hydrothermal deposits.
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Additionally, salts were observed only at higher elevations, likely representing a coastal shoreline where, so they feel there are several lines of evidence that strongly suggest Eridania was a sustained inland sea in the late-Noachian period.
"This site gives us a compelling story for a deep, long-lived sea and a deep-sea hydrothermal environment," Niles said. "It is evocative of the deep-sea hydrothermal environments on Earth, similar to environments where life might be found on other worlds — life that doesn't need a nice atmosphere or temperate surface, but just rocks, heat and water."