Will Mars’ Ancient Lakes & Seas Yield Fossils of Prior Life?

6a00d8341bf7f753ef0133f53a67e8970b.jpg J. Alexis Palmero Rodriguez, research scientist at Planetary Science Institue, has been studying the Martian northern lowlands region, which contains extensive sedimentary deposits that resemble the abyssal plains of Earth's ocean floors. It is also like the floors of other basins on Mars where oceans are thought to have developed.


One theory of the origin of the Martian lakes and seas is that there was a sudden release of large volumes of water and sediment from zones of apparent crustal collapse known as “chaotic terrains.” However, these zones of collapse are on the whole rare on Mars, while the plains deposits are widespread and common within large basin settings, Rodriguez said.

The image above shows a region of Mars that appears to be covered in salt crystals from ancient dried-up lakes, new evidence suggests. A Nasa probe has found signs that the southern hemisphere is dusted with chloride mineral, perhaps "table salt". NASA scientists think the mineral formed when water evaporated from salty lakes or soil billions of years ago.

Citing evidence found in the planet’s northern plains south of Gemini Scopuli in Planum Boreum, Rodriguez proposes that groundwater emerged through extensive and widespread fractures forming the floors of ancient continental-scale basins on Mars. This led to the formation of river systems, large-scale regional erosion, sedimentary deposition and water ponding.

This model does not require sudden massive groundwater discharges. Instead, it advocates for groundwater discharges being widespread, long-lived and common in the northern plains of Mars.“With the loss over time of water from the subsurface aquifer, areas of the northern plains ultimately collapsed, creating the rough hilly surfaces we see today. Some plateaus may have avoided this fate and preserved sedimentary plains containing an immense record of hydrologic activity,” Rodriguez said.

“The geologic record in the collapsed hilly regions would have been jumbled and largely lost. This model implies that groundwater discharges within basin settings on Mars may have been frequent and led to formation of mud pools, lakes and oceans. In addition, our model indicates this could have happened at any point in the planet’s history.

“There could have been many oceans on Mars over time.” If life existed in Martian underground systems, life forms could have been brought up to the surface via the discharges of these deep-seated fluids. Organisms and their fossils may therefore be preserved within some of these sedimentary strata, Rodriguez said.

Casey Kazan via Planetary Science Institute

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