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May 31 (UPI) -- Scientists have discovered several 'halos' of lighter-toned, silica-rich bedrock surrounding crustal fractures on the Red Planet. The geologic phenomena suggests Mars hosted liquid water for longer than previously thought. Scientists believe groundwater continued to flow on Mars even after surface water resources were long gone.
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Researchers measured the highest silica concentrations at the center of the halos, which suggests silicon oxide migrated from older, underlying sedimentary rock to newer, overlying rock -- the kind of chemical migration made possible by flowing water.
The chemical composition of bedrock found in Gale crater proved the depression was once filled with water, but scientists weren't sure how long the crater hosted an aqueous environment.
"What this finding tells us is that, even when the lake eventually evaporated, substantial amounts of groundwater were present for much longer than we previously thought -- thus further expanding the window for when life might have existed on Mars," Jens Frydenvang, a scientist at Los Alamos National Laboratory, said in a news release.
The latest findings -- detailed in the journal Geophysical Research Letters -- lend support to a recent study that posited the discovery of boron deposits as proof of Mars' watery history.
The halos were surveyed using the Curiosity rover's ChemCam instrument. Data collected by the ChemCam was analyzed by scientists with Los Alamos and France's space agency.
Researchers found the halos at high elevations among ancient lake sediment deposits rich in silica.
"This tells us that the silica found in halos in younger rocks close by was likely remobilized from the old sedimentary rocks by water flowing through the fractures," said Frydenvang.
Formation of the halos was likely influenced by wind -- dunes turned to rock -- further proof that the phenomena originated after Gale crater's lake had evaporated.
